Contextualizing Chemistry in Art and Archaeology: Inspiration for Instructors 0841298335, 9780841298330
Chemistry serves a critical role in the fields of archaeology and art, from assisting in the reconstruction of humanity&
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English Pages 486 [488] Year 2022
Foreword
Contents
Preface–Chemistry’s Diverse Applications in Art and Archaeology
Chemistry’s Role in Art and Archaeology
Teaching Chemistry in Context
Bringing Art and Archaeology into the Chemistry Classroom
Acknowledgement of Inspiration
Chapter Organization
Conclusion
Acknowledgments
References
General Chemistry
1. Incorporating Conservation Science into the General Education Curriculum • Joan M. Esson
Introduction
Conservation Science in Sabbatical Studies
Scheme 1. Graphic Illustrating Four Main Roles of a Conservation Scientist (Left), the Experiences Gained Before or During My Sabbatical (Middle), and the Projects Introduced into the Curriculum (Right)
Role 1: Conducting Research to Aid in Art Historical Analysis
Role 2: Curating Exhibits
Role 3: Fundamental Scientific Research
Role 4: Supporting Conservators
Incorporating Conservation Science Principles into a General Education Chemistry in Art Course
Curating an Exhibit (Role 2)
Supporting Conservators (Role 4)
Conducting Art Historical Analysis – Search for Authenticity (Role 1)
Figure 1. Example of illuminated manuscript page studied (left). Area A is the tiger from which Raman spectrum A was taken (A). Area B is green grass from which Raman spectrum B was taken (B). Raman spectrum A is similar to that expected for chrome yellow. Further, the similarity of Raman spectra A and B suggests that the green color was made from chrome yellow and an unidentified blue colorant.
Fundamental Research of Materials in Art and Cultural Heritage (Role 3)
Project 1: Anthotype Plant Prints
Project 2: Dyeing Studies
Scheme 2. Acid-Base Behavior of Phenoxazines
Figure 2. Fabric test strip as it is removed from the muitle dyebath (left). Fabric test strips under ambient light (middle) and 254 nm UV light (right) dyed with Justicia spicigera (top row) or Peristrophe bivalvis (bottom row). The top test strips from left to right are dyed with the following mordant-pH combinations: alum-acid, alum-base, iron-acid, iron-base. The bottom test strips are dyed with alum-acid and alum-base. The identity of the fibers in each test strip from top to bottom are filament acetate, cotton, nylon, polyester, polyacrylic, silk, viscose, and wool.
Figure 3. Color parameters of the wool fibers from Figure 2 projected on the a*b* plane of the CIE L*a*b*color space. Note that fibers dyed under acidic conditions have greater a values (are more red) compared to those dyed under basic conditions. Also, b and a values for fibers mordanted with alum differ between P. bivalvis and J. spicigera, which suggests different phenoxazine molecules are present in each.
Engagement, Extension and Conclusions
Acknowledgments
References
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2. Archaeological and Historical Pigments: A Unifying Framework for Delivering Relevant Chemical Content Utilizing an Interdisciplinary Approach • Christopher R. Vyhnal and Roxanne Radpour
Introduction
Radiometric Age Dating of Cave and Rock Art
Pigment Synthesis Experiments
Madder Lake Synthesis
Prussian Blue Synthesis
Cobalt Green Synthesis
Figure 1. A plot of the percentage of initial reactant mass loss due to evolution of volatile gases versus the percent yield of cobalt green pigment. The red diamond represents the theoretical values expected for a trial using 1.00 g of cobalt(II) chloride hexahydrate with 5.00 g of zinc oxide. Open blue squares represent teacher-conducted experiments completed during the design of the course; filled green circles represent the results of student laboratory groups from two different iterations of the synthesis experiment. Excess mass loss and low percent yields (upper left) are attributed to spillage during heating, stirring, and weighing. A low percent mass loss and a high percent yield (lower right) is attributed to an incomplete reaction.
UV-Vis-NIR Fiber Optic Spectroscopy Measurements
Figure 2. Experimental set-up for fiber optic spectroscopy measurements of pigment powders and gouache watercolor paints. Methods generally follow Vyhnal et al. (2020) 28; absorption spectra were collected using Vernier software with an Ocean Optics spectrophotometer equipped with a fiber optic cable. Operating conditions were maintained at 50 ms integration time, sampling every 2 nm from 388−950 nm wavelength and averaging 30 samples per spectrum. Data were first reduced in our own spreadsheets by 1) converting absorbance values to reflectance values, 2) conducting a “dark” subtraction using a spectra obtained with the cap in place over the end of the fiber optic cable, 3) performing a white normalization to BaSO4, and 4) smoothing to a five-point average reflectance measurement centered on each wavelength. In order to obtain CIE L*a*b* coordinates and RGB values for color quantification and digital color reconstruction the spectra were then 5) condensed to a 5 nm sampling interval between 390 and 830 nm, and 6) copied into a spectral calculator spreadsheet 29 (the 2-degree A illuminant was used). Photo by C.R. Vyhnal.
Figure 3. Examples of diffuse reflectance spectra obtained from dry pigment powders synthesized in our own experiments during course development. The colors of the spectra reflect their actual RGB color coordinates converted from CIE L*a*b* colorimetric values. Along the right margin of the graph from top to bottom the spectra are: madder lake, Han blue, cobalt yellow, cobalt green, Egyptian blue, Prussian blue. Adapted with permission from reference 30. Copyright 2020 Journal of Chemical Education.
Figure 4. Plot of CIE colorimetric coordinates b* vs a* for the powdered pigments listed in Table 3. a* indicates color from greens (at negative values) to reds (at positive values). b* indicates color from blues (at negative values) to yellows (at positive values). The colors of the points reflect their actual RGB color coordinates converted from CIE L*a*b* colorimetric values. Clockwise from top the clusters are: cobalt yellow, madder lake, Prussian blue, Egyptian and Han blues, cobalt green. Closed circles: Thacher analyses; open circles: CHSOS Pigments Checker v3.0 32 FORS data, provided for comparison. Adapted with permission from reference 33. Copyright 2020 Journal of Chemical Education.
Figure 5. Screen captures of Vernier’s Logger Pro 40 software that show how reflectance spectra can be analyzed to identify a local minimum in reflectance (for example, an absorption peak) for comparison with those identified in other studies. a) Using the Analyze/Statistics option on a highlighted data range to find the wavelength of the reflectance minimum. b) Fitting lines to the limbs on either side of a local minimum in the first derivative of reflectance and then using the Analyze/Examine option to find the intersection of the lines and the wavelength of the reflectance minimum.
Painting a Fresco Tile: Chemical Reactions in the Fresco Lime Cycle
Figure 6. a) Tracing paper cartoon for pouncing (“spolvero”) transfer of vine black to the wet plaster as part of the fresco technique. b) Finished fresco tile that incorporates provided pigments (red earth, Han blue) and those pigments the student synthesized from the laboratory modules (cobalt yellow, cobalt green). In the top left corner are visible the ceramic tile itself (representing the wall or “muro”), the rough plaster layer (“arriccio”), and the fine plaster layer (“intonaco”) on which the hummingbird is painted. Artwork by Avery Budlong is reproduced here with her permission. Photos by C.R. Vyhnal.
Using the Cultural Heritage Science Open Source (CHSOS) Spectral Databases as a Resource for Pigment Identification and an Instructional Tool for Analytical Chemistry
Concluding Thoughts
Acknowledgments
References
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3. Connecting Chemistry and Cultural Heritage: Presenting the Physical Sciences to Non-science Majors and First-Year Students through the Investigation of Works of Art and Archaeological Artifacts • Citlalli Rojas Huerta and Maria Parr
Introduction
Archaeological Chemistry: A Lecture Course Designed for Non-science Majors
Course Design, Materials and Topics
Figure 1. Elemental analysis of obsidian showing peaks for iron, rubidium, zirconium and zinc obtained with a Tracer III-V portable X-ray fluorescence analyzer on loan from Bruker Handheld LLC. Courtesy of Dr. Bruce Kaiser.
Figure 2. Potsherd analyzed by SEM-EDS (left) and SEM micrograph of cross-section (right): a = matrix; b = inclusion; c= pigment; potsherd dimensions: 7.3 cm (l) x 7.5 cm (h) x 0.4 cm (w).
Figure 3. EDS data of the aluminosilicate matrix, a, (upper); the inclusion, b, (middle); and the pigment, c, (lower) of potsherd shown in Figure 2. Horizontal axis: energy in keV; vertical axis: intensity in counts.
Laboratory Workshops
Assessment and Student Feedback
Bones, Pigments and Native Metals: A Scientist’s Guide to Art and Archaeology: A Seminar Course Designed for First-Year Students
Course Design, Materials and Topics
Figure 4. Urbs Roma coin - obverse (left) and reverse (right); scale: 1 division = 1 mm.
Figure 5. EDS spectrum of helmet area (Figure 4, left) showing the presence of copper, tin and lead, an alloy composition typical of bronze.
Laboratory Workshops
Assessment and Student Feedback
Conclusion
Acknowledgments
References
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4. Using Examples from Art and Archaeology to Demonstrate the Chemistry of Materials in a General Education Course • Jennifer E. Mihalick
Introduction
Chemistry of Materials Course Design
Figure 1. Homework assignment for the chapter on pottery.
Addressing Course Objectives using Art and Archaeology
Development of Metals and Alloys
Figure 2. Assessment questions for metals and alloys.
Development of Polymers, Dyes, and Paints
Figure 3. Assessment questions for polymers, dyes, and paints.
Development of Ceramics
Figure 4. Assessment questions for ceramics.
Art-Related Activities
Analysis of Art Objects
Figure 5. Ceramics tested for metals: (a) dog; (b) tiger.
Demonstrations of Intermolecular Forces with Artists’ Materials
Figure 6. Results of experiments with intermolecular forces: (a) various fibers dyed marigold or tea extracts and metal mordants; (b) food dyes separated on paper.
Syntheses of Artists’ Materials
Figure 7. Products of synthetic labs: (a) polyester resin and filaments; (b) painting with Prussian Blue; (c) colored silica glass.
Limits of the Laboratory Experience
Artists Show and Tell
Conclusions
Acknowledgments
References
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5. Using the History of Technology to Connect Art and Chemistry in a Science of Art Course for Nonscience Majors • Brian McBurnett
Course Structure and Content
Section 1: Light, Measurement, and Color
Section 2: Atoms, Reactions, and Stoichiometry
Section 3: Bonding, Intermolecular Forces, and Polymers
Chemical Concepts Inventory
Discussion and Conclusions
Acknowledgments
References
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6. Making Light Work: A First-Year Writing Course on Art, Colors, and Chemistry • Benjamin J.McFarland
Introduction
Lecture: Twelve Questions and a Writing Project
A “What is a Flame?”
B “How Does Science Work?”
C “How Did Science Find a Hidden Van Gogh Portrait?”
D “How Does Color Work?”
E “How Were Natural Colors Found?”
F “How Were the First Synthetic Colors Made?”
G “How Were New Colors Made in Medieval Times?”
H “How Did Scientists Synthesize New Colors?”
I “Why Do Colors Fade and Make People Sick?”
J “How Do You Put Colors Together?”
K “Is This Painting a Forgery?”
L “How Do I Analyze the Colors in Art Myself?”
Final Writing Project
Lab: Making Pigments and Making Art
Figure 1. Pigments synthesized by a student during two weeks of lab instruction. From left to right: verdigris, zinc-based chrome yellow, madder lake, and Prussian blue.
Figure 2. A palette containing paints composed of the student-synthesized pigments combined with different binders, including egg tempera, gum arabic, and acrylic binders.
Student Feedback
Conclusions
Acknowledgments
References
Instrumentation
7. The Chemistry of Art and Artifacts: A Sophomore-Level, Thematic Chemical Instrumentation Course • Kristin Jansen Labby
Introduction
The Interdisciplinary Nature of the Course
Figure 1. Illustration of the three-legged stool of conservation. Conservators work and collaborate at the intersection of three broadly defined disciplines: history, science, and the fine arts.
Details of Course Structure and Delivery
Course Learning Goals
Course Content
Introductory Activity: Art Conservation and IMFs
Figure 2. In the introductory activity, “Restoring Rothko,” students make paint of casein, gum Arabic, and linseed oil binders (a), and apply those paints to canvas and mimic the vandalism event by applying graffiti ink over a portion of each type of paint (b).
Gas Chromatography Unit
Introduction to Chromatography
Figure 3. Silica gel column chromatography to separate a purple mixture of food dyes. (a) Using a glass pipette keeps the scale of the column small and manageable. (b) Due to polarity differences, the blue, red, and pink food dye components separate nicely.
Investigation of the Experimental Parameters of Gas Chromatography
GC Analysis of Lipid Residue from Archeological Pottery
Figure 4. Scheme of procedure for pottery sherd lipid residue derivatization and GC analysis.
Ethnobotany Activity
Color and Light
Examination of Paintings by XRF to Infer Pigment Composition
Pigment Timelines
X-ray Fluorescence Spectroscopy
XRF of Paintings Activity
Figure 5. This is an example of a student figure of XRF data from pigment analysis of Adoration of the Magi, School of Lucas Cranach ca. 1513. Courtesy of Wright Museum of Art Collection, Beloit College.
Pigment Synthesis and Analysis by XRD
Additional Activities and Possible Course Expansions
Technical Photography of Paintings
Cultural Heritage Preservation Literature Presentations
Student Feedback and Conclusions
Figure 6. Distribution of student responses to end of course survey questions from CHEM 225 Spring 2019 (n=5) and Spring 2020 (n=5).
Acknowledgments
References
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8. X-ray Fluorescence Spectroscopy in Painting Analyses: Undergraduate Classroom, Teaching Laboratory, and Research • Erich S.Uffelman, Liesbeth Abraham, Andrea Abry, Nicholas Barbi, Harris Billings, Sydney Collins, Sam Florescu, Christina Kargol, Jorinde Koenen, Mireille te Marvelde, Jennifer L. Mass, Leo Mazow, Daniel Monteagudo, Kathryn Muensterman, Carol W. Sawyer, Kate Seymour, and Mallory Stephenson
Introduction
A General Chemistry pXRF Laboratory
Figure 1. Maerten van Heemskerck (1498-1574) The Prophet Isaiah Predicting the Return of the Jews from Exile (oil on panel, ca. 1560, H40.0 cm x W49.0 cm), Frans Hals Museum. (Obtained from Elisabeth van Thüringenfonds, 2011) Original image courtesy of the Frans Hals Museum; Photo: René Gerritsen.
Figure 2. Spectral subset of the 0-40 keV pXRF spectrum of “Spot 1”—the buff colored mantle of Isaiah. The broad curves are the actual data; the vertical lines represent theoretical spectral transition energies and intensities. If we consider the spectral region between 10-15 keV here, mercury (coded in blue), lead (coded in red), and arsenic (coded in green) present overlap problems. In this case, the interpretation, although tricky for novice students, is clear: The Hg Lα1 peak (9.99 keV) is the dominant line for Hg, so the Hg Lβ1 and Lβ2 peaks 11.82 and 11.91 keV, respectively) cannot contribute enough intensity to account for the magnitude of the peak at 11.73 keV, which must therefore be an As Kβ1 signal. Note that observing the As Kβ1 signal is crucial, because the Pb Lα1 peak (10.55 keV) interferes so strongly with assigning the As Kα1 signal (10.54 keV).
Figure 3. “Spot 14” Gray sky in upper right. Novice students working together in the lab with online pigment data bases get, understandably, confused by this spectrum. The sky in the painting does not look blue, but they see an obvious cobalt peak, which a superficial scan of the web will make them think of cobalt blue and smalt. Cobalt blue is not historically germane (developed well after Heemskerck’s lifetime), so smalt seems like a choice, but then why does the painting not look blue? And if arsenic is present (and the small As Kβ1 signal at 11.73 keV says it is), is there some orpiment or realgar present? This leads the class into a brief discussion of smalt degradation and the contamination of cobalt ores with arsenic.
General XRF Interpretation Pedagogical Comments
MA-XRF Imaging
Comments on Context, Learning Objectives, and Assessment
General Considerations
MA-XRF Imaging of a VMFA Henri Painting
Figure 4. Robert Henri (American, 1865-1929) The Towhead, 1907; Oil on canvas; 24⅛”H × 20⅛”W, 61.28 cm × 51.12 cm; signed lower left, Robert Henri. Virginia Museum of Fine Arts, Richmond; Arthur and Margaret Glasgow Endowment, 2018.340. Photo: Travis Fullerton; Copyright Virginia Museum of Fine Arts
Figure 5. Left: As Sawyer and Kargol prepare The Towhead for imaging, the studio light at an oblique angle (green arrow) shows the overpainted area in relief (blue arrow). The tacking margin (magenta arrow), usually covered by the frame, shows prior areas of the dress that were not overpainted. Right: The X-ray head of the CRONO, prior to scanning the painting. [Both photos taken by Erich Uffelman, the Towhead painting courtesy of the Virginia Museum of Fine Arts.]
Figure 6. Left: Iron map (likely indicating various ochres) of a portion of The Towhead. Right: Mercury map (indicative of vermilion) of the same portion of The Towhead. Original art courtesy of the Virginia Museum of Fine Arts.
Figure 7. Zinc map (indicative of zinc white) of the same portion of The Towhead as seen in Figure 6. Original art courtesy of the Virginia Museum of Fine Arts.
Pandemic Remote Course on the Imaging of Old Master Paintings
Motivation
Comments on Context, Learning Objectives, Assessment
Course Content and Structure
Closing Thoughts and the Future
Conclusion
Experimental
A Note on the Figures
Supplementary Material
Acknowledgments
References
9
9. Multispectral and Hyperspectral Reflectance Imaging Spectrometry (VIS, VNIR, SWIR) in Painting Analyses: Undergraduate Teaching and Interfacial Undergraduate Research at the Nexus of Chemistry and Art • Erich S. Uffelman, Liesbeth Abraham, John P. Davis, John K. Delaney, Kathryn A. Dooley, Lindsey Hewitt, Jorinde Koenen, Mireille te Marvelde, Kathryn Muensterman, Konstantinos Oikonomou, Darcy Olmstead, Trinity Perdue, Jensen Rocha, Jessica Roeders, Annika Roy, and Lidwien Speleers
Introduction
Brief Overview of Courses and Context
Old Master Paintings
Figure 1. An old master painting (upper left) was typically constructed from several layers, beginning with the support and concluding with the varnish.
Figure 2. A data cube of a detail of a painting by Jacob and Aelbert Cuyp (vide infra) prepared using the ENVI (Harris Geospatial) Build 3D Cube procedure. This cube was obtained with 260 spectral bands from 384-1041 nm, but has been spectrally cropped to 396-1004 nm to eliminate excessively noisy data.The image at the front of the cube is actually a false color map produced from three spectral bands fed into the RGB channels of the cube builder. The painting images at each wavelength are parallel to the xy-plane of the cube, and the z-axis of the cube is the wavelength axis. Original art courtesy of the Dordrechts Museum.
The Image Data Cube
Figure 3. Building a cube from point measurements (the “raw spaghetti” method). Although this technique was not used to acquire any data in this chapter, this method of building a data cube rasters a point measuring instrument (such as a fiber optic reflectance spectrometer, or an X-ray fluorescence instrument) back and forth above the surface of the painting. Although the first four measurements are conceptually illustrated here (upper left), real systems will measure from thousands to millions of points. Each point consists of a full spectrum, and packing the “raw spaghetti” together generates the data cube. The spatial resolution will be determined by the spatial resolution of the point measurement instrument and the spatial sampling frequency; the spectral resolution will depend on the spectral resolution of the instrument being rastered. Original art courtesy of the Dordrechts Museum.
Figure 4. Building a data cube from filter images. This cube is a detail of a painting by Maerten van Heemskerck (vide infra) prepared using the ENVI (Harris Geospatial) Build 3D Cube procedure. This cube was obtained with five filters spanning 900-1700 nm. Each filter image is an average (roughly speaking) of the photon intensities for that filter’s wavelength bandpass range, and each image is 640 x 512 pixels. The image at the front of the cube is actually a “false color” map produced from feeding the images from filters 1, 3, and 5 into the RGB channels of the cube builder and then converting the false color image to grayscale. Original art courtesy of the Frans Hals Museum.
Figure 5. Top: Schematic of a push broom hyperspectral camera. Light reflected from the painting enters the lens, is focused on the slit, enters the diffraction grating, and is projected onto the sensor. Each image the sensor records is a thin y-axis slit image of the painting spread out as a spectrum on the sensor. Bottom: Same cube as Figure 2. The y-axis of the sensor is the slit image of the painting and the x-axis of the sensor becomes the spectral λ-axis. Each yz-slice of the cube results from projecting the slit image onto the xy-plane of the camera sensor. The slit is moved internally across the painting image so that the cube is composed of yz-slices (y-axis painting slit image; z-axis spectral dimension) composited along the x-axis (also a painting image axis). This figure shows roughly 20 slices for clarity, but in fact, this cube is composed of 696 slices, each 696 pixels tall; the final cube measures 696 x 696 pixels in the xy-painting-image-plane and 241 wavelengths deep along the z-axis. The right-most slice is depicted on the sensor in the Top figure. Original art courtesy of the Dordrechts Museum.
Resolution
Spatial Resolution
Depth Resolution
Spectral Resolution
Intensity Resolution
Obtaining the Image Data Cube
Figure 6. Top left: A white reference image for a filter with 90 nm bandwidth, centered at 1675 nm. This type of image occurs for all filters in a multispectral image and in the various wavelength bands in the white cube for a hyperspectral imaging system (i.e., there are intensity gradients across the field of view). Top right: A dark reference image for the same filter that has been severely cropped, blown up, and had its exposure drastically increased to show the noise from the dark current. Bottom: An image of a Heemskerck painting (vide infra) through the same filter. For the purposes of printing in this chapter, the exposure has been boosted, compared to the raw input actually used in the flat-fielding procedure. Note the 2% reflectance standard and the 99% reflectance standard at the left of the image, and note the shadows they cast in the image. Both the standards and the shadows must be spatially cropped from the final cube before running PCA. Original art courtesy of the Frans Hals Museum.
Figure 7. Erich Uffelman (1962- ) Paint Samples (2020, unsigned), 10 cm x 15 cm, detail. Some pigments in linseed oil applied to gessoed linen canvas for illustration purposes; graphite text. Top row: titanium white, zinc white, vermilion, cadmium red, ultramarine. Second row: Prussian blue, cadmium yellow, Indian yellow, yellow ochre, brown umber. Third row: ivory black, permanent green light, phthalo green, manganese violet, cerulean blue. Fourth row—all mixed with titanium white: ultramarine, Prussian blue, cerulean blue, brown umber, vermilion. Fifth row—all mixed with titanium white: ivory black, ultramarine mixed with vermilion, phthalo green.
Figure 8. Top left: A hyperspectral cube of Paint Samples was acquired from 380-1020 nm in 260 spectral bands. This reflectance spectrum is a z-profile of a pixel of the raw data cube from the ultramarine region of the painting. Compared to the processed cubes (vide infra), this spectrum shows the profound effect of black body radiator illumination effects coupled with differing sensor sensitivity across the measured spectrum. Top right: This spectrum is a z-profile of the same pixel from the flat-fielded data cube from the ultramarine region of the painting. The extraordinary impact of flat-fielding on the spectral appearance is apparent. Bottom left: This spectrum is a z-profile of the same pixel from the calibrated and flat-fielded data cube from the ultramarine region of the painting. The impact of calibration now becomes apparent.
A Mathematical Interlude
Creating the Calibrated Image Data Cube
Flat-Fielding
Image Registration
Calibration
Running PCA on the Calibrated Image Data Cube
Principal Component Analysis (PCA) and Minimum Noise Fraction (MNF)
Figure 9. Top: The formula for covariance. If x and y are the same variable, then it is the formula for variance. Next: A five variable data set (e.g., five wavelength bands) will provide a 5x5 square, symmetric covariance matrix. Next: A Square, symmetric matrix (A) must have a number of eigenvectors (x) and eigenvalues (λ) equal to the number of rows or columns. Bottom: The eigenvector is a column matrix, and when it is multiplied by the square, symmetric covariance matrix, it gives the eigenvector back, multiplied by a scalar eigenvalue.
Figure 10. The calibrated, flat-fielded cube has had its spectral region narrowed to 396-1004 nm (241 bands) by taking a spectral subset of the 260 band data, and a forward MNF transform has been applied. Top left: This is MNF band 1 of 246. Top right: This is MNF band 10 of 246. The increasing noise is readily apparent. Note that if one had used a ten filter multispectral system, the data set would be underdetermined; i.e., in MNF band 10, we still see clear spatial signal. Bottom left: This is MNF band 25 of 246. The remaining 221 bands look very similar to this. Clearly, the data set is overdetermined, because noise is the overwhelming feature in this image. We know that we may safely discard information from this data set that is essentially redundant.
Figure 11. A plot of eigenvalue vs eigenvalue number (functionally equivalent to MNF band number) for the 241 band subset of the hyperspectral cube in Figure 10. Given that Paint Samples has fifteen pigments and eight combinations of those pigments and graphite text and a gessoed canvas, it is not surprising that the asymptotic approach to noise in this plot has become essentially complete by eigenvalue number 25. This is another way of showing that the data set is overdetermined, and that redundant information may be safely discarded. The ENVI Spectral Hourglass Wizard calculates 66 bands above its eigenvalue threshold, but this is an extremely conservative value.
Underdetermined versus Overdetermined Data
Pixel Puritiy Index (PPI)
Spectral Angle Mapper (SAM)
Mixture Tuned Matched Filtering (MTMF)
Optimizing Results
Figure 12. Here, we see the practical application of the plot of eigenvalue vs eigenvalue number shown in Figure 11. In Figure 11, we saw the asymptotic approach to noise being essentially complete by eigenvalue number 25. Top left: This is the ultramarine reflectance spectrum (400-1000 nm) from a pixel in Paint Samples after the calibrated data set has had a forward MNF transform followed by an inverse MNF transform using the 35 highest eigenvalue bands; the effects of denoising are subtle. In other words we have retained more noise than we would like. Top right: The same pixel after the data set has had forward/inverse MNF transforms using the 25 highest eigenvalue bands; the effects of denoising are much more pronounced, but the spectral shape has retained its integrity. Bottom left: The same pixel after the data set has had forward/inverse MNF transforms using the 10 highest eigenvalue bands. This is an action that should not be taken. Bands have been rejected that contain relevant information, and the spectrum has been deformed as a consequence. Bottom right: The same pixel after the data set has had forward/inverse MNF transforms using the 5 highest eigenvalue bands. This highly distorted spectrum emphasizes that it is crucial not to exclude bands that contain relevant information from an inverse MNF transform.
Figure 13. A 212 pixel-containing ellipse was selected within the ultramarine area of Paint Samples and ROI (region of interest) statistics were chosen. The red lines represent the most extreme values of reflectance measured. The green lines represent one standard deviation about the mean (the white curve). This represents another way of increasing the signal to noise ratio in a measurement from the cube, but it requires having several contiguous pixels that may be assumed to be nearly identical.
Figure 14. These are the spectral curves for the fifteen pure pigments in Paint Samples. The fifteen color codes at the far right correspond to the pigments selected first row, left to right; second row, left to right; third row, left to right. Each region of interest was selected to contain at least 96 pixels, so the signal to noise has been enhanced by a factor of 10:1 or more for each pigment in these mean spectra. We deliberately chose to put titanium white and zinc white (red and green curves, respectively; pink arrow) and vermilion and cadmium red (blue and yellow curves, respectively; orange arrow) in the composition to show their similarities.
Figure 15. Spectral angle mapping can be tricky. Left: A spectral angle false color map at 0.100 radians tolerance for the canvas (pink), titanium white (yellow), vermilion (red), ultramarine (blue), phthalo green (green), unassigned (black). Right: The same false color map set at 0.200 radians tolerance. Notice that the narrower tolerance is able to distinguish titanium white from zinc white, but it cannot distinguish vermilion from cadmium red; it also does not fully populate the ultramarine and phthalo green areas. The wider tolerance nearly fills the ultramarine and phthalo green areas, still distinguishes titanium white from zinc white, but now begins also confusing Indian yellow for vermilion.
Example Data Sets: Jacob and Aelbert Cuyp; Maerten van Heemskerck
Figure 16. Aelbert Cuyp (1620-1691) and Jacob Gerritsz. Cuyp (1594-1652), Two Children with Cattle in a Landscape and a Shepherd at a Ruin, (1651, oil on canvas, 121.7 x 192.5 cm), Dordrechts Museum, purchased with the support of the Vereniging Rembrandt and Corporate Friends Dordrechts Museum 2009. Photograph reproduced with permission from the Dordrechts Museum.
Analysis of the Cuyp Painting
Figure 17. Maerten van Heemskerck (1498-1574), Saint Luke Painting the Virgin (1532, oil on panel, 168 x 235 cm). Photograph reproduced with permssion from the Frans Hals Museum (photo credit): René Gerritsen.
Figure 18. Low-resolution IR mosaic (multiple tiled images taken at 1620-1700 nm and stitched together computationally) of a portion of the Cuyp painting. The Cuyps made major compositional changes by painting over two cows, significantly changing the position of the girl’s proper right arm, and changing the gaze of the girl. Original art courtesy of the Dordrechts Museum.
Figure 19. Five calibrated, flat-fielded IR images of the “cloud cow” in the Cuyp painting. Top and bottom rows left to right: Bands centered at 975, 1116, 1400, 1520, and 1675 nm. Original art courtesy of the Dordrechts Museum.
Figure 20. Top and bottom rows left to right: MNF bands 1-5 of the cropped “cloud cow” images in the Cuyp painting. Original art courtesy of the Dordrechts Museum.
Figure 21. Top and bottom row left to right: MTMF mean images 1-6 of the “cloud cow” in the Cuyp painting. Original art courtesy of the Dordrechts Museum.
Figure 22. Top and bottom row left to right: SAM rule images 1-6 of the “cloud cow” in the Cuyp painting. Original art courtesy of the Dordrechts Museum.
Figure 23. False color image of “cloud cow” in the Cuyp painting: MNF band 1 was fed into the red channel; MNF band 2 was fed into the green channel; and MNF band 3 was fed into the blue channel. In addition to the cow, the damaged canvas seam becomes very clear. Original art courtesy of the Dordrechts Museum.
Figure 24. False color image of the “cloud cow,” where SAM rule image 1 was fed into the red channel; SAM rule image 2 was fed into the green channel; and SAM rule image 3 was fed into the blue channel. In addition to the cow, the damaged canvas seam becomes very clear. Original art courtesy of the Dordrechts Museum.
Figure 25. Five calibrated, flat-fielded IR images of the girl in the Cuyp painting. Top and bottom rows left to right: Bands centered at 975, 1116, 1400, 1520, and 1675 nm. Note that in the painting underneath the surface painting, the girl’s face is seen in profile. Original art courtesy of the Dordrechts Museum.
Figure 26. Cuyp painting—girl’s face cropped. Left: MNF band 2. Right: MNF band 3. Note that in the painting underneath the surface painting, the girl’s face is seen in profile. Original art courtesy of the Dordrechts Museum.
Figure 27. False color image of the girl’s face in the Cuyp painting, where MNF band 3 was fed into the red channel; MNF band 2 was fed into both the green and blue channels. Note that in the painting underneath the surface painting, the girl’s face is seen in profile. Original art courtesy of the Dordrechts Museum.
Figure 28. A multispectral IR cube taken of the right cow in the Cuyp painting was fully processed. This is a false color image, where MNF band 1 was fed into the red channel; MNF band 2 was fed into both the green and blue channels. Original art courtesy of the Dordrechts Museum.
Figure 29. Top: False color map of Cuyp HSI cube painting detail with spot locations. Red = lead white. Green = vermilion. Chartreuse = vermilion + lead white. Yellow = smalt + lead white. Magenta, white, and cyan = a grayish blue pigment. Original art courtesy of the Dordrechts Museum. Bottom: The corresponding calibrated reflectance spectra (spectral subset from 396-804 nm).
Figure 30. Spectral Angle Maps (0.100 radians). Left: False color map of smalt mixed with lead white (yellow) in the area around the boy. Center: False color map of smalt mixed with lead white (yellow) and the grayish-blue sky paint containing lead white (magenta). The left and center maps are of the exact same pictorial area. Note the tip of the proper left horn of the cloud cow at the right edge of the center color map. Right: False color map of smalt mixed with lead white (yellow) in the area around the underlying cloud cow. Note the canvas seam—the vertical dark line intersecting the cow’s head.
Figure 31. Top: False color map of Cuyp painting detail with spot locations (red and green dots). These spot locations match the locations of pXRF and FORS measurements that were also performed (see main text). Original art courtesy of the Dordrechts Museum. Bottom: The corresponding calibrated reflectance spectra (spectral subset from 396-725 nm). Both curves, particularly the red one, are not inconsistent with aged vivianite mixed with lead white in aged linseed oil, but they are hardly definitive.
Figure 32. FORS spectrum of the false color red spot area of the bodice of the Cuyp girl (Figure 31).
Figure 33. Spectral subset of the 0-40 keV pXRF spectrum of the false color red spot area of the bodice of the Cuyp girl (Figure 31). Given the factors that cause non-uniform sensitivity across the XRF spectral region (especially problematic below 3 keV—these issues are discussed in the previous chapter), this spectrum shows excellent intensity for both iron and phosphorus and is strong evidence for the presence of vivianite. [Note, the Ti and Rh signals are artifacts from the instrument’s construction.]
Analysis of the Heemskerck Painting
Figure 34. Five calibrated, flat-fielded IR images of Mary’s face in the Heemskerck painting. Top and bottom rows left to right: Bands centered at 975, 1116, 1400, 1520, and 1675 nm. Original art courtesy of the Frans Hals Museum.
Figure 35. False color images of Mary’s underlying face in the Heemskerck painting. Left: MTMF mean 3 in the red channel and MTMF mean 5 in the green and blue channels. Right: SAM rule 3 in the red; SAM rule 4 in the green; SAM rule 5 in the blue. Original art courtesy of the Frans Hals Museum.
Figure 36. MNF Band 2 of Mary’s face in the Heemskerck painting. For publication purposes, this image has been subjected to spatial resolution enhancement. Original art courtesy of the Frans Hals Museum.
Conclusion
Experimental
A Note on the Figures
Supplementary Material
Acknowledgments
References
10
10. Mixing Chemistry and Pigments: X-ray Fluorescence Spectroscopy as a Nondestructive Technique for Analysis of Pigments in a Painted Japanese Handscroll • Kathryn L. Rowberg, Grethe Hystad, Matthew L. Clarke, Jazmin Gonzalez, and Johnathon M. Taylor
Introduction
Color Palette of the Kamakura Period
X-ray Fluorescence Spectroscopy
Figure 1. After incident radiation from source ejects an inner K-shell electron, either Kα or Kβ fluorescence may occur and further Lα or Lβ fluorescence may occur. Reproduced with permission from reference 10. Copyright 2021 J. Paul Getty Trust.
Cluster Analysis
Experimental
Figure 2. Representative XRF spectrum of the counts per second versus the energy (in keV) of the fluorescence from the elements Fe, Ni, Cu, Hg, and Pb, with colored vertical lines notating transitions. The red trace is the data, and the blue trace is the deconvoluted spectrum.
Results and Discussion
Copper with Zinc Background
Figure 3. Element maps and clusters for Woman. (a) The painted scene (expanded slightly on left and right; Freer Gallery of Art, Smithsonian Institution, Washington, DC: Gift of Charles Lang Freer, F1907.375a (detail) / Department of Conservation and Scientific Research, Photograph by Jiro Ueda). (b) Copper (green) element map with mercury (red) for orientation. (c) Zinc (orange) element map shows diffuse presence. (d) Four clusters plotted along the coordinates of Woman. (e) Band intensity scatter plot of the zinc and copper XRF Kα1 line intensities from each point with the four clusters assigned by color and shape as seen in the legend. The proximity of Figures 3b and 3d allows for ease of comparison.
Figure 4. Element and cluster maps for Seated Man. (a) The painted scene (Freer Gallery of Art, Smithsonian Institution, Washington, DC: Gift of Charles Lang Freer, F1907.375a (detail) / Department of Conservation and Scientific Research, Photograph by Jiro Ueda). (b) Copper (green) element map. (c) Zinc (orange) element map. (d) Clusters plotted in the coordinates of Seated Man. (e) Band intensity scatter plot of the zinc and copper XRF Kα1 line intensities from each point with select clusters assigned by color and shape per the legend. The proximity of Figures 4b and 4d allows for ease of comparison.
Copper with Coincident Zinc
Copper with Coincident Zinc in Unique Ratios
Figure 5. Element and cluster maps for Man. (a) The painted scene (Freer Gallery of Art, Smithsonian Institution, Washington, DC: Gift of Charles Lang Freer, F1907.375a (detail) / Department of Conservation and Scientific Research, Photograph by Jiro Ueda). (b) Copper (green), mercury (red) and zinc (orange) element maps overlayed. (c) Zinc (orange) and mercury (red) element maps overlayed. (d) Clusters plotted in the coordinates of Man. (e) Band intensity scatter plot of the zinc and copper XRF Kα1 line intensities from each point with clusters 1)-4) assigned by color and shape per the legend. The proximity of Figures 5b and 5d allows for ease of comparison.
Conclusion
Acknowledgments
References
Study Abroad
11. Development and Implementation of Molecular Modernism, a “Chemistry and Art” Course with Travel Components in France or the United States • Jeffrey E. Fieberg
Introduction
Motivation to Develop a Chemistry in Art Course with a Travel Component
Course Considerations
Course Commonalities
Subject Matter
Art History: Realism to Abstraction
Figure 1. Representative paintings for teaching art history from Realism to Abstraction in “Molecular Modernism.” (A) Gustave Courbet, The Rock of Hautepierre, 1869. The Art Institute of Chicago, (B) Claude Monet, Woman with a Parasol - Madame Monet and Her Son, 1875. National Gallery of Art, Washington, (C) Georges Seurat, A Sunday on La Grande Jatte—1884, 1884/6. The Art Institute of Chicago, (D) Vincent van Gogh, Le café de nuit (The Night Café), 1888. Yale University Art Gallery, (E) Paul Cézanne, Mont Sainte-Victoire, 1902-6. The Metropolitan Museum of Art, New York, (F) Henri Matisse, Open Window, Collioure, 1905. Oil on canvas, overall: 55.3 x 46 cm (21 3/4 x 18 1/8 in.) framed: 71.1 x 62.2 x 5.1 cm (28 x 24 1/2 x 2 in.). Collection of Mr. and Mrs. John Hay Whitney, National Gallery of Art, Washington 1998.74.7. Reproduced with permission from Copyright 2021 Succession H. Matisse / Artists Rights Society (ARS), New York, (G) Pablo Picasso, Daniel-Henry Kahnweiler, 1910. The Art Institute of Chicago, autumn 1910. Oil on canvas, 39 9/16 x 28 9/16 in. (100.4 x 72.4 cm). Gift of Mrs. Gilbert W. Chapman in memory of Charles B. Goodspeed, 1948.561. Photo Credit: The Art Institute of Chicago / Art Resource, NY. Reproduced with permission from Copyright 2021 Estate of Pablo Picasso / Artists Rights Society (ARS), New York, (H) Wassily Kandinsky, Improvisation No. 30 (Cannons), 1913. The Art Institute of Chicago, (I) Piet Mondrian, Lozenge Composition with Yellow, Black, Blue, Red, and Gray, 1921. The Art Institute of Chicago. (A), (B), (C), (D), (E), (H) and (I) distributed under a Creative Commons Public Domain Dedication CC0 1.0 https://creativecommons.org/publicdomain/zero/1.0/.
Scientific Topics
Figure 2. Interaction of regions of the electromagnetic spectrum with various strata of an oil painting on canvas. (adapted with permission from Pat Hill).
Figure 3. Pigments available to the Impressionists. Each modern, synthetic pigment is marked with an asterisk to illustrate the profound impact of synthetic chemistry on 19th and 20th century paintings.
Interdisciplinary Topics
Case Studies
Case Study 1: Renoir, Luncheon of the Boating Party, 1880-1, Phillips Collection, Washington D.C. (2830)
Figure 4. (A) Pierre-Auguste Renoir, Luncheon of the Boating Party, between 1880 and 1881. Oil on canvas, 51 ¼ x 69 1/8 in., The Phillips Collection, Washington, DC. Acquired 1923. (B) X-radiograph, (C) paint cross section taken from Aline Charigot’s dress, (D) infrared reflectogram, (E) detail of still life in raking light, and (F) infrared reflectogram of detail in (E) (2829). Images courtesy of The Phillips Collection.
Case Study 2: Van Gogh’s Undergrowth with Two Figures, Cincinnati Art Museum, 1890, Analysis Performed in Conservation Science Laboratory at Indianapolis Museum of Art 36.
Figure 5. Raman spectrum of (A) red pigment agglomerates in Van Gogh paint sample compared to those of (B) a reference sample of eosin Y and (C) lead(II) sulfate. The spectra are superimposed over a paint sample that shows dirt, varnish and wax residue at the top, ~50-60 microns of faded (white) paint, under which the bright pink original paint remains.
Figure 6. Microfocus XRF spectrum of the pink area in a paint cross section that shows the Br signal from eosin in Van Gogh’s geranium lake paint.
Case Study 3: Renoir, The Umbrellas, National Gallery, London (273940)
Figure 7. Digital reconstruction of the faded pink flowers based on MXRF analysis for Vincent van Gogh, Undergrowth with Two Figures, 1890, oil on canvas, Cincinnati Art Museum, Bequest of Mary E. Johnston, 1967.1430.
Figure 8. (A) Pierre-Auguste Renoir, The Umbrellas (NG 3268), c. 1881-6. Oil on canvas, 180.3 x 114.9 cm, The National Gallery, London. (B) Digitally processed X-radiograph, (C) infrared reflectogram, (D) cross-section from the chestnut-brown hair of the young woman to the left showing the purple-red paint of the earlier (stage 1) hat beneath the surface. Images courtesy of the National Gallery, London.
Case Study 4: Georges Seurat, A Sunday on La Grande Jatte—1884, Art Institute of Chicago (4344)
Figure 9. a) Georges Seurat, A Sunday on La Grande Jatte—1884, oil on canvas, Helen Birch Bartlett Memorial Collection, The Art Institute of Chicago, AIC# 1926.224; b) Photomicrograph of discolored ochre-colored and olive green dots at juncture between shadowed and sunlit grass in the middle ground at far right; c) vials containing modern powders of the pigments emerald green (at left) and zinc yellow, illustrating the original color of the unaltered pigments. Reproduced with permission from reference 44. Copyright (2010) Springer-Verlag, Inc.
Figure 10. (A) Reflectance curves of average measurements of orange dots, before and after undarkening, and the spectral match using zinc yellow, vermilion, and lead white. (B) Visualization of these dots and average in situ color (top to bottom). Reproduced with permission from reference 43. Copyright (2006) Wiley Periodicals, Inc.
Case Study 5: Giorgio de Chirico, The Mysterious Departure, 1930s, Indianapolis Museum of Art at Newfields (5354)
Figure 11. Detail of A Sunday on La Grande Jatte, before (top) and after (bottom) digital rejuvenation. Reproduced with permission from reference 43. Copyright (2006) Wiley Periodicals, Inc.
Figure 12. Giorgio de Chirico (Italian, 1888–1978), The Mysterious Departure, about 1930–1933, oil on canvas, 21-7/16 × 27-1/2 in., 29 × 35 in. (framed). Sampling locations (in situ and excised) for spectroscopic examination by XRF, SEM-EDS, Raman and FTIR. Reproduced with permission from Indianapolis Museum of Art at Newfields, Bequest of Mrs. James W. Fesler, 61.40 Copyright 2021 Estate of Giorgio de Chirico / Artists Rights Society (ARS), NY.
Figure 13. X-radiograph of The Mysterious Departure. Courtesy of Newfields.
Additional Case Studies
Course Materials
Classroom Demonstrations
Assignments
Reading Questions
Elements of Art
Google Arts & Culture Project
Student Class Presentations
Dry Laboratory Forgery Investigation of a Purported Giorgio de Chirico Painting
Background into Logistics and Learning Opportunities Unique to Each Course
Semester-Long Study Abroad Course in Strasbourg, France: “Molecular Modernism: Manet to Marc”
Figure 14. Students (A) enjoying escargots at La Bonne Franquette in Montmartre, (B) relaxing with Monet’s Water Lilies in the Musée l’Orangerie, and (C) presenting on Caillebotte’s relationship with his fellow Impressionists in the Musée d’Orsay.
Figure 15. A spring 2018 student presents on Dada and Jean Arp in the Musée d’Art Moderne et Contemporain, Strasbourg.
Figure 16. Spring 2018 Molecular Modernism students in Kandinsky’s Salon de Musique at the Musée d’Art Moderne et Contemporain in Strasbourg.
Figure 17. Spring 2014 visit to Aubette 1928, the “Sistine Chapel of Abstract Art 14,” with students “in the painting” of the salle des fêtes.
Three-Week January Term Study Abroad Course in Paris and Provence, France: “Molecular Modernism: Manet to Matisse”
Figure 18. Students in 2013 January Term course at (A) C2RMF at the Louvre with Nathalie Balcar, Conservation Scientist, and (B) the Ecole Supérieure d’Art d’Avignon observing conservation of tattooed human skin.
Figure 19. (A) Author discusses Pissarro’s View of Marly-le-Roi, 1870, private collection, at Domaine National de Marly on the Trail of the Impressionists in 2013, (B) Centre students pose as models in January 2017 on the balcony at La Maison Fournaise to recreate Renoir’s masterpiece, Luncheon of the Boating Party, 1880-1, The Phillips Collection.
Figure 20. CentreTerm 2013 students at painting site of Van Gogh’s Church at Auvers, Musée d’Orsay, 1890.
Figure 21. CentreTerm 2017 students at Cézanne’s “painter’s grounds” in Aix-en-Provence with Mont Sainte-Victoire in the background. Half of the group hiked with the author to the summit of Mont Sainte-Victoire on their free day.
Three-Week First-Year Seminar Course with Domestic Travel Component: “Molecular Modernism: Monet to Mondrian”
Conclusion
Acknowledgments
Appendix A. Subject Matter
Art Historical Subject Matter
Questions Posed and Answered
Important Events That Shape Art History and “Molecular Modernism”
Scientific Topics
Questions Posed and Answered
Interdisciplinary Topics
Questions Posed and Answered
Interdisciplinary Topics
Appendix B. Course-Specific Student Presentations
Molecular Modernism: Manet to Marc, Semester Course in Strasbourg, France
Molecular Modernism: Manet to Matisse, Three-Week January Term Study Abroad Course in Paris and Provence, France
Linked Presentations #1 and #2
“Capstone” Scientific Analysis of a Painting
Van Gogh Group Presentation
Molecular Modernism: Monet to Mondrian, Three Week First-Year Seminar
Presentation #1: Pigments Paired with Impressionist
Presentation #2: Choice of a) Analytical Technique Used in Conservation Science, b) Art Historical Issue, or c) “Molecular Modernism” Interdisciplinary Topic
Presentation #3: Capstone Scientific Analysis of a Painting
References
12
12. Exploring London through the World of Art and Chemistry: The Properties and Uses of Metals in Sculpture • Lynn M. Bradley and Elizabeth Mackie
Course History and Evolution
Course Description
Course Scheduling and Organization
Chemistry Laboratory Activities, Art Workshops, Lectures, and Pre-trip Assignments
Planning the Trip to London
London Site Visits
Course Assignments
Durability Worksheet
Case Studies
Laboratory Activities
London Art and Chemistry Presentation
Tate Modern Materials Exhibit
Scavenger Hunt
London Journal
Map of London
Figure 1. Exhibition of Student Map Project by Dylan Nguyen, TCNJ Art Gallery. Ten art sites are represented by maps in the shape of tea bags and an included booklet explains the art and chemistry for each location.
Methods of Assessment
Metals – Background Information and Course Content
Introductory Concepts
Metals and Their Uses in Art - Lecture Content
Pure Metals
Metals from Compounds
Figure 2. Aluminum. Interesting note: One of the first statues to be cast in aluminum was made in 1893; the statue of Eros can be found in Piccadilly Circus in London.
Alloys
Figure 3. Bronze.
Figure 4. Painted steel.
Figure 5. Textured stainless steel.
Figure 6. Brushed stainless steel.
Figure 7. COR-TEN TM steel.
Figure 8. COR-TEN TM steel.
Processes
Figure 9. Galvanized steel.
Figure 10. Copper patina.
Figure 11. Bronze patina.
Figure 12. Bronze patina.
Interesting Properties of Metals and Their Uses in Creative Fields
Laboratory Activities
London Activities Relating to Metals
Case Studies from The College of New Jersey (Projects in Which Chemical and Material Properties Enhance Art Production)
Figure 13. (A) Installation view of final exhibition of Address the River. (B) Welded steel wireframe support structure for fabric dress. (C). Lily Gilston grinding the welded metal joints.
Figure 14. (A) Detail. (B) Installation view of Bed of Rapunzel.
Figure 15. Whispering Mountain.
Case Studies Representing International Artists
Teaching Resources - Course Resources
Artists Working in Metals
Suggested Sculpture Parks in the United States
Some Impressive University and College Public Art Collections
Conclusion
Acknowledgments
Appendix
Resources for the Metal Experiments Discussed in the Chapter
1 Tarnish Removal - List of Chemicals and Materials:
2 Niobium Anodization - List of Chemicals and Materials:
3 Verdigris - List of Chemicals and Materials:
References
Interdisciplinary or Multiple Levels
13. Dry Laboratory Forgery Investigation of a Purported Giorgio de Chirico Painting for a “Chemistry in Art” Course • Jeffrey E. Fieberg and Gregory D. Smith
Introduction
Figure 1. Giorgio de Chirico (Italian, 1888–1978), The Mysterious Departure, about 1930–1933, oil on canvas, 21-7/16 × 27-1/2 in., 29 × 35 in. (framed). Reproduced with permission from Indianapolis Museum of Art at Newfields, Bequest of Mrs. James W. Fesler, 61.40 Copyright 2021 Estate of Giorgio de Chirico / Artists Rights Society (ARS), NY.
Figure 2. JEF performing Raman analysis of pigments in situ for The Mysterious Departure.
Art Historical Background
Figure 3. Examples of Giorgio de Chirico’s early metaphysical, pre-Surrealist work. (A) The Philosopher’s Conquest. 1913/14. Oil on canvas, 125.1 x 99.1 cm (49 1/4 x 39 in.). Joseph Winterbotham Collection, 1939.405, The Art Institute of Chicago / Art Resource, NY, (B) Gare Montparnasse (The Melancholy of Departure). Paris, early 1914. Oil on canvas, 55 1/8" x 6' 5/8" (140 x 184.5 cm). Gift of James Thrall Soby, Digital Image Copyright The Museum of Modern Art/Licensed by SCALA / Art Resource, NY, (C) The Enigma of a Day. Paris, early 1914. Oil on canvas, 6' 1 1/4" x 55" (185.5 x 139.7 cm). James Thrall Soby Bequest. Copyright Artists Rights Society (ARS), New York / SIAE, Rome, Digital Image Copyright The Museum of Modern Art/Licensed by SCALA / Art Resource, NY. All images are reproduced with permission from Copyright 2021 Estate of Giorgio de Chirico / Artists Rights Society (ARS), NY.
Figure 4. Representative examples of de Chirico’s 1920s and 1930s neoclassical style. (A) Ancient Horses (Cavalli antichi), 1928, oil on canvas. Photo: Alessandro Vasari, Galleria Nazionale d’arte Moderna, Rome, Italy, Mondadori Portfolio / Art Resource, NY, (B) Diana sleeping in the Wood (Diana addormentata nel bosco), 1934, oil on canvas, 89 x 116,5 cm. Photo: Alessandro Vasari, Galleria Nazionale d’arte Moderna, Rome, Italy, Mondadori Portfolio / Art Resource, NY, (C) Bathers on the Beach, 1934, Galleria Nazionale d’arte Moderna, Rome, Italy. Reproduced with permission from the Ministero dei beni e delle attività culturali e del turismo. All three images are reproduced with permission from Copyright 2021 Estate of Giorgio de Chirico / Artists Rights Society (ARS), NY.
Description of the Activity
Synopsis
Pre-laboratory Introduction
Exhibits 1-4
Imaging Techniques
Raking Light
Figure 5. Interrogation of painting strata by electromagnetic radiation. Adapted with permission from class slide by Pat Hill, Millersville University.
Figure 6. Raking light reveals texture. Courtesy of Newfields.
Figure 7. Raking light images. Courtesy of Newfields.
Information Relevant to Forgery Assignment:
X-Radiograph
Information Relevant to Forgery Assignment:
Ultraviolet-Induced Visible Fluorescence (UVF) Photograph
Figure 8. Ultraviolet-induced visible fluorescence (UVF) photograph with emphasis on two dark, inpainted areas on the white building. Courtesy of Newfields.
Information Relevant to Forgery Assignment:
Infrared Reflectogram
Figure 9. Greater contrast in the infrared transmittogram (rotated 180°) provides a more distinct image of the female nude, including her grip of a draped cloth. Courtesy of Newfields.
Information Relevant to Forgery Assignment:
Labels on Verso and Exhibition Catalog
Information Relevant to Forgery Assignment:
Spectroscopic (Chemical) Techniques for Pigment Identification
X-ray Fluorescence (XRF) Spectroscopy
Information Relevant to Forgery Assignment:
Raman Spectroscopy
Figure 10. Raman spectra of (A) green window, chrome yellow and Prussian blue and (B) comparison of green window with blue sky.
Information Relevant to Forgery Assignment:
Analysis of Excised Sample from Yellow Plaza by FTIR Microspectroscopy, SEM-EDS, and Raman
Figure 11. Analysis of excised sample (EX 3, yellow plaza) by (A) SEM-EDS, (B) Raman spectroscopy and (C) FTIR spectroscopy.
Information Relevant to Forgery Assignment:
Palette for The Mysterious Departure as Determined by XRF, SEM-EDS, Raman and IR Spectroscopies
Conclusion of the Lab Activity—Written Reports and Presentations
Figure 12. Self-Portrait in the Parisian Studio (Autoritratto nello studio di Parigi), 1934-1935, oil on canvas, 130 x 76 cm. Photo: Alessandro Vasari, Galleria Nazionale d’Arte Moderna, Rome, Italy, Mondadori Portfolio / Art Resource, NY. Reproduced with permission from Copyright 2021 Estate of Giorgio de Chirico / Artists Rights Society (ARS), NY.
Figure 13. (A) Centre College students at the IMA with The Mysterious Departure in the gallery with JEF and (B) on a tour of the Conservation Science Laboratory with GDS.
Conclusion
Acknowledgments
Appendix: Student Lab Packet
Figure A1. Giorgio de Chirico (?) (Italian, 1888–1978), The Mysterious Departure, oil on canvas, 21-7/16 × 27-1/2 in., 29 × 35 in. (framed). Reproduced with permission from Indianapolis Museum of Art at Newfields, Bequest of Mrs. James W. Fesler, 61.40.
Figure A2. Exhibit 1. Painting purchased by Mrs. James Fesler for $2500.00 in 1944 from art dealer, Theodore Schempp, of New York. Courtesy of Newfields.
Figure A3. Exhibit 2. History of Giorgio de Chirico forgeries.
Figure A4. Exhibit 3. Letter from de Chirico scholar that pronounced the painting a forgery. Courtesy of Newfields.
Figure A5. De Chirico’s oeuvre from pre-Surrealist 1910s to neoclassical 1930s.
Figure A6. Raking light images. Courtesy of Newfields.
Figure A7. X-radiograph. Courtesy of Newfields.
Figure A8. Ultraviolet-induced visible fluorescence (UVF). Courtesy of Newfields.
Figure A9. Infrared reflectogram. Courtesy of Newfields.
Figure A10. Verso of The Mysterious Departure. Courtesy of Newfields.
Figure A11. Left label on verso. Courtesy of Newfields.
Figure A12. Right label on verso. Courtesy of Newfields.
Figure A13. Pages 1 and 4 of brochure from exhibition of de Chirico’s paintings and drawings in Prague, Czechoslovakia in 1935. Reproduced with permission from Archive of Fine Arts, Prague (www.artarchiv.cz)).
Figure A14. Sampling locations (in situ and excised) for spectroscopic examination by XRF, SEM-EDS, Raman and FTIR. Courtesy of Newfields.
References
14
13. Teaching Undergraduate Chemistry through Fibers and Dyes • Angela G. King and Annelise H. Gorensek-Benitez
Introduction
CHM 351: Fibers and Dyes at Wake Forest University
Overview of the Course
Introduction to Fiber Arts and Campus Resources
Figure 1. A 3D printed potholder loom and cotton loops offer an affordable avenue for community outreach by combining science and art.
Natural Dyes and Techniques
Figure 2. Blank table used for dyeing with mordants (A) and student group results for mordanted wool with several natural dyes (B).
Figure 3. A student observes the oxidation reaction producing the blue color of indigo dye. Students compared fabric dyed with synthetic and natural indigo.
Synthetic Dyes
Figure 4. A synthetic scheme for producing a developed dye.
Community Outreach and Creative Projects
Figure 5. Students presenting their final projects for the course, in which they were tasked with using any fiber arts technique and any combination of fibers and dyes to create a work of art that reflected the theme “Chemistry: The Key to a Colorful Fabric of Life”.
Assessment and Reflection
Figure 6. A sample question on an exam. Students used their understanding of chemical structures and dyes to classify some dye molecules they had not yet seen in the course.
CHE 106: Dyeing to Learn Chemistry at Davidson College
Overview
Figure 7. Supplies for mordant lab (A), time and concentration lab (B), both labs (C), and the QR codes for students to access the pictures (D).
Overview of Take-Home Laboratory Kits
Time and Concentration Laboratory
Figure 8. Sample results from time and concentration experiment, including sample yarns (A) and multifiber test strips (B).
Spectrophotometry Laboratory
Figure 9. Excerpt from handout given to students during the spectrophotometry lab. Spectra of single colors (A-C), spectra of 2-color mixes (D-F), cuvettes containing 2-color mixes (G).
Madder and pH Laboratory
Figure 10. Data from virtual Madder and pH lab.
Figure 11A. Sample exercises from the 1st page of the Madder and pH laboratory report.
Figure 11B. Sample exercises from the 2nd page of the Madder and pH laboratory report.
Chemistry and Real World Applications
Incorporating the Work of Black, Indigenous and People of Color (BIPOC) Makers and Scientists
Figure 12. Sample problem from an exam, Spring 2020.
Literature Research Project
Assessment and Reflection
Recommended Resources for Instructors
Conclusions
Acknowledgments
References
15
15. Integrating Archaeology and Interdisciplinary Collaborations with Museums into the Chemistry Curriculum • Kevin L. Braun
Introduction
Why Have Metals Been Used through the Ages?: A General Chemistry Activity for Majors and Nonmajors
Figure 1. Why have metals been used through the ages? worksheet used within a general chemistry course for majors and nonmajors.
Teaching Instrumentation through the Lens of Archaeology
Updated Archaeological Pottery Residue Analysis Laboratory
Archaeological and Museum Conservation Applications of XRF Spectroscopy
Figure 2. The benchtop pXRF setup used in a 2016 collaboration with the Logan Museum of Anthropology, Beloit, WI. Photo by K. L. Braun.
Figure 3. Close-up of beadwork covered with white powder on a Chiricahua Apache buckskin dress. XRF analysis showed presence of arsenic on the beads but not on the buckskin thus indicating that the dress had not been treated with an arsenic based pesticide. Glass disease was determined to have produced the white powder. Photo by K. L. Braun.
Archaeological Chemistry as an Advanced Topics Course
Course Structure and Assignments
Figure 4. Archaeological chemistry schedule.
Museum Laboratory
Figure 5. Students acquiring surface swabs from three artifacts from the VMI Museum, Lexington, VA. to test for the presence of transferable arsenic. Arsenic was commonly used in the preservation of taxidermy mounts and to protect artifacts against vermin. VMI photos by Kelly Nye.
Figure 6. Sample analysis requires students to convert any transferable arsenic on the swab samples to arsine gas (A) which reacts and darkens mercury bromide infused paper suspended in the test tube (B). In B, Sample 5 was collected from the bottom of the saddle fender in Figure 4A while Sample 6 was collected from the middle of the inner side of the saddle fender and can be seen being collected in Figure 4A. The darkening of the mercury bromide paper in Sample 6 indicates the presence of transferable arsenic. Photos by K. L. Braun.
Conclusion and Assessment
Conclusion
Acknowledgments
References
16
16. An Introduction to Ceramic Glaze Color Chemistry • Jennifer L. Wicks and Ryan H. Coppage
Introduction
Absorbance and Reflectance
Figure 1. An exaggerated spetral example of Incident light (left) vs. absorbance (middle) vs. reflectance (right).
Figure 2. Examples of three distinctively different reflectance profiles from glaze color with the top, iron, showing red, the bottom, showing copper and cobalt content for a blue-green, and the middle showing almost no color, as black – also from iron content.
Figure 3. A graphical example of incident light interacting with reflected light and different mediums to produce reflectance and thus color.
Ceramic Glaze Color Centers
Figure 4. Various illustrations for crystal field theory, including a metal cation inside an octahedral coordination environment (a), the dx2-y2 orbital around a metal cation (b), and a metal cation and dx2-y2 orbital inside an octahedral coordination environment (c).
Figure 5. Various illustrations for crystal field theory, including a metal cation inside a tetrahedral coordination environment (a), the dx2-y2 orbital around a metal cation (b), and a metal cation and dx2-y2 orbital inside a tetrahedral coordination environment (c).
Figure 6. Diagrams for the splitting pattern for d-orbitals for a d2 transition metal, for an octahedral environment (a) and a tetrahedral environment (b).
Figure 7. A diagram for the splitting pattern for d-orbitals for a d2 transition metal, in which light strikes a low-lying electron, is absorbed by that electron, and the electron is promoted to a higher energy, empty orbital.
Figure 8. A reflectance spectrum for a celadon glaze base with 0.5% cobalt carbonate. This illustrates a possible electron promotion event (and absorption of light for that to take place) for a d7 metal in an octahedral coordination and the refected light responsible for the glaze color.
Shifting Absorption Wavelengths
Figure 9. Tile samples of various glaze colors, including pigments (top row, left to right) chromium (III) oxide (a), chromium (III) oxide with tin (IV) oxide (b), cobalt carbonate (c), erbium oxide(d), red iron oxide(e), (bottom row, left to right) rutile (titanium dioxide with an iron oxide impurity, (f)), praseodymium (III) oxide (g), holmium (III) oxide (h), copper carbonate (i), and manganese dioxide (j).
Figure 10. A celadon base glaze (cone 6, oxidation) with 0.5 % copper (II) carbonate pigment (tile a) and 1.0% copper carbonate pigment (tile b), which results in reflectance spectra a and b, respectively.
Figure 11. A glaze base with 0.2% chromium (III) oxide pigment in it across all samples, fired to cone 6 in oxidation. From left to right, tin (IV) oxide is added in 0, 2, 4, and 6 % amounts, by weight.
Figure 12. A glaze base with 0.2 % chromium (III) oxide (by weight), left (fired to cone 6 in oxidation), and respective reflectance spectra, right, are shown for the addition of 0, 2, 4, and 6 % tin (IV) oxide, for samples a, b, c, and d, respectively.
Figure 13. A “Panama Red” glaze with 1.75 % (by weight) copper (II) carbonate pigment and 2.6 % tin (IV) oxide was fired in oxidation to cone 6 (a) and in reduction to cone 10 (b).
Glaze Profiles
Figure 14. A diagram of likely behaviors of light as it strikes the surface (1), travels through a translucent glaze profile (2), reflects off the glaze-ceramic interface (3), and is transmitted back out of the glaze as a final “reflectance” of colored light.
Figure 15. A diagram of likely behaviors of light as it strikes the surface (1), travels through an opaque glaze profile (2), reflects off an opaque, crystalline particle suspended in the glaze (3), and is transmitted back out of the glaze as a final “reflectance” of colored light.
Guided Glaze Experiments
Conclusions
References
17
17. The Heterogeneity Problem: Intermolecular Forces as They Relate to Solubility and Chromatography • Joseph F. Lomax and Suzanne Q. Lomax
Introduction
Figure 1. The partly cleaned face of the Virgin Mary in a detail of The Annuciation by Antoniazzo Romano or Evangelista Aquili from the Vatican Museums. The varnish has been removed on the proper right side of the Virgin’s face. (Photo by authors; reproduced with permission of the Vatican Museums.)
Figure 2. A painting of Cain and Abel with varnish and inpainting removed 1. (Photo by authors; reproduced with permission of the Vatican Museums.)
Horror Impar Insimularet (Nature Abhors an Unbalanced Charge)
Symmetry
Eight Questions on Symmetry, Dielectric Constants and Solubility
1) If Totally Symmetric Molecules Are Non-polar, Why Is Their Dielectric Constant above 1?
2) What Is the Consequence of Interactions between Electrons Moving around a Totally Symmetric Molecule?
3) Hexane and Benzene Are Not Totally Symmetric; Why Are Their Dielectric Constants So Low?
Figure 3. Illustration of hydrogen saturation.
Figure 4. Some conformers of n-hexane.
Solubility and the Heterogeneity Question: Crops and Weeds
4) Why Are the Dielectric Constants of Methanol and Water So High, and Diethyl Ether Is Low?
5) How Are Vapor Pressure and Boiling Point Related to IMF’s?
IMF’s, Vapor Pressure, Boiling Point and Lab Safety
6) Can We Use the Different Types of Molecular Forces to Predict How Well Things Dissolve?
Figure 5. Solvent and solute. Expansion, to mixing, to solution 13.
Figure 6. Examples of Teas plots (Figures 1, 2, and 3 of reference 17). Reproduced with permission from reference 17. © 1997, The Building Conservation Directory.
Assessment: Short Answer Essay Questions.
7) How Is That Water, a Covalently Bonded Molecule, Can Dissolve Ionic Compounds?
8) How Does a Soap or Detergent Work?
Figure 7. Stearic acid with hydrophilic and hydrophobic parts labeled.
Figure 8. Micelles a) typical micelle formed in aqueous environment, b)inverted micelle formed in hydrophobic environments 26.
Chromatography: The Tool of Separation Science
Figure 9. Paper chromatography of Pentel Arts® Sign Pens® a) water before, b) water after, c) ethanol after. Lower viscosity of ethanol allows the solvent to travel up paper more rapidly.
The Heart of Chromatography
On the Way to High Performance
Gas Chromatography
Figure 10. Schematic of gas chromatograph/mass spectrometer 38. Reproduced with permission from Reference 38. Copyright Dunnivant & Ginsbach.
Detection Using Mass Spectrometry
Figure 11. Schematic of a typical mass spectrometer using a magnetic sector detector.
An Example from Art Conservation
Figure 12. Transfluent Lines, Rice Pereira, 1946 41. © Estate of I. Rice Pereira / Artists Rights Society (ARS), New York.
GC/MS: Gas Chromatography
Figure 13. Rice Pereira, Transfluent Lines, 1946, a) chromatogram of white paint sample, b) chromatogram of ocher paint, c) mass spectrum of peak eluting at 29.49 minutes on chromatogram b. (labeled with arrow) 45.
GC/MS: Mass Spectrometry
Summary of Chromatography and Mass Spectrometry
Summary of Heterogeneity, Solubility and Chromatography
Acknowledgements and Assessment
References
Editors’ Biographies
Kevin L. Braun
Kristin Jansen Labby
Indexes
Author Index
Subject Index
A
C
F
G
H
M
P
T
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Contextualizing Chemistry in Art and Archaeology: Inspiration for Instructors
ACS SYMPOSIUM SERIES 1386
Contextualizing Chemistry in Art and Archaeology: Inspiration for Instructors Kevin L. Braun, Editor Virginia Military Institute Lexington, Virginia, United States
Kristin Jansen Labby, Editor Beloit College Beloit, Wisconsin, United States
Sponsored by the ACS Division of Chemical Education
American Chemical Society, Washington, DC
Library of Congress Cataloging-in-Publication Data Names: Braun, Kevin L., editor. | Labby, Kristin Jansen, editor. Title: Contextualizing chemistry in art and archaeology : inspiration for instructors / Kevin L. Braun, Virginia Military Institute, Lexington, Virginia, United States, Kristin Jansen Labby, Beloit College Beloit, Wisconsin, United States, editors. Description: Washington, DC : American Chemical Society, [2021] | Series: ACS symposium series; 1386 | "Sponsored by the ACS Division of Chemical Education." | Includes bibliographical references and index. Identifiers: LCCN 2021042038 (print) | LCCN 2021042039 (ebook) | ISBN 9780841298330 (hardcover) | ISBN 9780841298323 (ebook other) Subjects: LCSH: Chemistry--Study and teaching. | Art--Study and teaching. | Archaeology--Study and teaching. Classification: LCC QD40 .C897 2021 (print) | LCC QD40 (ebook) | DDC 540.71--dc23/eng/20211005 LC record available at https://lccn.loc.gov/2021042038 LC ebook record available at https://lccn.loc.gov/2021042039
The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials, ANSI Z39.48n1984. Copyright © 2021 American Chemical Society All Rights Reserved. Reprographic copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Act is allowed for internal use only, provided that a per-chapter fee of $40.25 plus $0.75 per page is paid to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. Republication or reproduction for sale of pages in this book is permitted only under license from ACS. Direct these and other permission requests to ACS Copyright Office, Publications Division, 1155 16th Street, N.W., Washington, DC 20036. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. Registered names, trademarks, etc., used in this publication, even without specific indication thereof, are not to be considered unprotected by law. PRINTED IN THE UNITED STATES OF AMERICA
Foreword The ACS Symposium Series is an established program that publishes high-quality volumes of thematic manuscripts. For over 40 years, the ACS Symposium Series has been delivering essential research from world leading scientists, including 36 Chemistry Nobel Laureates, to audiences spanning disciplines and applications. Books are developed from successful symposia sponsored by the ACS or other organizations. Topics span the entirety of chemistry, including applications, basic research, and interdisciplinary reviews. Before agreeing to publish a book, prospective editors submit a proposal, including a table of contents. The proposal is reviewed for originality, coverage, and interest to the audience. Some manuscripts may be excluded to better focus the book; others may be added to aid comprehensiveness. All chapters are peer reviewed prior to final acceptance or rejection. As a rule, only original research papers and original review papers are included in the volumes. Verbatim reproductions of previous published papers are not accepted. ACS Books
Contents Preface–Chemistry’s Diverse Applications in Art and Archaeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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General Chemistry 1. Incorporating Conservation Science into the General Education Curriculum . . . . . . . . . . . . . . Joan M. Esson
3
2. Archaeological and Historical Pigments: A Unifying Framework for Delivering Relevant Chemical Content Utilizing an Interdisciplinary Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Christopher R. Vyhnal and Roxanne Radpour 3. Connecting Chemistry and Cultural Heritage: Presenting the Physical Sciences to Non-science Majors and First-Year Students through the Investigation of Works of Art and Archaeological Artifacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Citlalli Rojas Huerta and Maria Parr 4. Using Examples from Art and Archaeology to Demonstrate the Chemistry of Materials in a General Education Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Jennifer E. Mihalick 5. Using the History of Technology to Connect Art and Chemistry in a Science of Art Course for Nonscience Majors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Brian McBurnett 6. Making Light Work: A First-Year Writing Course on Art, Colors, and Chemistry . . . . . . . . 97 Benjamin J. McFarland Instrumentation 7. The Chemistry of Art and Artifacts: A Sophomore-Level, Thematic Chemical Instrumentation Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Kristin Jansen Labby 8. X-ray Fluorescence Spectroscopy in Painting Analyses: Undergraduate Classroom, Teaching Laboratory, and Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Erich S. Uffelman, Liesbeth Abraham, Andrea Abry, Nicholas Barbi, Harris Billings, Sydney Collins, Sam Florescu, Christina Kargol, Jorinde Koenen, Mireille te Marvelde, Jennifer L. Mass, Leo Mazow, Daniel Monteagudo, Kathryn Muensterman, Carol W. Sawyer, Kate Seymour, and Mallory Stephenson vii
9. Multispectral and Hyperspectral Reflectance Imaging Spectrometry (VIS, VNIR, SWIR) in Painting Analyses: Undergraduate Teaching and Interfacial Undergraduate Research at the Nexus of Chemistry and Art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Erich S. Uffelman, Liesbeth Abraham, John P. Davis, John K. Delaney, Kathryn A. Dooley, Lindsey Hewitt, Jorinde Koenen, Mireille te Marvelde, Kathryn Muensterman, Konstantinos Oikonomou, Darcy Olmstead, Trinity Perdue, Jensen Rocha, Jessica Roeders, Annika Roy, and Lidwien Speleers 10. Mixing Chemistry and Pigments: X-ray Fluorescence Spectroscopy as a Nondestructive Technique for Analysis of Pigments in a Painted Japanese Handscroll 217 Kathryn L. Rowberg, Grethe Hystad, Matthew L. Clarke, Jazmin Gonzalez, and Johnathon M. Taylor Study Abroad 11. Development and Implementation of Molecular Modernism, a “Chemistry and Art” Course with Travel Components in France or the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Jeffrey E. Fieberg 12. Exploring London through the World of Art and Chemistry: The Properties and Uses of Metals in Sculpture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 Lynn M. Bradley and Elizabeth Mackie Interdisciplinary or Multiple Levels 13. Dry Laboratory Forgery Investigation of a Purported Giorgio de Chirico Painting for a “Chemistry in Art” Course . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 Jeffrey E. Fieberg and Gregory D. Smith 14. Teaching Undergraduate Chemistry through Fibers and Dyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357 Angela G. King and Annelise H. Gorensek-Benitez 15. Integrating Archaeology and Interdisciplinary Collaborations with Museums into the Chemistry Curriculum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381 Kevin L. Braun 16. An Introduction to Ceramic Glaze Color Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403 Jennifer L. Wicks and Ryan H. Coppage 17. The Heterogeneity Problem: Intermolecular Forces as They Relate to Solubility and Chromatography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425 Joseph F. Lomax and Suzanne Q. Lomax Editors’ Biographies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
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Indexes Author Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 463
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Preface–Chemistry’s Diverse Applications in Art and Archaeology Over the last thirty years, numerous initiatives have been made to improve chemistry education. These calls for reform often ask educators to adopt pedagogies that actively engage students in the learning process, promote student agency, and demonstrate chemistry’s broad applicability while still conveying core chemical concepts. Teaching chemistry in context provides a vehicle to meet these challenges while also building enthusiasm for the field for chemistry majors and nonmajors. Common themes that have proven effective at improving student learning outcomes include forensics, food, and the environment. Art and archaeology, situated at the intersection of the humanities and the sciences, can similarly provide rich contexts to not only engage students in the study of chemistry but also provide a unique platform to promote cultural literacy and demonstrate chemistry’s crosscutting application. From assisting in the study of humanity’s past to the preservation of priceless works of art, chemistry provides critical techniques and instrumental methods used in the fields of art and archaeology. This book highlights the interdisciplinary interface of chemistry, art, and archaeology and provides instructors with robust art and archaeology centered activities, course plans, case studies, study-abroad experiences, and laboratories that can enhance the chemistry curriculum by making key chemical concepts more relatable and accessible. Chapters in this book include detailed descriptions from experts of the implementation of these curricular materials with the aim of inspiring other chemistry instructors to adapt and expand these ideas within their own classrooms.
Chemistry’s Role in Art and Archaeology Chemistry plays a key role in the fields of art and archaeology by providing not only understanding of structure and function relationships, but also chemical and instrumental methods necessary for characterization. Within art, pigment analysis by X-ray fluorescence (XRF) spectroscopy can identify likely pigments or provide evidence of pigment decomposition. Imaging techniques, including photography using X-ray, near IR, or UV radiation sources, or more advanced multispectral and hyperspectral reflectance imaging spectrometries, can reveal information about compositions beneath the top layer. Microscopy of cross-section samples of paintings can inform construction of a painting’s layers. These analyses provide information about the composition of a painting and can be used to address questions of authenticity or can be used to plan conservation or restoration efforts. Within archaeology, chemical methods and instrumentation have proved critical to the dating, characterization, and authentication of material remains for over two hundred years. From the application of early quantitative analysis methods by Martin Heinrich Klaproth to Greek and Roman coins to Willard Libby’s “radiocarbon revolution,” a diverse range of chemical methods found application within archaeology’s early multidisciplinary approach. Chemistry’s early relationship with archaeology has evolved and expanded over the last fifty years with the development
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of archaeological laboratories dedicated to chemical analysis. This has led to significant growth in archaeology’s sub-disciplines of archaeometry and archaeological chemistry. We use the terms “art” and “archeology” to broadly encompass all areas of the examination of the materiality of objects of value, including creative works, historical artifacts, ethnographic assemblages, and more. Some may refer to these as “cultural heritage objects”. This discussion of terminology reflects the interdisciplinary nature of this work, and reflects that work in this area, rather than being collaborative (e.g., an artist hands a sample to a scientist for analysis), has truly moved into the interdisciplinary. Contemporary museum curators, conservators, and conservation scientists are expected to have knowledge in multiple areas, including fine arts (artists materials and techniques), history (art history and anthropology), and science (chemistry, physics, etc.). Today, museums house chemistry laboratories with state-of-the-art instrumentation rather than contracting this work to outside labs. This richly interdisciplinary model lends “art” and “archaeology,” terms that students may be most familiar with, to serve as inviting vehicles to teach key chemical concepts, as chemical concepts are embedded into numerous aspects of this work. These stories fit anywhere into the chemistry curriculum, from introductory to the advanced courses. Furthermore, these topics are suitable for both majors and nonmajors, and are especially valuable for students hoping to enter careers in the areas of art conservation and archaeology as these traditionally “non-STEM” graduate programs are requiring additional chemistry courses (another indication of our aforementioned shift from the collaborative to truly interdisciplinary model).
Teaching Chemistry in Context Despite being considered “the central science,” instructors often encounter students with limited impetus or interest in the study of chemistry. This reality is exacerbated by the fact that the majority of students taking chemistry courses are not majors and only seeking the credit(s) to fulfill prerequisites for STEM majors or as a distribution requirement. Pedagogically, traditional teaching methods that rely on lecture-based delivery modes and rote memorization further fuel students’ indifference and lack of engagement with the field (1). Traditional lecture-based methods also fail to engage students in meaningful learning and advance the development of high-order critical thinking and problem-solving skills (1–4). Context-based teaching provides a means to overcome these obstacles and foster enthusiasm within the chemistry classroom (5–8). As characterized by Stacy Bretz, for meaningful learning to occur a curriculum must engage students’ prior knowledge, include materials that connect with students’ prior knowledge, and provide space for students to connect their prior knowledge with new knowledge and ways of thinking (1). Context-based methods, which center their pedagogy within a relatable context(s) or societally pertinent question(s) to students’ lives, creates an ideal platform to ignite student interest and motivation thus fostering an environment suitable for meaningful learning to occur (7). It should be noted that the successful implementation of a context-based pedagogy requires a critical evaluation of the curriculum’s goals and modes of evaluation (7, 9). When thoughtfully constructed, context-based methods have been shown to improve persistence, reduce failure rates, and create student knowledge that can be transferred to new applications (2, 3, 6, 7). Successful models for context-based learning can be found based on forensics (10), food (11), and the environment (12–14).
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Bringing Art and Archaeology into the Chemistry Classroom There are many examples of chemistry concepts that can be taught in the context of art and archaeology. Students are excited to learn about atomic spectroscopy and the intricacies of electron transitions when it is in the context of XRF analysis of paintings. There is chemistry behind the recipe formulations for dyeing fibers, considering dye source, concentration, mordant, pH, and more. Ceramics glazes provide a colorful platform to discuss crystal field theory of pigment structure, and spectral analysis of color out puts. Furthermore, these applications allow for possible collaborations with artists, art instructors, art historians, or museum staff. This models for students the interdisciplinary nature of this work, and allows faculty to build cross-campus or community relationships. Reconstructing the complex tapestry of human development through the analysis of material remains and reconstruction of ancient chemical technology naturally requires a diverse range of methods and instrumental methods. Since chemistry provides many of these key techniques and instruments, archaeology provides a content-rich platform to derive course materials from the introductory to advanced level. As presented within this book, this can take the form of visual artifact analysis for material properties, the synthesis and characterization of historic pigments and dyes, the use of case-studies derived from the research literature, the analysis of replicate artifacts, and the characterization of authentic artifacts through collaboration with museum curators and archaeologists. Replicate artifacts facilitate student engagement in answering archaeological themed questions without the need for direct access to priceless and irreplaceable artifacts or a museum. Through collaboration with local archaeologists or museum curators, the analysis of authentic artifacts may be possible especially if non-destructive methods are applied and ethical concerns are taken into consideration. Finally, woven within many of these archaeological applications is the need for elemental and molecular characterization, which provides ample opportunity to integrate instrumentation throughout the curriculum. Context-based teaching through art and archaeology provides a unique platform for instructors to integrate cultural literacy with in the chemistry curriculum. Both destructive and non-destructive chemical analyses of works of art, archaeological artifacts, and other cultural heritage objects come with broader ethical considerations regarding the history and ownership of the object. These considerations require thoughtfulness of the instructor and consultation with curators, museum staff, and/or object owners regarding appropriate use and handling. These considerations are important to bring into the classroom as well, to train science students to be aware and respectful towards the creators of cultural heritage objects, taking care not to exploit them for personal or professional benefit. Activities derived from art and archaeology allow students to see chemistry’s crosscutting nature and can engage them in authentic applications of key theories, synthetic techniques, and instrumental methods. When combined with collaborations, through local museums for example, these contexts also facilitate learning outside the traditional laboratory further demonstrating chemistry’s broad applicability.
Acknowledgement of Inspiration This book arose from the symposium Chemistry Connections in Art and Archaeology, which was organized for the 2020 Biennial Conference on Chemical Education (BCCE). The symposium’s goal was to bring together instructors exploring art and archaeology as vehicles to actively engage students in the study of chemistry. Although the symposium and conference were canceled due to the global xiii
pandemic, the diverse collection of talks demonstrated the unique ways these topics could be applied to the teaching of chemistry from the introductory to the advanced level. As symposium organizers turned book editors, while we have been connecting chemistry to art and archaeology within our own classrooms for several years, we gratefully acknowledge that our interest in the field was inspired by those who pioneered work in these areas. Since 1933, the Journal of Chemical Education has regularly highlighted chemistry’s key role in the field of archaeology (15–21). Chemistry’s role in the qualitative and quantitative analysis of antiquities stretches back even further, over two hundred years, and is well documented (22–25). Starting in 1950 and continuing to this day, the ACS Division of History of Chemistry has hosted a subdivision of Archaeological Chemistry which has hosted prolific symposia and several volumes of ASC Symposium Series books (26). Additionally, in The Journal of Chemical Education, articles related to courses in the chemistry of art appear as early as 1971, and the theme of two issues of the journal, one in 1980 and one in 1981, was “The Chemistry of Art” (27–29), featuring several articles by Sister Mary Virginia Orna, another pioneer in this area. Her work lies at the intersection of chemistry with both art and archaeology; her numerous publications in these areas are foundational and span from journal articles, to textbooks, to multiple volumes of ACS Symposium Series Books (30, 31). Specifically, we were each inspired to teach in context after our own participation in and hosting of workshops sponsored by the phenomenal NSF-supported Chemistry Coalitions, Workshops, and Communities of Scholars (cCWCS) program (TUES Type 3 Project #1022895, Jerry Smith of Georgia State University, David Collard of Georgia Institute of Technology, Patricia Hill of Millersville University, and Lawrence Kaplan of Williams College). This project supported dozens of workshops from 2011 to 2017 in a variety of areas of chemistry (e.g. renewable energy, nanochemistry, medicinal chemistry, chemistry in art) for hundreds of participants and also supported outreach activities, topical community websites, and presentation of workshop-inspired ideas and curriculum at national conferences (especially the American Chemical Society and the Biennial Conference on Chemical Education). A full description of the robust history of these workshops and this community of scholars is described in a book chapter by Patricia Hill and Deberah Simon (Whitman College), who facilitated several cCWCS workshops in the area of chemistry and art (32). Briefly, the predecessor of cCWCS was a similarly titled program, Center for Workshops in the Chemical Sciences (CWCS), led by Jerry Smith, Lawrence Kaplan, David Collard, and Emeliata Breyer and running from 2000-2011 (NSF-DUE-CCLI #0089417, 0341138, and 0618678). Prior to these workshops Pat Hill and Michael Henchman (Brandeis University) were running short courses for other chemistry instructors detailing their independently developed chemistry in art courses for non-majors. These initial workshops played a key role in the CWCS and cCWCS workshops. This book builds upon the rich foundation set from these workshops as many of the authors here were indeed workshop participants (or co-facilitators). This book provides detailed descriptions of how chemistry instructors have incorporated these materials into their own classroom. Many of these chapters describe curricula that have been implemented several times and benefit from multiple cycles of testing and refining. The goal is to provide detailed, robust resources that make it easy for instructors to adapt to their own classrooms, thereby benefiting students and successfully teaching chemistry concepts.
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Chapter Organization Within this book, each chapter will include: 1- Learning goals and/or objectives for the course or activity described. Skills that students practice and chemistry concepts taught within the course or activity will also be stated. 2- Details regarding the students for which course or activity has been implemented. This includes information on the level (high school, introductory, advanced), as well as a more specific description of background knowledge required for students to meaningfully engage with the material. 3- Feedback and assessment information, when available, describing how successful the course or activity has been at achieving the set learning goals. This may entail a description of successful student engagement from the instructor’s viewpoint, a summary of assessment scores, student-reported learning gain assessment responses, or student quotes. Chapters in this book are grouped together by similarities, though it is hard to provide welldefined categories as many chapters cover multiple topics or teaching levels. Chapters that include applications that are suitable for non-majors include Chapters 1-6, 8, and 11-17. Applications of advanced chemical instrumentation are included in chapters 7-10, 13, 15, and 17. Entire course curricula and modules are presented in chapters 1-7, 11-12, and 14. Two chapters describe specific, advanced topics thoroughly and may be useful references for chemistry instructors; chapter 9 describes thorough background of multispectral and hyperspectral reflectance imaging spectroscopy and provides sample data sets upon request, while chapter 16 includes valuable accounts of the chemistry behind ceramics glaze colors. Content and data-rich case studies are presented in chapters 9, 10, 11, and 13. Chapters that describe student interaction with museum collections include 1, 7, 8, 11-12, and 15.
Conclusion We hope this book continues to achieve the original goals for this community of scholars, as described by Hill and Simon: “to bring forth transformative education to undergraduates and engage students and faculty in authentic research with service to those whose profession is to understand, protect and preserve cultural heritage objects” (32). In the spirit of community, the authors of these chapters are passionate about effective chemistry education and are very willing to share additional resources and answer questions about their chapters with readers keen on implementing these ideas into their own classrooms.
Acknowledgments We would like to thank the chapter authors who were a delight to work with. Each author conveys clear passion for their work and expertise in these areas. Additionally, we acknowledge that authors worked on this project during a pandemic when they were no doubt juggling many responsibilities in addition to teaching, yet still carved out time to write and revise their manuscripts. We appreciate the support and encouragement of the ACS Books Editorial Office, especially Amanda Koenig and Alison Kreckmann and the outstanding staff at Technica Editorial Services,
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including Katrina Mulally, Kayci Wyatt, and Tracey Glazener. Their steadfast guidance and encouragement made this book possible.
References 1. 2.
3. 4.
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6.
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Bretz, S. L. Novak’s Theory of Education: Human Constructivism and Meaningful Learning. J. Chem. Educ. 2001, 78, 1107–1116. Overton, T. L.; Byers, B.; Seery, M. K. Context- and Problem-Based Learning in Higher Level Chemistry Education. In Innovative Methods of Teaching and Learning Chemistry in Higher Education; Eilks, I. B. , Ed.; Royal Society of Chemistry, 2009; pp 45–61. Ültay, N.; Çalık, M. A Thematic Review of Studies into the Effectiveness of Context-Based Chemistry Curricula. J. Sci. Educ. Technol. 2012, 21 (6), 686–701. National Research Council (U.S.). Discipline-Based Education Research: Understanding and Improving Learning in Undergraduate Science and Engineering; Singer, S. R., Nielsen, N., Schweingruber, H. A., Eds.; The National Academies Press: Washington, DC, 2012. Mahaffy, P. G.; Holme, T. A.; Martin-Visscher, L.; Martin, B. E.; Versprille, A.; Kirchhoff, M.; McKenzie, L.; Towns, M. Beyond “Inert” Ideas to Teaching General Chemistry from Rich Contexts: Visualizing the Chemistry of Climate Change (VC3). J. Chem. Educ. 2017, 94 (8), 1027–1035. Nentwig, P. M.; Demuth, R.; Parchmann, I.; Ralle, B.; Gräsel, C. Chemie Im Kontext: Situating Learning in Relevant Contexts While Systematically Developing Basic Chemical Concepts. J. Chem. Educ. 2007, 84 (9), 1439. Parchmann, I.; Broman, K.; Busker, M.; Rudnik, J. Context-Based Teaching and Learning on School and University Level. In Chemistry Education; John Wiley & Sons, Ltd, 2015; pp 259–278. Testa, S. M. On Utilizing Forensic Science to Motivate Students in a First-Semester General Chemistry Laboratory. In Teaching Chemistry with Forensic Science; ACS Symposium Series; American Chemical Society, 2019; Vol. 1324, pp 93–108. Gilbert, J. K. On the Nature of “Context” in Chemical Education. International Journal of Science Education 2006, 28 (9), 957–976. Teaching Chemistry with Forensics Science; Harper-Leatherman, A. S., Huang, L. , Eds.; American Chemical Society: Washington, DC, 2019; Vol. 1324. Using Food to Stimulate Interest in the Chemistry Classroom; Symcox, K., Ed.; American Chemical Society: Washington, DC, 2013; Vol. 1130. Environmental Research Literacy: Classroom, Laboratory, and Beyond; Welch, L. A., Berger, M., Roberts-Kirchhoff, E. S. , Eds.; American Chemical Society: Washington, DC, 2020; Vol. 1351. Climate Change Literacy and Education: The Science and Perspectives from the Global Stage Volume 1; Peterman, K., Foy, G. P., Cordes, M. R., Eds.; American Chemical Society: Washington, DC, 2017; Vol. 1247. Climate Change Literacy and Education: Social Justice, Energy, Economics, and the Paris Agreement Volume 2; Peterman, K. E., Foy, G. P., Cordes, M. R., Eds.; American Chemical Society: Washington, DC, 2017; Vol. 1254. Foster, W. Chemistry and Grecian Archaeology. J. Chem. Educ. 1933, 10 (5), 270–277. xvi
16. Foster, W. Further Applications of Chemistry to Archaeology. J. Chem. Educ. 1935, 12 (12), 577–579. 17. Rowe, M. W. Archaeological Dating. J. Chem. Educ. 1986, 63 (1), 16–20. 18. Beilby, A. L. Art, Archaeology, and Analytical Chemistry: A Synthesis of the Liberal Arts. J. Chem. Educ. 1992, 69 (6), 437–439. 19. Allen, R. O. Cracked Pot Chemistry: The Role of Analytical Chemistry in Archaeology. J. Chem. Educ. 1985, 62 (1), 37–41. 20. Orna, M. V. Doing Chemistry at the Art/Archaeology Interface: 1996 Norris Award Address. J. Chem. Educ. 1997, 74 (4), 373–376. 21. Lambert, J. B. Archaeological Chemistry. J. Chem. Educ. 1983, 60 (4), 345–347. 22. Pollard, A. M.; Batt, C. M.; Stern, B.; Young, S. M. M. Analytical Chemistry in Archaeology; Cambridge Manuals in Archaeology; Cambridge University Press, 2007. 23. Archaeological Chemistry as a Multidisciplinary Field; Orna, M. V., Rasmussen, S. C., Eds.; Cambridge Scholars Publishing: Newcastle upon Tyne, UK, 2020. 24. Pollard, A. M.; Heron, C. Archaeological Chemistry; Royal Society of Chemistry: Cambridge, UK, 2008. 25. Tite, M. S. Archaeological Science–Past Achievements and Future Prospects. Archaeometry 1991, 33 (2), 139–151. 26. ACS Division of the History of Chemistry: Subdivision of Archaeological Chemistry; http://acshist. scs.illinois.edu/arch/index.php (accessed April 21, 2021). 27. Ogren, P. J.; Bunge, D. L. An Interdisciplinary Course in Art and Chemistry. J. Chem. Educ. 1971, 48 (10), 681. 28. The Chemistry of Art. J. Chem. Educ. 1980, 57, 255–282. 29. The Chemistry of Art–A Sequel. J. Chem. Educ. 1981, 58, 290–330. 30. Orna, M. V.; Goodstein, M. P. Chemistry and Artists’ Colors, 2nd ed.; ChemSource, Inc.: New Rochelle, NY, 1998. 31. Orna, M. V. The Chemical History of Color; Rasmussen, S., Ed.; Springer, 2013. 32. Hill, P.; Simon, D. Developing a Community of Science and Art Scholars. In Collaborative Endeavors in the Chemical Analysis of Art and Cultural Heritage Materials; ACS Symposium Series; American Chemical Society: Washington, DC, 2012; pp 219–229. Kristin Jansen Labby, Assistant Professor Department of Chemistry Beloit College 700 College Street Beloit, Wisconsin 53511, United States Kevin L. Braun, Assistant Professor Department of Chemistry Virginia Military Institute 401 Maury-Brooke Hall Lexington, Virginia 24450, United States
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General Chemistry
Chapter 1
Incorporating Conservation Science into the General Education Curriculum Joan M. Esson* Department of Chemistry, Otterbein University, Westerville, Ohio 43081, United States *Email: [email protected].
Researching objects and materials that are important in cultural heritage is one way to engage students studying chemistry. This chapter demonstrates how sabbatical research in conservation science was modified for inclusion in a general education Chemistry in Art course. Hands-on examples of four main roles of a conservation scientist were woven throughout a non-majors class as a framework, and the activities served as engaging vehicles to teach chemical principles. The roles include conducting research to aid in art historical analysis; curating exhibits; completing fundamental scientific research to better understand materials used in art; and most importantly, supporting conservators to aid in conservation efforts.
Introduction In Spring 2019, I was a Project MUSE fellow at the Indianapolis Museum of Art (IMA) at Newfields (MUSE - MUseum Sabbatical Experience for Faculty Teaching at the Arts-Science Interface). During my first exposure to conservation science in a museum setting, I learned about four main roles of conservation scientists and completed projects that addressed several of these. When I returned to Otterbein University, I had the opportunity to teach a general education Chemistry in Art course in Summer and Fall 2020. In this chapter, I will briefly describe my work at the IMA and how I adapted the four roles of a conservation scientist into the curriculum (Scheme 1).
Conservation Science in Sabbatical Studies Conservation scientists serve four main roles – first, conducting research to aid in art historical analysis; second, curating exhibits; third, completing fundamental scientific research to better understand materials used in art; fourth and most importantly, supporting conservators to aid in conservation efforts. While at the IMA, I worked on three projects that informed curricular developments at my home institution: multi-analytical method studies of (i) purportedly the oldest surviving Persian knotted-pile silk carpet, (ii) a Japanese yukata, and (iii) the colorant in the Central American dyestuff Justicia spicigera. © 2021 American Chemical Society
Scheme 1. Graphic Illustrating Four Main Roles of a Conservation Scientist (Left), the Experiences Gained Before or During My Sabbatical (Middle), and the Projects Introduced into the Curriculum (Right)
Role 1: Conducting Research to Aid in Art Historical Analysis The Cleveland Museum of Art (CMA) acquired a textile fragment (1988.243) in 1988 that was believed to be the earliest example of a Persian silk knotted-pile carpet, possibly dating from the 15th century based on stylistic grounds. However, there were questions about its authenticity, due in part to the fact that its provenance dates back only to 1928. Rather than conducting carbon-14 dating, which requires a large sample of undyed yarn that could compromise the stability of the carpet fragment, the CMA textile conservator requested that dye analysis be completed, which uses less than 1 mg of a pile knot. Although the identification of only natural dyes could not exclude the possibility that the carpet was a modern creation, the presence of synthetic dyes could establish the date it was made. X-ray fluorescence (XRF) was used to identify mordants, while Raman spectroscopy and liquid chromatography-photodiode array detector-mass spectrometry (LC-DADMS) was used to identify the dyes. Several modern colorants were found, including Metanil yellow, Congo red and indigo, which may have been from a synthetic source. Given that the history of the carpet fragment could only be traced back to 1928 and that these dyes were introduced between 1879 and 1897, the conclusion is that the textile is a late 19th or early 20th century creation (1). My sabbatical examination of the Persian silk knotted-pile carpet led me to consider how handson studies of authenticity can be incorporated into the curriculum. The question of authenticity appeals to students, as evidenced by examples of fakes and forgeries incorporated into general education or chemistry courses (2–4). I was especially interested in developing a hands-on project that includes materials that have not yet made their way into the undergraduate curriculum, at least to the best of my knowledge. These include materials like textiles and illuminated manuscripts. 4
Role 2: Curating Exhibits In 2017, the IMA held an exhibition, Chemistry of Color, which is part of their CSI (Conservation Science Indianapolis) series that focuses on how science informs the study of art. In preparation for this exhibit, conservation scientists at the IMA studied several blue Japanese yukatas (traditional Japanese summer garments that resemble kimonos) for use as examples of objects with the blue dye indigo. Unexpectedly, the dye was found not to be indigo but the synthetic 5-5′-dibromoindigo, which had not been previously found in a museum context (5). During my sabbatical in 2019, I completed a follow-up analysis of another yukata (2016.46) using XRF, Raman spectroscopy and LC-DAD-MS and found the same synthetic dye. The idea of a Chemistry of Color exhibition could be adapted for use at the undergraduate level and is well-suited to a general education Chemistry in Art course that studies the structure and characteristics of pigments and dyes. Role 3: Fundamental Scientific Research The plant Justicia spicigera, which is native to Central America and Mexico, is a pre-Hispanic dyestuff first documented in the 16th century (6–8). Despite its use as a dyestuff for over 500 years, the structure of the colorant had yet to be identified when I started my sabbatical. It was originally thought to be indigo, but subsequent studies had shown that is not the case, and, instead, some researchers believe it to be an anthocyanin (9, 10). Using multiple methods, my sabbatical research showed that the colorant was not an anthocyanin but rather a phenoxazine, a class of compounds found in other materials, such as litmus, purple orchil dyes and the Asian plant Peristrophe bivalvis, which is used as a source of purple or magenta food dye, particularly in Vietnam (11, 12). Although I dyed textiles with Justicia spicigera as part of my sabbatical work, a systematic study of its dyeing properties had yet to be done. Such studies could be added to a textile and dye unit in a general education Chemistry in Art course.
Role 4: Supporting Conservators Conservation scientists also support conservators when consulting on chemical structures and behaviors that inform conservation and restoration efforts. The project described earlier to identify materials in the Persian silk knotted-pile carpet is an example of work to support conservators. Beyond studies done at the IMA, I previously developed an activity that mimicked research done to support conservators that was grounded in a real-world scenario (13). In 2012, the Mark Rothko painting Black on Maroon, while hanging in the Tate Modern gallery, was vandalized leaving graffiti ink. This event was the inspiration for developing of an activity that modeled what conservators and conservations scientists did. The students create test samples of paint covered with the same ink used in the graffiti and study various solvents to determine the best one to remove the ink, taking advantage of their knowledge of the principle “like dissolves like.” Although this activity was previously used in our general chemistry laboratory, it could be adapted to a Chemistry in Art course to illustrate this aspect of conservation science.
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Incorporating Conservation Science Principles into a General Education Chemistry in Art Course Since the 1970s, courses relating chemistry and art have been used to teach nonscience majors (14, 15). Although I have drawn on previously published materials to develop my course, I hope to add to this conversation by sharing what is likely a new framework, as well as new hands-on activities that were inspired by my sabbatical research as described above. Although my course does not have an associated laboratory, the class meetings alternate between “lecture” and “laboratory” settings, providing time for students to experiment with materials and methods used by conservation scientists. The four roles of a conservation scientist were woven throughout a new general education course on Chemistry and Art, as shown in Table 1. Although not all modules and activities for the course are shown, this table emphasizes the modules that include a hands-on activity that introduces the role of a conservation scientist. Table 1. Partial Structure of the Chemistry in Art General Education Course with Emphasis on Newly Developed Activities That Illustrate the Roles of a Conservation Scientist Teaching Module
Activity
Role
Colorants
“Chemistry of Color” exhibition
2 (Curating an exhibit)
Paintings
Removal of graffiti ink
4 (Supporting conservators)
Analytical Tools
Authenticity of cultural heritage objects
1 (Art historical analysis) and 4 (supporting conservators)
Photography
Anthotypes from natural sources
3 (Fundamental research)
Textiles and Dyes
Dyeing with a Central American dyestuff 3 (Fundamental research)
Curating an Exhibit (Role 2) The first module in the course involves an exploration of colorants: – from pre-historic to ancient to modern. In the process, several basic chemistry topics are introduced, such as atomic structure, ionic compounds, covalent compounds, precipitation and oxidation-reduction chemical reactions, and isotopic behaviors. For this last topic, I incorporated a discussion around the use of lead isotopes, particularly to identify the geographical origin of lead white in Vermeer’s Saint Praxedis, the attribution of which was in dispute prior to a Christie’s auction in 2014 (16, 17). This brings up the question of authenticity early in the course and can be used as an example of the role of conservation science. Using experiments from several excellent publications, the hands-on portion of this colorant module involves synthesizing or isolating different colorants that are used in later weeks to create paints, paintings and frescoes (18–22). This module also includes a mini-research assignment in which students investigate one ancient and one modern pigment. The students are asked to: • • • •
Identify if each colorant is organic or inorganic, covalent or ionic, natural or synthetic. Provide information about its history. If natural, describe when it was first discovered. If synthetic, describe how it is made and when it was first created. 6
• Provide the chemical formula and (if a dye) the chemical structure. • Identify at least one object that contains the colorant. • Prepare the information in an engaging, informative way for their classmates and outside audience. Initial sources that are recommended to the students include Pigments through the Ages (http://www.webexhibits.org/pigments/), Colourlex: Paintings, Pigments, Resources (https://colourlex.com/), and CAMEO (the Conservation and Art Materials Encyclopedia Online, http://cameo.mfa.org/wiki/Main_Page). A video is also shown, which highlights the Chemistry of Color exhibition at the Indianapolis Museum of Art at Newfields (23). If the course is taught online, a virtual Chemistry of Color exhibition can be created (in Otterbein’s case, the university has access to a Digication ePortfolio platform). This allows students to showcase each ancient and modern colorants’ chemistry along with at least one object that illustrates its use. As part of the virtual exhibition, students gave brief presentations about their findings. Because of the outward-facing nature of the assignment, the students seemed to put additional effort into it. They were graded on how well they met each of the learning goals in the bulleted list above on a three-point scale (poor, met, exceeded), and the majority met or exceeded these criteria. This indicates a strong ability to make connections between colorants and the underlying chemical topics. Once we return to a more regular schedule post-COVID, my students and I will work with Otterbein’s Museum and Galleries Director to design a physical exhibition within one of our STEM buildings. The advantage to completing a virtual exhibit is that it is relatively easy to find an artwork or other cultural heritage object containing a specific colorant. Moving to a physical exhibition will require students to investigate our limited university collection or else include a photograph of an object. Supporting Conservators (Role 4) In the second module on paintings, students explore the concepts of intermolecular forces and the mnemonic of “like dissolves like,” among other ideas. They complete the hands-on activity mentioned earlier, in which students determine the best solvents to remove graffiti ink from a test sample that models the Mark Rothko Black on Maroon vandalism (13). This provides an opportunity for students to learn how conservation scientists aid conservators. In addition to material described in the publication, students also learn about and use Teas solubility diagrams (24). The students are graded on their ability to: • Successfully create paint samples that incorporate different binders • Identify the relative polarity of the graffiti ink • Choose appropriate solvents based on the polarity of the ink and solvent, as well as that of the binder and colorant • Successfully remove the graffiti ink • Document their experiment and explain their results using the concept “like dissolves like” along with Teas solubility diagrams Some students in the Chemistry in Art course struggle with choosing solvents and explaining their choice. To help them, we review the structures of solvents and binders as a class and talk about the relative polarities of these in relation to the relatively non-polar graffiti ink. They then choose their 7
approach after this discussion. The majority at least met the above criteria. However, few students incorporated a sufficiently detailed discussion relating the structure of a chemical to its position on a Teas solubility diagram, and what specific intermolecular forces would be important between the solvent and ink or solvent and binder. To reinforce and check their ability to identify proper solvents for treatment based on chemical structures and Teas solubility diagrams, students also watch a video in which a paintings conservator from the National Gallery describes and demonstrates her work on a particular painting, The Horse Fair (25). The varnish is described as a synthetic, waxy substance, and a solvent mixture is used to clean the painting. However, the solvent is not specified. Students are asked to speculate on what solvents might be used and support their decision. With this second application of chemistry concepts, the majority of students are now able to use Teas solubility diagrams, such as those in (24), to choose an appropriate solvent and explain similarities in chemical structures of the varnish and solvent to discuss the principle “like dissolves like.” We also briefly discuss other cases in which spray paint or ink has been used to vandalize artworks, such as Pablo Picasso’s Woman in a Red Armchair and Anish Kapoor’s Dirty Corner. General education courses within Otterbein’s Integrative Studies program must all consider the overall program theme of “Knowledge, Action and the Public Good.” Discussion of the importance of these works to cultural heritage and questions about the need for conservation provides an integral connection to this theme. Finally, students also consider case studies I created from Personal Viewpoints: Thoughts About Paintings Conservation (26). In this publication, a group of distinguished conservators discuss a treatment they completed in the past, reflect on how they approached their work, and identify what, if anything, they might do differently if they were to do the conservation today. Incorporating this discussion further ties to the general education theme of “Knowledge, Action and the Public Good.” Students reflect on different variables a conservator must consider during a conservation treatment, how those considerations may change over time, and how conservation and conservation science serve a public good. Conducting Art Historical Analysis – Search for Authenticity (Role 1) Some excellent experiments have been developed for undergraduate or master’s programs that analyze museum or archaeological objects (27–31). However, adapting these projects to other academic institutions requires a collaboration with a museum or other professionals that some universities may not have. To avoid this requirement or minimize the pressure of a high-stakes assignment of analyzing a cultural heritage object, some experiments use simulated or found objects in lieu of museum pieces (2, 3, 32–34). A few of these activities incorporate the concept of authenticity by asking students to identify if an archeological or simulated object, such as paintings, gemstones or coins, is a forgery (2–4, 27). The experiment described here expands on the available activities and introduces the analysis of illuminated manuscripts and textiles, which have not received much attention in the undergraduate curriculum. In this activity, several illuminated manuscript pages and textile fragments purportedly as old as the 13th century were purchased from eBay. Students are given the information provided by the seller about the origin and age of the object and tasked with conducting chemical analyses to see if the materials in the object are consistent with this information. This framework of authentication of real-world objects engages students while showcasing Role 1.
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In the current Chemistry in Art course, students use Raman spectroscopy to examine only the illuminated manuscript pages. Given the class size (24 students), limited class meeting time (one hour), and available instrumentation, Raman spectroscopy is used since spectra could be collected quickly without the need for sample preparation. However, depending on the emphasis of the course in the future, additional analytical tools and objects, such as textiles, could be included. Raman spectroscopy has been used to identify pigments in manuscripts and the presence of anachronistic colorants used to identify modern forgeries of supposedly aged manuscripts, including Egyptian papyri, medieval miniatures, the Vinland map, and Arabic illuminated manuscripts (35–37). The last of these pertains most directly to my course since the illuminated manuscript pages purchased from eBay contain Arabic writing. These examples can be used to prepare and excite students for the authentication activity. Before the activity, students are introduced to key themes in Raman spectroscopy: that this technique probes molecular vibrations using light; and that those vibrations have different frequencies associated with them based on atomic mass and bond strength. Additionally, we work through an example using Raman spectra in the Infrared and Raman Users Group (IRUG) spectral database found at irug.org. The synthetic pigment copper phthalocyanine was found in a supposedly 14th century Arabic illuminated manuscript, which indicated it was a modern creation since the colorant was not synthesized until the early 20th century (37). We compare the Raman spectrum of copper phthalocyanine in the IRUG database to that of blues that would be expected, such as ultramarine (38). Students are assigned an illuminated manuscript and generate a list of possible dyes or pigments they expect to see based on the purported date of the manuscript, the coloring on the object, and the timeline of pigments and dyes they created during the first module or available at the Pigments through the Ages website. After learning how to use the Raman spectrometer, students collect Raman spectra on different areas of the illuminated manuscript page and compare it to those found in the IRUG database for their possible colorants. As an example, Figure 1 shows an illuminated manuscript page and the Raman spectra from the yellow area of a tiger on the left side and a green area below the animal. The students found that the best match to these spectra in the IRUG database was chrome yellow, which dates the manuscript to the early 19th century or later. The students were graded on: • The correct identification of the colorant based on its Raman spectrum • Justification for their identification of the colorant (discussion of other possible Raman spectra) • Identification of the possible age of the illuminated manuscript • Explanation of the basic idea behind Raman spectroscopy All students met the three-staged grading criteria organized around these bullet points (poor, met, exceeded). They found the pattern matching of Raman spectra between their sample and the database to be relatively straightforward. Students also understood the idea that the mass of an atom and bond strength influences frequencies of vibrations. However, they were not readily able to articulate the relationship of vibrational frequency to the more complex spectra they collected.
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Figure 1. Example of illuminated manuscript page studied (left). Area A is the tiger from which Raman spectrum A was taken (A). Area B is green grass from which Raman spectrum B was taken (B). Raman spectrum A is similar to that expected for chrome yellow. Further, the similarity of Raman spectra A and B suggests that the green color was made from chrome yellow and an unidentified blue colorant. Fundamental Research of Materials in Art and Cultural Heritage (Role 3) The last two projects integrated into the Chemistry in Art course introduce the remaining role conducting fundamental research of materials used in art and cultural heritage objects. Both projects investigate the use of the previously mentioned Central American dyestuff Justicia spicigera, also known as muitle – in one case to create anthotypes and in the other case to create colored textiles. Project 1: Anthotype Plant Prints Although such an activity had not originally been planned in the syllabus for Chemistry in Art, I read the BBC article “Art in lockdown: Making anthotype plant prints” concurrently with offering my course and then decided to add a unit on anthotypes into the photography module (39). Given that colorants from plants were discussed earlier in the course, this seemed like a natural fit. Further, since cyanotypes were already included in the photography module, adding anthotypes also allowed for a comparison of different types of chemistry that can be used to make sun-based prints. Lastly, it provided an opportunity to collaborate with our university’s Community Garden and further explore the behavior of muitle, which had not previously been used for anthotypes. Anthotypes are similar to cyanotypes in terms of how the print is made: an object is placed on prepared paper and placed in the sun. However, the chemistry of the two is quite different. Cyanotypes exploit the relatively fast oxidation-reduction of iron pigments on paper coated with potassium ferricyanide and ferric ammonium citrate when exposed to the sun. On the other hand, anthotypes use paper dyed with organic plant pigments that fade more slowly over several minutes to several days. The colored organic compounds, such as anthocyanins or betalains, in the plant extract absorb UV light, which causes pi bonds to break, decreasing the dye content. To collect materials used to create the anthotype paper, students from Chemistry in Art visited our university’s Community Garden to collect dyestuffs such as beetroot, spinach, pokeweed, 10
calendula, hibiscus, and other flower petals. The Otterbein University Community Garden was established over ten years ago, and produce from the garden supplies food pantries and our Promise House, a resource for students with food insecurity. However, many Otterbein students are still unaware of its existence and/or have never been to it. Thus, not only did visiting the garden provide materials for the course, but this activity also provided an introduction for students to this aspect of campus and a further exploration of our general education theme, “Knowledge, Action and the Public Good.” In addition to materials collected at the Community Garden, students were also provided with muitle leaves purchased from eBay or Etsy. To create the anthotype print, the dyestuff was ground, mashed, or cut into smaller pieces and mixed with water or alcohol. This solution was then painted onto watercolor paper. The students took this paper home, placed objects on top of it, and left it in a window to create the print. All the plant materials could successfully produce an anthotype print, including muitle, which is not too surprising since textiles dyed with Justicia spicigera are known to fade (40). Students documented their project in their Digication ePortfolio pages and were graded based on: • Their description and documentation of the activity • Discussion of the similarities and differences between cyanotypes and anthotypes • Explanation of oxidation-reduction as the basis for color change in cyanotypes and UVinduced cleavage of pi bonds for anthotypes Like the other activities, students were graded on a three-point scale for each of the bulleted learning goals, and most students who completed the assignment at least met the criteria. They were able to correctly describe the different types of chemicals and reaction speeds in each photographic method while commenting on the similarity of a light-induced reaction. Although the majority of students understood that different chemical processes occurred, some struggled with a sufficient explanation of the reactions. Project 2: Dyeing Studies The second research activity studied the effect of different mordants and pH on the color of textiles dyed with Justicia spicigera. Dyeing experiments using different mordants and pH conditions have been described previously for general education courses (41–43). However, these have used well-known dyestuffs, such as marigolds, berries, and onion skins. This activity is different in that it examines a lesser-known dyestuff whose dyeing properties have not been thoroughly examined. Reports of colors produced from dyeing with Justicia spicigera include crimson, blue, purple, grey, and red with mordants such as copper, alum, and tin (6, 40). However, no systematic study has been completed to investigate the colors produced under different conditions. Students in Chemistry in Art were tasked with completing such a study. Individual students developed a research question: for example, a comparison of colors produced with copper versus tin as mordants at the same pH or colors produced with tin at acidic and basic pH. The entire class data was also examined and discussed. This is the second of two hands-on activities students complete in the textile and dyeing module. Students first complete the better-known activity exploring how acid dyes from Kool-Aid® interact with various types of fibers on a fabric test strip containing a mixture of eight different natural and synthetic materials. The students examine the structures of the fibers and Kool-Aid® dyes to explain the results they see in terms of molecular interactions, such as ionic bonding and hydrogen 11
bonding. From this first activity, students become familiar with the structures of the different fibers and interactions important for coloration. So, in the second activity, they extend their knowledge of molecular interactions to consider the effects of mordants and explore acid-base behavior. The colorant in muitle is a phenoxazine, like that in litmus paper. Thus, the acid-base behavior is expected to be similar, as shown in Scheme 2 for a generic phenoxazine core.
Scheme 2. Acid-Base Behavior of Phenoxazines In addition to visual observation under ambient light, students also examine the fabric test strips under UV light and with fiber optic reflectance spectroscopy (FORS) to gather reflectance spectra and CIE L*a*b values. This additional documentation provides another example of how conservation scientists can complete non-destructive analyses to gather information. UV-induced fluorescence has long been used to study cultural heritage objects, for example examining varnish on paintings. In this case, the use of UV light showcases how a simple tool can be used to examine and identify textile dyes. For example, in Figure 2, we see that textiles dyed with muitle are more fluorescent than those dyed with another phenoxazine containing dyestuff, Peristrophe bivalvis. Additionally, students use UV light to examine several provided textiles, such as shawls and scarves, to identify which were likely dyed with muitle. This is akin to how conservation scientists and conservators may first survey a collection before conducting more extensive tests to identify a colorant.
Figure 2. Fabric test strip as it is removed from the muitle dyebath (left). Fabric test strips under ambient light (middle) and 254 nm UV light (right) dyed with Justicia spicigera (top row) or Peristrophe bivalvis (bottom row). The top test strips from left to right are dyed with the following mordant-pH combinations: alum-acid, alum-base, iron-acid, iron-base. The bottom test strips are dyed with alum-acid and alum-base. The identity of the fibers in each test strip from top to bottom are filament acetate, cotton, nylon, polyester, polyacrylic, silk, viscose, and wool. Although FORS and the CIE L*a*b color space have been used to examine materials in cultural heritage objects, limited examples have been published for use in the undergraduate curriculum and are mainly geared toward the analysis of paint (30, 44, 45). The introduction of this activity extends the use of FORS to textiles. Further, its incorporation provides an opportunity for students in Chemistry in Art to look at graphical data. Students examine the combined class data for trends 12
from the a*b plane of the CIE L*a*b color space (Figure 3), for example, identifying shifts in color under different pH conditions and for different dyestuffs.
Figure 3. Color parameters of the wool fibers from Figure 2 projected on the a*b* plane of the CIE L*a*b*color space. Note that fibers dyed under acidic conditions have greater a values (are more red) compared to those dyed under basic conditions. Also, b and a values for fibers mordanted with alum differ between P. bivalvis and J. spicigera, which suggests different phenoxazine molecules are present in each. Students are graded on their ability to: • Develop a suitable research question • Carry out and document the dyeing of a fiber test strip with aqueous muitle or Peristrophe bivalvis extracts • Explain the colors they observe in terms of intermolecular interactions • Examine and document the color of the fabric test strip under UV light, its reflectance spectrum, and CIE L*a*b values • Relate the dominant wavelength observed in the reflectance spectrum to the color seen on the fabric test strip (this draws on earlier discussions about light in the module on analytical tools) • Create a meaningful description and summary in their Digication ePortfolios All students were able to develop a research question, dye their test strip, study it with appropriate tools, and document their findings. However, some students wanted to talk through the molecular interactions occurring in their experiments to be sure they understood the ideas. After these discussions, all students met or exceeded each of the bulleted criteria. Each student was able to explain or draw a representation of the interaction of the fiber with a metal ion and the dye molecule. However, some students struggled to understand the role acidic or basic conditions played on the observed color.
Engagement, Extension and Conclusions The application of chemistry to the conservation of art and cultural heritage objects engaged students in the Chemistry in Art course. At the end of the class, not only did students say that it greatly improved their understanding, but also that it kept them interested, as demonstrated in the following student quotes.
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This was the best [general education] Integrative Studies course I’ve had. I always looked forward to coming to class and really liked how the two disciplines came together. I learn best through doing something so the hands-on activities were great. This was a great course to take and I highly recommend it. We learned some chemistry through art and saw how art conservation serves the public good. The roles of conservation science can also be incorporated into other courses to increase student engagement, such as Analytical Chemistry. For example, the authenticity study of illuminated manuscripts that was used in Chemistry in Art was expanded in Analytical Chemistry. In a miniresearch project, students examine illuminated manuscripts and textiles; research expected materials and methods suitable for their analysis; write a research proposal; and design and carry out their chosen method. This project addresses one of the key learning outcomes for the course – that students are able to choose appropriate methods of analysis, taking into account the advantages and limitations of different techniques. Regardless of which course, the four key roles of a conservation scientist lend themselves well to curricular development and student engagement.
Acknowledgments I greatly appreciate the time I spent learning from conservation scientists and conservators at the Indianapolis Museum of Art at Newfields, most notably Drs. Gregory D. Smith and Victor J. Chen. This was made possible through Project MUSE, which was funded by the generous donation of Dr. and Mrs. John and Sarah Lechleiter. I also want to acknowledge the generosity of Otterbein University to grant my sabbatical and the Faculty Scholarship Development Committee for funding some of this work.
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24. Poliszuk, A.; Ybarra, G. Analysis of Cultural Heritage Materials by Infrared Spectroscopy. In Infrared Spectroscopy: Theory, Developments and Application; Cozzolino, D., Ed.; Nova Science Publishers, 2014. 25. National Gallery. Art Restoration of Rosa Bonheur’s ‘The Horse Fair’; 2018.https://www. youtube.com/watch?v=9L22N8rcYiI&feature=emb_logo 26. Personal Viewpoints: Thoughts About Paintings Conservation: A Seminar Organized by the J. Paul Getty Museum, the Getty Conservation Institute, and the Getty Research Institute at the Getty Center, Los Angeles, June 21–22, 2001; Leonard, M., Ed.; Getty Conservation Institute: Los Angeles, 2003. https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/ personal_viewpoints_vl.pdf 27. Donais, M. K.; Whissel, G.; Dumas, A.; Golden, K. Analyzing Lead Content in Ancient Bronze Coins by Flame Atomic Absorption Spectroscopy: An Archaeometry Laboratory with Nonscience Majors. J. Chem. Educ. 2009, 86 (3), 343–346. 28. Lang, P. L. The Chemistry of Artists’ Pigments: An Immersive Learning Course. Collaborative Endeavors in the Chemical Analysis of Art and Cultural Heritage Materials; ACS Symposium Series;American Chemical Society: Washington, DC, 2012; Vol. 1103, Chapter 14, pp 231–239. 29. Wells, G.; Haaf, M. Investigating Art Objects through Collaborative Student Research Projects in an Undergraduate Chemistry and Art Course. J. Chem. Educ. 2013, 90, 1616–1621. 30. Brasuel, M.; McCarter, A. D.; Bower, N. Forensic Art Analysis Using Novel Reflectance Spectroscopy and Pyrolysis Gas Chromatography - Mass Spectrometry Instrumentation. Chem. Educ. 2009, 14, 150–154. 31. Festa, G.; Saladino, M. L.; Mollica Nardo, V.; Armetta, F.; Renda, V.; Nasillo, G.; Pitozono, R.; Spinella, A.; Borla, M.; Ferraris, E.; Turina, V.; Ponterio, R. C. Identifying the Unknown Content of an Ancient Egyptian Sealed Alabaster Vase from Kha and Merit’s Tomb Using Multiple Techniques and Multicomponent Sample Analysis in an Interdisciplinary Applied Chemistry Course. J. Chem. Educ. 2021, 98, 461–468. 32. Alcantara-Garcia, J.; Ploeger, R. Teaching Polymer Chemistry through Cultural Heritage. J. Chem. Educ. 2018, 95, 1118–1124. 33. Harper, C. S.; MacDonald, F. V.; Braun, K. L. Lipid Residue Analysis of Archaeological Pottery: An Introductory Laboratory Experiment in Archaeological Chemistry. J. Chem. Educ. 2017, 94 (9), 1309–1313. 34. Nivens, D. A.; Padgett, C. W.; Chase, J. M.; Verges, K. J.; Jamieson, D. S. Art, Meet Chemistry; Chemistry, Meet Art: Case studies, current literature, and instrumental methods combined to create a hands-on experience for nonmajors and instrumental analysis students. J. Chem. Educ. 2010, 87 (10), 1089–1093. 35. Clark, R. J. H. The scientific investigation of artwork and archaeological artefacts: Raman microscopy as a structural, analytical and forensic tool. Appl. Phys. A 2007, 89, 833–840. 36. Burgio, L.; Clark, R. J. H.; Hark, R. R. Spectroscopic investigation of modern pigments on purportedly medieval miniatures by the “Spanish Forger”. J. Raman Spectrosc. 2009, 40, 2031–2036. 37. Duran, A.; Franquelo, M. L.; Centeno, M. A.; Espejo, T.; Perez-Rodriguez, J. L. Forgery detection on an Arabic illuminated manuscript by micro-Raman and X-ray fluorescence spectroscopy. J. Raman Spectrosc. 2011, 42, 48–55. 16
38. Knipe, P.; Eremin, K.; Walton, M.; Babini, A.; Rayner, G. Materials and techniques of Islamic manuscripts. Heritage Sci. 2018, 6, 55. 39. Boddy, T. Art in lockdown: Making anthotypes plant prints. BBC; 8 September 2020. https://www.bbc.com/news/in-pictures-53821196 40. Baqueiro-Pena, I.; Guerrero-Beltran, J. A. Uses of Justicia spicigera in medicine and as a source of pigments. Funct. Foods Health Dis. 2014, 4 (9), 401–414. 41. Mihalick, J. E.; Donnelly, K. M. Using Metals to Change the Colors of Natural Dyes. J. Chem. Educ. 2006, 83 (10), 1550–1551. 42. Paixao, M. F.; Pereira, M. M.; Cachapuz, A. F. Bridging the Gap: From traditional silk dyeing chemistry to a secondary-school chemistry project. J. Chem. Educ. 2006, 83 (10), 1546–1549. 43. Tallman, K. A. Introducing Students to Fundamental Chemistry Concepts and Basic Research through a Chemistry of Fashion Course for Nonscience Majors. J. Chem. Educ. 2019, 96, 1906–1913. 44. Hoffman, E. M.; Beussman, D. J. Paint Analysis Using Visible Reflectance Spectroscopy: An undergraduate forensic lab. J. Chem. Educ. 2007, 84 (11), 2007. 45. Sattar, S. Characterizing Color with Reflectance. J. Chem. Educ. 2019, 96, 1124–1128.
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Chapter 2
Archaeological and Historical Pigments: A Unifying Framework for Delivering Relevant Chemical Content Utilizing an Interdisciplinary Approach Christopher R. Vyhnal*,1 and Roxanne Radpour2 1Science Department Chair, Philip Bard Chair for Excellence in Science Teaching,
The Thacher School, Ojai, California 93023, United States 2Andrew W. Mellon Senior Fellow, The Metropolitan Museum of Art, New York, New York 10028, United States *Email: [email protected].
A growing number of chemistry educators at the college level are recognizing the merit in using principles and case studies from archaeology, art history, studio art, and art conservation science to engage their students and improve retention in the study of chemical concepts. We too have witnessed firsthand the advantages of this interdisciplinary approach and have recently designed a number of curricular materials centered on the synthesis and analysis of archaeological and historical pigments as a portion of a second-year, advanced chemistry course that, starting in the fall of 2020, replaced a traditional Advanced Placement Chemistry program at The Thacher School (a private, coeducational, residential high school of 260 students). We present and discuss herein multifaceted learning objectives and curricular materials in five broad yet overlapping content areas: 1) dating of natural pigments in early cave and rock art, 2) pigment synthesis experiments, 3) UV-VisNIR fiber optic spectroscopy measurements for the characterization of pigments and quantification of their colors, 4) fresco painting lime cycle chemical reactions, and 5) usage, as a chemistry instructional tool, of the Cultural Heritage Science Open Source (CHSOS) databases (diffuse UV-Vis-NIR reflectance, Raman scattering, X-ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR)). Utilizing case studies of familiar works of art, primary source archaeometry research papers, focused reading with discussion questions, quantitative problem sets, and traditional laboratory experiments, we demonstrate that significant portions of the content in a traditional high school advanced chemistry course or an introductory college-level general chemistry course can be adapted to this interdisciplinary approach, which utilizes materials of cultural heritage value to present and develop chemical concepts in a manner that is engaging, interesting, aesthetically appealing, and informative for both students and their instructors. © 2021 American Chemical Society
Introduction The study of archaeological and historical pigments yields a wealth of opportunities to explore chemical concepts, archaeological topics, and art historical principles in an intellectually intriguing, visually-stimulating, and interdisciplinary framework. Consideration of pigments’ geographical sourcing, physical purification and refinement, chemical and physical properties, chemical synthesis methods, artistic properties, and historical usage provides an encompassing body of knowledge that ties together diverse academic and professional fields of study, notably chemistry, physics, geology, archaeology, art history, studio art, and art conservation and restoration science. The wide diversity of artistic materials (natural and synthetic, organic and inorganic) used from pre-historic to modern times can facilitate a fascinating educational curriculum featuring a wide breadth of topics to explore for beginning chemistry students at the high school or college level. We demonstrate here how the study of archaeological and historical pigments allows chemistry students to review theoretical principles and practice laboratory, research, and quantitative problem-solving skills while discovering that the work they are doing today in the classroom, laboratory, and library began thousands of years ago in ancient civilizations by individuals who used their empirical mastery of the chemical arts to produce monumental and enduring works of art. The curricular materials described here reflect a portion of the content covered in a new, yearlong, interdisciplinary high school course that was designed to replace a traditional Advanced Placement Chemistry curriculum and instead cover typical inorganic chemistry concepts through a novel lens of their applications in archaeology, art history, studio art, and art conservation science. The goal of this pedagogical shift was to more deeply engage students intellectually by more directly connecting chemistry knowledge, laboratory practices, and analytical skills with their applications in a unifying, humanistic, and intellectually stimulating framework. These new curricular materials are presented here in the hope that other chemistry educators might find them useful and instructive in engaging their students more deeply in the study of chemical principles, thereby enhancing students’ retention of chemical concepts and expanding their view of why the study of chemistry is a meaningful and purposeful enterprise. These classroom activities have been implemented, reviewed, and revised following their use by high school students after two, four-day short-courses offered at the conclusion of the spring terms in 2018 and 2019 (these served as pilot projects designed as “proof-of-concept” tests; see Vyhnal et al., 2020 (1)), and subsequently after the first term of the expanded course was offered in the fall of 2020. A detailed course articulation, complete with a course overview, unit summaries, descriptions of unit assignments and laboratory activities, and a list of utilized web resources and reference text materials was submitted to the University of California’s A-G Course Management Portal and approved in April of 2020. Interested readers may obtain a copy of this course articulation and any of the related curricular materials from the corresponding author. A condensed course outline is provided in Table 1. The unveiling of our new course occurred during the COVID-19 pandemic. Unlike many schools that were forced to close their doors and move to online and remote instruction, we were able to offer the fall term predominantly in the classroom, albeit on a modified schedule, which incorporated an initial two weeks of virtual instruction utilizing two, 50-minute periods per week while students quarantined on our campus. We then transitioned to in-person, masked instruction in a classroom that combined both lecture and chemical laboratory spaces and occurred on a modified block schedule that allotted two, 80-minute periods per week with a third period every seven weeks. The new class was small and included seven high school junior and senior students, all of whom had 20
taken a prior, introductory chemistry course. For group projects and laboratory work the students were placed into three groups of 2-3 students each. The topics described below are presented in the order in which they are introduced in the syllabus for the new course.
Radiometric Age Dating of Cave and Rock Art When did humans first create art and how can we analytically determine this? This is a provocative, complex, and dynamic question. It has us reflect on the essence of what it means to be human: should humanity be defined through genetics, anthropology, or the depth and sophistication of thought as preserved in surviving material culture? It has us consider the nature of art: did the completion of the earliest pictographs on rocks and in caves serve an artistic purpose and fulfill a creative need? And answers to the question change as our understanding of the “earliest” art continuously evolves through additional archaeological, anthropological, and radiometric studies. From a chemistry perspective this topic offers a rich and unique opportunity to engage students and review the chemical concepts of atomic structure, nuclear stability, nuclear decay reactions, and radiogenic isotope systematics in service of a larger goal. In our course we started with an introduction to the oldest known examples of cave art at El Castillo, Spain and Sulawesi, Indonesia using a slideshow presentation, web-based science news articles (2, 3, 4, 5), and assigned discussion questions. We then turned our attention to a case study and problem set on the carbon-14 dating of rock art in the Guadalupe Mountains of New Mexico, USA. The problem set has students review basic concepts of atomic structure: How many protons, neutrons, and electrons are present in a neutral, C-14 atom? To what does the “14” in C-14 refer? What are the other isotopes of carbon? Which carbon isotope is most abundant in nature? What is meant by the term “half-life”? What is the half-life of C-14 and what does this tell us about the oldest objects that can be dated reliably using the method? The problem set prompts students to write nuclear decay reactions for the production of C-14 in the atmosphere by neutron bombardment of N-14 and for the beta decay of C-14. It also requires the students to explain how radiogenic C-14 ages are calibrated against tree rings, speleothems (cave formations), marine corals, and organic samples in dated sedimentary records, and to identify and discuss the various complicating factors in C-14 age determinations. The students were then provided with isotopic data collected from pigment samples with residual organic components that were obtained from similar rock paintings (cervids painted with red ochre) at two different sites separated by about a mile in the same canyon drainage system in the Guadalupe Mountains (Ambush Two Hands sample #4 and Ambush Shelter sample #5, Steelman et al., 2019 (6)) in order to answer the simple question, were they painted at the same time? After using the decay equation to reduce the isotopic data and obtain C-14 ages in years before present, the students converted their calculated ages to calibrated dates using the OxCal web interface (Bronk Ramsey, 2009 (7), OxCal v4.4.2, build #130, IntCal 13 curve), and learned that the rock paintings were separated in time by about 2000 years. The case study clearly and convincingly illustrates for students the usefulness of radiogenic isotope dating in constraining the timing of archaeological events of interest.
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Table 1. Condensed Summary of the Thacher School’s New Course, Advanced Chemistry: Applications in Archaeology & Art (ChemAAA) Examples of activities Chemistry learning & laboratory experiments objectives
Other learning objectives
1) Painting: pigments, binders, surfaces & colorimetric analysis (10 weeks)
• Activity: what is art? • Activity: how do humans see color? • Lab: 14C radiometric dating • Labs: pigment syntheses (madder lake, Prussian Blue, cobalt green, cobalt yellow) • Lab: fiber-optic diffuse reflectance spectroscopy • Multi-week lab: fresco tile
• electromagnetic spectrum & visible light • atomic structure, nuclear chemistry & radiometric dating • balanced equations & stoichiometric calculations • molecular geometry • solubility & precipitation • concentration expressions & calculations • principles of kinetics • oxidation #s & redox reactions
• definitions of art • artistic time periods • biology of the human eye • elements of anthropology • history of usage & artistic properties of pigments • color theory & color spaces • spreadsheet programming • elements of art history
• assigned reading & videos • journal reflections • homework questions • problem sets • lab reports • slideshow & oral presentation • student-created infographic • student-created video • art projects (painting, fresco tile)
2) Pottery & ceramics (4 weeks)
• Activity: archaeology of pottery • Activity: chemistry of pottery • Activity: thermodynamics of redox reactions in Athenian vases • Case study: archaeometry of Via Dei Sepolcri pottery workshop in Pompeii • Multi-week lab: pinch & coil pots
• intermolecular forces • gas law calculations • phase diagrams • specific gravity & refractive index • redox reactions • thermodynamic calculations • methods of scientific analysis (PLM, XRD, XRF, ICPMS, Raman, FTIR, isotopic)
• elements of archaeology & archaeometry • pottery production methods (raw material selection & refinement, shaping, firing, decoration) • Italian geography & geology • ancient Roman trade routes
• assigned reading & videos • journal reflections • homework questions • problem sets • lab report • slideshow & oral presentation • participation during class discussion • art project (pottery pieces)
Unit
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Means of assessment
Table 1. (Continued). Condensed Summary of the Thacher School’s New Course, Advanced Chemistry: Applications in Archaeology & Art (ChemAAA)
Unit
Examples of activities Chemistry learning & laboratory experiments objectives
Other learning objectives
Means of assessment
3) Metallic artifacts (3 weeks)
• Activity: chemical metallurgy • Lab: freezing point of Onion’s fusible alloy • Lab: redox etching a brass medallion • Case study: King Tut’s dagger • Case study: Etruscan gold dental prosthetics • Case study: bronze artifacts of the Qin terracotta army • Case study: XRF of Roman Imperial coins
• chemistry of metal smelting • ternary phase diagrams • freezing point • redox reactions • metal alloy composition & classification • principles of X-ray fluorescence & electron excitation
• elements of archaeology & archaeometry • adaptation of pottery kilns to metal smelting furnaces • metal production methods (raw material selection & refining) • Mediterranean geography • Chinese geography & history • linear regression analysis
• assigned reading & videos • journal reflections • homework questions • problem sets • lab reports • student-created infographic or scientific poster • participation during class discussion • art project (etched brass medallion)
4) Glasses (3 weeks)
• Case study: Malkata & Lisht glassmaking technologies, 2nd century BCE • Case study: Central European glass beads from the Iron Age • Case study: stained glass from the Cathedral of Leon • Lab: making a colored glass bead • Lab: diffuse reflectance spectroscopy of a glass bead
• metals as colorants & opacifiers • XRF, SEM-EDX analysis & data reduction to oxides • stoichiometric calculations & representation of ratios on binary plots • redox reactions • polyatomic ion names & formulas
• Middle Eastern geography • glass production methods (raw material selection & refining, shaping methods) • link between metallurgical & glassmaking processes & vocabulary • linear regression analysis • accurate scientific communication
• assigned reading & videos • journal reflections • homework questions • problem sets • lab reports • student-created infographic or scientific poster • participation during class discussion • art project (colored glass bead)
5) Methods of scientific analysis (2 weeks)
• Field trip: Getty Museum Conservation Institute • Activity: analytical method research
• methods of scientific analysis (XRF, XRD, SEMEDX, FTIR & Raman, UV-VisNIR, photoluminescence imaging)
• none
• assigned reading & videos • journal reflections • student-created video • participation during class discussion
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Table 1. (Continued). Condensed Summary of the Thacher School’s New Course, Advanced Chemistry: Applications in Archaeology & Art (ChemAAA)
Unit
Examples of activities Chemistry learning & laboratory experiments objectives • IR and X-ray imaging methods • solvent chemistry • fresco & pigment chemistry
Other learning objectives • elements of art history • layering & its analysis in paintings • color analysis & color spaces
Means of assessment
6) Principles of restoration & conservation (3 weeks)
• Case studies: review of four painting restorations (Gentileschi, Vermeer, Michelangelo, “Fake or Fortune”) • Lab: color selection for Gentileschi renovation
• assigned reading & videos • journal reflections • homework questions • lab report • slideshow & oral presentation • participation during class discussion
7) Authentication of provenance & forgery detection (3 weeks)
• Activity: • methods of • elements of art introduction to scientific analysis history forgery • pigment chemistry • Activity: create your own homework--the science of forgery detection • Case studies: review of four known forgeries (Vinland map, Shakespeare Flower portrait, Reinhold Vasters goldsmithing, Chagall painting) • Lab: chrome yellow spectral analysis
• assigned reading & videos • journal reflections • homework questions • lab report • participation during class discussion
Final Project (2 weeks)
• Activity: Byzantine • methods of • elements of art wall paintings in the scientific analysis history Enkleistra of St. • pigment chemistry Neophytos in Paphos, Cyprus
• written report
Pigment Synthesis Experiments What is a pigment and how is one naturally procured or chemically synthesized? What are the various components in paint? Our laboratory program for the fall term largely centered around pigment synthesis experiments which afford students the opportunity to apply fundamental laboratory skills in chemistry while reviewing and practicing their ability to write balanced, chemical equations and complete stoichiometric calculations (mole conversions, limiting and excess reactant determinations, percent yield results) in order to assess the success of their experiments. Also discussed in the context of the synthesis reactions are other, traditional chemistry topics (molecular 24
geometry, spectator ions, net ionic equations, solubility and precipitation, common ion effect, pH and acid-base equilibria, kinetics, etc.). We initially targeted four pigments for our chemical synthesis experiments: Egyptian blue (which we have conducted as a teacher-led demonstration), madder lake, cobalt green, and cobalt yellow (which have been conducted by the students themselves working in traditional lab groups). Complete experimental protocols, gravimetric results, and the specific chemical topics addressed for each of the pigment synthesis reactions are detailed in our earlier paper and its supplementary materials which describe our short course pilot program (8). For the yearlong course, time constraints set by our school’s initial COVID-19 quarantine period this past fall meant that we were unable to fully incorporate the Egyptian blue and madder lake synthesis experiments this year. The Egyptian blue synthesis was omitted entirely; for the madder lake synthesis activity, the students were provided with gravimetric data from prior synthesis experiments and asked to complete the post-laboratory questions and calculations. We were able to incorporate into the expanded curriculum the synthesis of the Prussian blue pigment which is described in detail here. For each pigment synthesis experiment, the students completed gravimetric calculations based on their mass measurements and answered follow-up questions that addressed pertinent chemistry concepts and artistic properties of the pigment (for example, hiding power, tinting strength, compatibility with various binders, suitability for the fresco method, lightfastness/permanence). Some additional elaboration and discussion of select pigment synthesis reactions (beyond what is presented in our initial paper) is helpful and is therefore presented here. Madder Lake Synthesis We observed that our students struggled to fully understand the chemical details of making a lake pigment during the madder lake synthesis in which alizarin and purpurin dyes extracted from madder roots are chemically bound to inorganic substrates. This may be due to the fact that they did not actually conduct the synthesis themselves because of time constraints related to the pandemic but instead only read the laboratory procedure and viewed photographs of the experiment before completing follow-up questions and calculations. We found it helpful and instructive to carefully walk the students through the relevant chemistry by having them consider a series of simpler reactions as components of the overall process of making a lake pigment: Dissolution of alum:
Precipitation of aluminum hydroxide:
Acidification of calcium carbonate:
Precipitation of calcium sulfate:
Cancellation of the chemical species present on both the reactant and product sides of reactions 1-4 above (Al3+, SO42-, H2O, H+, Ca2+) yields the resulting net ionic equation: 25
Or, preferably, if the alum reactant is written in its dissolved and dissociated form:
It is worth highlighting that reaction 2 actually produces an indefinite hydrate Al(OH)3·nH2O, as noted in our earlier paper. For simplicity’s sake during instruction, we chose to ignore this complication. Having students consider and balance reactions 1-4 as a build-up to writing reactions 5 and/or 6 ultimately proved to be more helpful for their overall understanding. There is ample material here for those instructors interested in addressing with their students in post-laboratory questions and calculations: 1) the molecular geometry of the organic dyes alizarin and purpurin, for example, by determining the molecular shape, hybridization, and bond angles around carbon or other atoms in the structures, 2) a more quantitative treatment of solubility-precipitation equilibria (see particularly reactions 2 and 4), for example, by calculating the ion concentrations in saturated solutions of aluminum hydroxide or calcium sulfate given their Ksp values, or by exploring Le Chatelier’s principle equilibrium shifts due to the common ion effect, and 3) the pH dependence of sulfate/bisulfate speciation. Measurements obtained during our madder lake synthesis experiments conducted between the publication of our original paper and the preparation of this one indicate that the reaction solutions had a pH of 3.87±0.35 (n=3 trials) after the addition of calcium carbonate. At this pH, equilibrium calculations suggest that sulfate should be about 90 times more abundant than bisulfate in solution, and equation 5 is therefore written to reflect this observation. Prussian Blue Synthesis Prussian blue is a hydrated iron(III) hexacyanoferrate(II) complex that was first synthesized in the early 1700s. A variety of methods have been utilized for its synthesis and two formulas for Prussian blue are common in the relevant literature (9, 10, 11): KFe[Fe(CN)6] and Fe4[Fe(CN)6]3. We obtained our experimental synthesis protocol from Mary Robert Garrett (12) as a result of her participation in the 2015 Chemistry in Art (CiA) Chemistry Collaborations, Workshops and Community of Scholars program (cCWCS) (13). No acute toxicity data exist for Prussian blue, but the USFDA considers it safe for use and it is currently utilized in cosmetics and as a medical treatment and chelating agent for radioactive thallium and cesium poisoning (14). The dry pigment, however, is a colloidal powder and inhalation of any powder is irritating to the lungs and should be avoided. When Prussian blue burns it evolves cyanogen, which is highly toxic (15). Standard safe handling procedures apply. This synthesis protocol utilizes the direct method for the synthesis of Prussian blue:
Students mixed 10.0 mL aliquots of 0.500 M FeCl3 (acidified in 0.20 M HNO3) and 0.250 M K4Fe(CN)6 at room temperature and then vacuum-filtered (using Whatman Grade 3 filter paper (16)), rinsed, dried, and weighed the resulting precipitate, which was a thick, dark blue slurry and contains iron in both its Fe+3 and Fe+2 oxidation states.
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According to Berrie (17), “The physical properties of Prussian blue complicate its preparation and purification: its low specific gravity and extremely fine grain size make the product difficult to isolate and its colloidal nature frequently causes absorbance of excess reactants or other products as impurities. These complications make gravimetric analysis of its synthesis inexact.” Although we did not experience any particular difficulty filtering the precipitate, our own gravimetric results confirmed the complications Berrie described: calculated yields obtained for four synthesis trials were both high and highly variable with an average value of 132±37% . The reaction and its synthesis procedure offer the opportunity to address with students the possibility and potential causes of experimental yields greater than 100%, variable oxidation states in metals, and concentration expressions with a review of molarity calculations. Cobalt Green Synthesis A synthesis reaction for the double salt cobalt green is shown below:
We are aware that there is some question as to whether cobalt green is a compound at all--that it instead may be a solid solution of cobalt and zinc oxides (Rinmann’s green (18, 19)). We are unaware of more recently published investigations addressing this specific question. It could be interesting material for instructors with access to appropriate analytical methods (for example, X-ray powder diffraction) to explore with their students. Care should be taken to conduct the cobalt green synthesis reaction in a fume hood or wellventilated room to avoid breathing the noxious chlorine gas produced, and the resulting cobalt pigment should be handled with care. Excess pigment should be disposed of properly. This synthesis experiment is an intriguing one from a gravimetric perspective because it allows for some assessment of the success of the synthesis based on the consideration of two different gravimetric calculations: mass loss (due to the release of water vapor and chlorine gas) and yield of cobalt green powder recovered. For the target reactant amounts in the protocol we adopted from the Pigments through the Ages website (20) (1.00 g of cobalt(II) chloride hexahydrate and 5.00 g of zinc oxide), mass loss and pigment yield are expected to be close to 12.5% and 100%, respectively. A plot of the calculated values for the mass loss versus the pigment yield for individual synthesis trials conducted over the several years we have experimented with this reaction generally yields a continuum from less successful to more successful to theoretical results (Figure 1). It is also worth addressing with students that the cobalt green synthesis protocol presented on the Pigments through the Ages website does not reflect a stoichiometric proportion of the reactants cobalt(II) chloride hexahydrate (limiting) and zinc oxide (in excess). This begs the question, why not? Chemistry students might think this to be an unnecessary waste of the excess zinc oxide, so it is worth asking them what other rationale might exist for a formulation that includes a nonstoichiometric proportion of reactants. Hopefully, this encourages students to think along more interdisciplinary lines and prompts them to consider the artistic properties of the pigment (color, tinting strength, hiding power, etc.) that may be more desirable given a non-stoichiometric reactant mixture. It might also prompt additional questions that are readily testable via experiment: What happens to CIE L*a*b* colorimetric coordinates of the resulting cobalt green pigment if less zinc oxide is used in its formulation? Gettens and Stout suggest that “the color, which is a bluish green, remains much the same with widely varying proportions of cobalt (21).” This could be confirmed easily and quantitatively by students conducting coupled gravimetric and colorimetric experiments. Such 27
questions relating the stoichiometry and quantitative colorimetry of colorants are common in modern dye and pigment research (22).
Figure 1. A plot of the percentage of initial reactant mass loss due to evolution of volatile gases versus the percent yield of cobalt green pigment. The red diamond represents the theoretical values expected for a trial using 1.00 g of cobalt(II) chloride hexahydrate with 5.00 g of zinc oxide. Open blue squares represent teacher-conducted experiments completed during the design of the course; filled green circles represent the results of student laboratory groups from two different iterations of the synthesis experiment. Excess mass loss and low percent yields (upper left) are attributed to spillage during heating, stirring, and weighing. A low percent mass loss and a high percent yield (lower right) is attributed to an incomplete reaction.
UV-Vis-NIR Fiber Optic Spectroscopy Measurements How can we scientifically identify materials that produce color? How can we measure color? How do humans see and quantitatively represent color? In a typical introductory general chemistry course, consideration of color is usually limited to: 1) flame tests for the qualitative analysis and identification of cations, and/or 2) Beer’s Law applications that relate the absorbance of specific wavelengths of light to the concentration of dissolved salts that produce colored solutions. Sattar (23), however, recently demonstrated the ease and applicability of using portable, hand-held, fiberoptic reflectance spectrophotometers that measure the light reflected from a colored surface to advance students’ understanding of the color of powdered solids produced during pigment synthesis experiments. There are numerous aspects of fiber optic spectroscopy that particularly excited us and prompted its inclusion in the curriculum of our new course. 1) We were already in possession of an Ocean Optics spectrophotometer with a fiber optic cable capable of absorption measurements, so no additional expense was incurred. 2) Data collection is quick and straightforward (for example, we were able to collect spectra for half a dozen pigments from each of our three laboratory groups in 28
a matter of just a few minutes). 3) The data reduction affords an opportunity to teach spreadsheet programming skills to students. 4) The colorimetric results allow for the quantification of color and a means to search for new connections between variations in experimental procedures or gravimetric results and color as described by CIE L*a*b* colorimetric coordinates. 5) Particular absorption features in the spectra obtained are directly attributable to specific chemical aspects of the pigments, allowing for spectral fingerprinting and direct comparison with spectral databases for pigment identification. 6) The methods introduce students to the basic concepts of spectroscopy in general and set the stage for their additional study later in the course of other spectroscopic methods: Xray diffraction (XRD), X-ray fluorescence (XRF), Raman scattering, and Fourier transform infrared (FTIR) spectroscopy. 7) The methods are applicable to other materials of cultural heritage value (ceramics, metals, glasses), which are planned as additional subjects of study during the winter term of our new class. We therefore adopted and adapted fiber optic spectroscopy methods for inclusion as a significant component of the laboratory program in our new course. Our analytical methods are described in an earlier paper (24); they involve the use of instrumentation that is relatively inexpensive and readily accessible to high school and college laboratory programs together with publicly available spreadsheets for conversion of UV-Vis-NIR spectra to colorimetric coordinates. Absorption spectra were collected using Vernier software with an Ocean Optics spectrophotometer equipped with a fiber optic cable. Operating conditions were maintained at 50 ms integration time, sampling every 2 nm from 388−950 nm wavelength, and averaging 30 samples per spectrum. Data were first reduced in our own spreadsheets by 1) converting absorbance values to reflectance values, 2) conducting a “dark” subtraction using a spectrum obtained with the cap in place over the end of the fiber optic cable, 3) performing a white normalization to BaSO4, and 4) smoothing to a five-point average reflectance measurement centered on each wavelength. In order to obtain CIE L*a*b* coordinates and RGB values for color quantification and digital color reconstruction the spectra were then 5) condensed to a 5 nm sampling interval between 390 and 830 nm, and 6) copied into a spectral calculator spreadsheet (25) (the 2-degree A illuminant was used). We would like to take this opportunity to correct an inadvertent error in the earlier paper in which we accidentally mischaracterized the geometry of the illumination source and the fiber optic cable: for all of our measurements, samples were illuminated using an incandescent flashlight, providing sufficiently uniform illumination from the UV to the NIR, oriented perpendicular to the pigment sample surface with the fiber optic cable oriented at approximately 45° to both the incident light and the colored surface. This arrangement provides the necessary diffuse measurement (Figure 2). We will henceforth refer to these measurements, based on the use of the fiber-optic cable and the calculation of reflectance values from absorbance data, as fiber-optic reflectance spectroscopy (FORS). Additionally, we have undertaken a reproducibility study of pigments synthesized in our laboratory by obtaining ten spectra of a cobalt green powder and nine spectra of a gouache watercolor paint made with madder lake. Average values and standard deviations of colorimetric coordinates in the most commonly used color spaces are summarized in Table 2 and provide an estimate of the analytical uncertainty of our colorimetric methods. In addition to the pigments that the students in the yearlong course synthesized themselves (Prussian blue, cobalt green, cobalt yellow), they were provided with powdered samples, previously synthesized by the instructor, of madder lake and Han blue powders for paint preparation and spectroscopy measurements. Students obtained reflectance spectra from both dry pigment powders and their gouache watercolor paints which were applied in thumbnail-sized swatches to a 3x5” index card. Examples of diffuse reflectance spectra for the various powdered pigments we have synthesized 29
and analyzed to date are shown in Figure 3. CIE L*a*b* colorimetric coordinates obtained using these methods are listed in Table 3 and plotted in Figure 4; they quantify the colorimetric reproducibility of the various synthesis experiments (for comparison, see also Sattar (26) Table 1, Figure 1, and Figure 3; Vyhnal et al. (27) Table 2, Figure 3, and Figure 4).
Figure 2. Experimental set-up for fiber optic spectroscopy measurements of pigment powders and gouache watercolor paints. Methods generally follow Vyhnal et al. (2020) (28); absorption spectra were collected using Vernier software with an Ocean Optics spectrophotometer equipped with a fiber optic cable. Operating conditions were maintained at 50 ms integration time, sampling every 2 nm from 388−950 nm wavelength and averaging 30 samples per spectrum. Data were first reduced in our own spreadsheets by 1) converting absorbance values to reflectance values, 2) conducting a “dark” subtraction using a spectra obtained with the cap in place over the end of the fiber optic cable, 3) performing a white normalization to BaSO4, and 4) smoothing to a five-point average reflectance measurement centered on each wavelength. In order to obtain CIE L*a*b* coordinates and RGB values for color quantification and digital color reconstruction the spectra were then 5) condensed to a 5 nm sampling interval between 390 and 830 nm, and 6) copied into a spectral calculator spreadsheet (29) (the 2-degree A illuminant was used). Photo by C.R. Vyhnal.
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Table 2. Estimate of Analytical Uncertainty in Colorimetric Coordinates 10 measurements of powdered cobalt green pigment
9 measurements of madder lake gouache watercolor paint
Colorimetric Coordinates
Average Value
1σ Standard Deviation
Average Value
1σ Standard Deviation
CIE L* a* b*
50.06 -18.47 -4.91
0.79 0.32 0.52
64.50 22.98 13.43
0.37 0.09 0.27
Apple R G B
66.9 116.6 102.8
1.1 2.4 2.7
173.2 114.7 116.7
1.4 1.0 1.3
Adobe R G B
99.1 133.4 121.9
1.5 2.2 2.8
175.4 134.2 134.3
1.1 1.0 1.0
Figure 3. Examples of diffuse reflectance spectra obtained from dry pigment powders synthesized in our own experiments during course development. The colors of the spectra reflect their actual RGB color coordinates converted from CIE L*a*b* colorimetric values. Along the right margin of the graph from top to bottom the spectra are: madder lake, Han blue, cobalt yellow, cobalt green, Egyptian blue, Prussian blue. Adapted with permission from reference (30). Copyright 2020 Journal of Chemical Education.
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Table 3. CIE L*a*b* Colorimetric Coordinates of Pigment Powders and Gouache Paints Powders Pigment Egyptian blue
Han blue
Prussian blue
Madder lake
Cobalt green
Gouache Paints
Group
L*
a*
b*
L*
a*
b*
CHSOSa
60.55
-8.25
-31.77
54.16
-3.39
-30.99
0b (fine)
55.39
-16.75
-35.86
0 (coarse)
39.58
-9.04
-57.59
0
70.70
-12.58
-36.89
0/1c
68.10
-15.92
-50.34
66.96
-17.03
-45.65
0/3
68.10
-15.92
-50.34
55.59
-13.92
-40.27
0/5
68.10
-15.92
-50.34
71.98
-15.94
-38.16
CHSOS
45.37
0.03
-15.03
50.22
0.28
-5.27
0
0.12
2.65
-18.20
1d
3.64
7.49
-15.49
3
0.11
2.40
-14.30
5
1.72
6.58
-26.87
CHSOS
71.75
23.30
10.44
73.13
27.91
17.41
0
64.28
22.50
15.55
0
64.22
28.87
20.45
0/1c
66.32
24.84
18.38
63.91
22.98
11.91
0/3
66.85
27.87
19.24
76.67
16.11
7.16
0/5
67.46
23.55
17.85
74.26
28.21
22.87
CHSOS
64.86
-21.46
7.20
61.68
-15.78
3.67
0
56.07
-14.27
-4.36
0
62.19
-14.58
-6.80
1
60.76
-16.98
-4.44
76.45
-14.39
-4.69
3
54.01
-19.53
-5.73
68.32
-12.49
-5.00
5
52.86
-21.26
-5.19
49.72
-23.19
-8.53
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Table 3. (Continued). CIE L*a*b* Colorimetric Coordinates of Pigment Powders and Gouache Paints Powders
Gouache Paints
Pigment
Group
L*
a*
b*
L*
a*
b*
Cobalt yellow
CHSOS
93.70
14.76
64.68
86.91
12.99
52.80
0
71.06
12.13
71.65
0
72.98
11.61
72.28
1
67.44
15.70
75.06
89.43
11.88
60.28
3
75.69
17.89
83.12
86.12
14.10
40.87
5
72.07
18.19
81.83
84.64
15.49
86.75
a Colorimetric
coordinates obtained from the FORS spectra in the earlier CHSOS Pigments Checker v3.0 (31) release are provided for comparison with our own results. b Group 0 represents teacher synthesis and analysis trials completed during course development. c Samples labeled with a zero followed by a number (for example: Han blue and madder lake 0/1), represent pigments that were synthesized by the instructor and provided to a student lab group to make paints for their colorimetric analysis and subsequent artwork. d Groups 1, 3, and 5 represent student synthesis and analysis trials completed at socially distant lab stations during the course this past fall.
Several conclusions can be drawn from our colorimetric analyses of synthesized pigment powders and the gouache watercolor paints made with them. 1) The color of pigment powders was fairly reproducible across different experiments completed by different laboratory groups. Colorimetric coordinates were generally similar (see Table 3), and their values were reasonably wellclustered in CIE b* versus a* colorimetric space (see Figure 4). 2) The color of gouache watercolor paints made with the pigments was less reproducible across different laboratory groups. Generally speaking, gouache watercolor paints were a lighter shade than the pigments themselves (both visually-assessed and as indicated by higher L* values), but this was not universally true: Group 1’s madder lake paint was darker than their pigment; Group 5’s cobalt green paint was darker than their pigment. Likewise, the difference in CIE L*a*b* values between pigment and paint was not consistent from one pigment to the next or from one laboratory group to the next (Table 3). 3) The trend of paints being generally lighter than their powdered pigment form is interpreted to reflect dilution and lightening of the pigment through addition of the gum arabic binder (see discussion in Sattar (34) and references therein) and/or a reduction in pigment particle size during grinding and homogenization of the pigment and binder (35, 36). The students themselves attributed the greater variability in paint color to variations in the proportion of binder to pigment used and/or the density of paint application on the index cards across laboratory groups. 4) The disparity in L* values between the Cultural Heritage Science Open Source (CHSOS) and our own are attributed to variations in spectral standardization (in the CHSOS data v3.0 data, no dark subtraction was performed and a Spectralon white standard was used for white normalization, Antonino Cosentino, pers. comm. (37); the CHSOS database will be discussed in greater detail in a subsequent section).
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Figure 4. Plot of CIE colorimetric coordinates b* vs a* for the powdered pigments listed in Table 3. a* indicates color from greens (at negative values) to reds (at positive values). b* indicates color from blues (at negative values) to yellows (at positive values). The colors of the points reflect their actual RGB color coordinates converted from CIE L*a*b* colorimetric values. Clockwise from top the clusters are: cobalt yellow, madder lake, Prussian blue, Egyptian and Han blues, cobalt green. Closed circles: Thacher analyses; open circles: CHSOS Pigments Checker v3.0 (32) FORS data, provided for comparison. Adapted with permission from reference (33). Copyright 2020 Journal of Chemical Education.
Several questions arose during our FORS investigations of synthesized pigments that time constraints due to our COVID-19 modified schedule precluded us from exploring further: How does the pH of the madder extract or reactant solutions affect the color of the pigment obtained? What is the relationship between the amount of excess zinc oxide used and the color of cobalt green pigment synthesized?
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Figure 5. Screen captures of Vernier’s Logger Pro (40) software that show how reflectance spectra can be analyzed to identify a local minimum in reflectance (for example, an absorption peak) for comparison with those identified in other studies. a) Using the Analyze/Statistics option on a highlighted data range to find the wavelength of the reflectance minimum. b) Fitting lines to the limbs on either side of a local minimum in the first derivative of reflectance and then using the Analyze/Examine option to find the intersection of the lines and the wavelength of the reflectance minimum.
Beyond their use in obtaining colorimetric values that allow for quantitative comparisons and digital reconstructions of color (38), the spectra obtained also allow for the identification of absorption features due to specific chemical properties of the pigments. So, we had our students 35
identify local reflectance minima (absorption peaks) in the spectra they obtained by copying their reduced spectra from Excel and pasting them into Vernier’s Logger Pro software (39). Vernier’s software and chemical probeware are widely used in high school and college chemistry laboratory programs, and Logger Pro has several features that are well-suited to spectral data analysis of this kind. Students can highlight a range of data around an expected reflectance minimum and use the Analyze/ Statistics pull-down option to find the precise, minimum reflectance value in the highlighted wavelength range and the specific wavelength at which it occurs (Figure 5a). Alternatively, students can use the Data/New Calculated Column option with the Delta function to calculate and plot the first derivative of the spectrum. They can then highlight the data that represent the limbs on either side of a local minimum, fit lines to the data on either side of the local minimum, and use the Analyze/ Examine option to find the intersection of the two lines which yields an objective estimate of the wavelength of the local minimum (Figure 5b). We had our students focus their efforts at identifying absorption features by examining the spectra of the cobalt green pigment, which allowed them to practice both of the methods described above. Their analysis was performed on cobalt green spectra obtained from both the dry pigment powders and the resulting gouache watercolor paints and yielded three clear absorption features at 554 ±2 nm, 598 ±2 nm, and 648 ±2 nm (n = 6 measurements), in excellent agreement with those identified (near ~542 nm, ~594 nm and ~643 nm) in a study of Co+2 in pigments (smalt, cobalt blue, cobalt violet) and glasses (see the 11 analyses in Table 1 of Bacci and Picollo, 1996 (41)). The fact that such absorption features are noticeably absent in the cobalt yellow spectra provides a natural segue into a discussion of oxidation states, given that cobalt in the cobalt yellow pigment exists in its +3 valence state, whereas cobalt in cobalt green pigment exists in its +2 valence state; this comparison clearly illustrates for students the power of non-invasive, diffuse reflectance spectroscopy to reveal meaningful chemical information above and beyond mere colorimetric characterization. Although we did not have our students identify absorption features in the other pigments in this iteration of the course due to pandemic time constraints we plan to do so in the future. Reflectance minima obtained for all of the pigments that we have thus far synthesized and analyzed (except Prussian blue, which has a relatively flat and featureless reflectance profile in the visible and near infrared portion of the spectrum), their standard deviations, and the number of measurements (n) on which these values are calculated are compared with those previously identified and discussed in the literature and summarized in Table 4. The correspondence of the absorption features we have identified using the methods described above with those referenced in the scientific literature is encouraging and speaks to both the success of our synthesis experiments and the validity of our FORS methods. Because reflectance spectroscopy can be a powerful, diagnostic tool for the identification of certain pigments (and other materials), characterization of specific absorption features in reflectance spectra is a fundamental component of non-invasive analyses in cultural heritage science research. Identification of such absorption features in reflectance spectra also points the way to another non-invasive analytical method, photoluminescence imaging, as areas of peak absorbance represent good targets for the wavelengths of incident light needed to excite certain pigments with distinct photoluminescence properties (for example, Egyptian blue, Han blue, madder lake) and induce luminescence at longer wavelengths in the electromagnetic spectrum (52, 53, 54, 55).
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Table 4. Measured Absorption Features for Synthesized Pigments and Comparison with Those Identified in the Literature Absorption Features Identified (nm)
Pigment
Absorption Features in the Literature (nm)
~628, ~786 (n=1)
~560, 628, ~790 (42) 622, 771 (43).
Han blue
629 ±1, 812 ±1 (n=4)
~620 (44) 518, 627, 804 (45) 594, 785 (46)
Madder lake
502 ±4, 542 ±3 (n=6)
510, 540 (47) 512, 543 (48)
Cobalt green
554 ±2, 598 ±2, 648 ±2 (n=6)
~542, ~594, ~643 (49)
Cobalt yellow
456 ±5, 794 ±5 (n=6)
443 (50) 2400-2500 (51), a
Egyptian blue
a The absorption features identified by Cloutis et al. (51) fall outside the range of wavelengths accessible to our
spectrophotometer.
Painting a Fresco Tile: Chemical Reactions in the Fresco Lime Cycle What is a fresco painting and why have some ancient fresco paintings survived for thousands of years? Fresco painting is a method by which pigments are applied to still-wet plaster which then dries and chemically binds the pigment in place (56). As our culminating final project for the fall term we had our students create a fresco tile (57) that they painted with the pigments they chemically synthesized. We introduced the project with a slideshow that included a discussion of the fresco lime cycle reactions with relevant history and images of important works of art that utilized the fresco technique. A sound conceptual understanding of the chemical reactions that comprise the fresco lime cycle together with practical experience painting in the fresco technique represent important components of the students’ learning experience that are revisited in our course in a subsequent unit on the chemistry of art restoration and conservation concerns. The chemical reactions in the fresco lime cycle include: Decomposition of calcium carbonate (fossil shells or limestone) to make quick lime:
Addition of quick lime (a basic anhydride) and water to synthesize slaked lime:
Reaction of slaked lime with atmospheric CO2 and dehydration to make calcium carbonate:
The students started with a 6-inch square, unglazed, ceramic tile representing the “muro” (Italian for “wall”). They then applied a base layer of plaster (the “arriccio”, Italian for “curl”) composed of a mixture of slaked lime, clean quartz sand, and water. Arriccio layers in frescoes are coarser and thicker and serve as preparatory layers for the surface to be painted. After this layer 37
had dried for several days, the students applied a final layer of slaked lime, sand, and water (the “intonaco”, Italian for “plaster”). The intonaco is a much thinner, fine-grained, final layer prepared for direct application of the pigment. A design of the students’ choosing was sketched on a piece of tracing paper (a “cartoon”), and the drawn lines were perforated with a thumbtack to pierce the tracing paper. The students then placed their tracing paper on the still wet plaster tile, and, using a sock filled with vine black charcoal powder, gently dabbed their tracing paper and tile with the sock, transferring the powdered charcoal through the holes in the tracing paper to the intonaco (a process known as “spolvero”, Italian for “pouncing” (58); demonstrations of the process are available on YouTube (59)). Students then completed their fresco tiles with the paints they made from their synthesized pigments (Figure 6). We also purchased English red earth and yellow ochre watercolor paints from an art supplier (60) out of concern that our synthesized madder lake and cobalt yellow pigments were unsuitable for the fresco method (see discussions in Schweppe and Winter (61) and Cornman (62), respectively), but most of our students elected to use their synthesized pigments anyway and no adverse consequences have yet been observed. Their madder lake and cobalt yellow pigments seem to be colorfast in fresco over the short term, but we nevertheless obtained baseline diffuse reflectance measurements on one of the tiles after it dried for future comparisons. One student decided to include Prussian blue on his tile despite the fact that it is also known to be unsuitable for the fresco method (63) precisely because he wanted to see what would happen, and he observed almost immediately discoloring of the deep blue pigment to a dark brown.
Figure 6. a) Tracing paper cartoon for pouncing (“spolvero”) transfer of vine black to the wet plaster as part of the fresco technique. b) Finished fresco tile that incorporates provided pigments (red earth, Han blue) and those pigments the student synthesized from the laboratory modules (cobalt yellow, cobalt green). In the top left corner are visible the ceramic tile itself (representing the wall or “muro”), the rough plaster layer (“arriccio”), and the fine plaster layer (“intonaco”) on which the hummingbird is painted. Artwork by Avery Budlong is reproduced here with her permission. Photos by C.R. Vyhnal. It is also worth noting that we used the same relatively coarse, quartz sand for both the arriccio and intonaco layers of the fresco tile; in the future we will look to obtain a finer sand for the intonaco layer to provide students with a smoother surface on which to paint.
38
The final report for the project had the students answer practical questions about the fresco method: How are lime and slaked lime made? Why is it important to prepare the cartoon beforehand and paint quickly? Which pigments are chemically incompatible with the fresco technique and why? Students then completed standard stoichiometric calculations related to the lime cycle reactions and wrote a balanced equation for the deterioration of fresco plaster in the presence of an acidic solution. Although we did not incorporate standard calorimetric and thermochemical calculations into the final project this year, we plan to include these concepts in future iterations of the analysis. Since the fresco lime cycle reactions are cyclical (starting with calcium carbonate and ending with calcium carbonate), the reactions represent a good opportunity to graphically demonstrate to students the path independence of enthalpy (since the enthalpy changes for reactions 9-11 sum to zero). Teachers could also choose to incorporate other standard thermodynamic calculations (entropy and Gibbs’ free energy changes) based on the fresco lime cycle reactions, although we have opted instead to cover them in a subsequent activity on the chemistry of Attic black-and red-figure pottery (64, 65), the details of which will be described in a future publication (Vyhnal, in preparation (66)). Through their understanding of the fresco lime cycle reactions and the creation and handling of their fresco tiles, our students are in a better position to more fully understand and appreciate how the fresco method was used to produce wall paintings capable of surviving for centuries beyond the lifetimes of both artists and civilizations and why pigments that are chemically incompatible with the fresco method were instead applied using the secco (dry) method. Further, students will apply their understanding of fresco lime cycle chemistry when we consider art restoration and conservation topics later in the course.
Using the Cultural Heritage Science Open Source (CHSOS) Spectral Databases as a Resource for Pigment Identification and an Instructional Tool for Analytical Chemistry How do we identify pigments and other painting media in a decorated object or painting, preferably without taking samples and potentially damaging the artwork? A major emphasis in the characterization, conservation, and restoration of works of art and cultural heritage objects is the use of multi-faceted and preferably non-invasive analytical methods whenever and wherever possible. In recent years, a number of technological advances and informational resources have assisted scientists and conservators in this endeavor. According to their self-description, the Cultural Heritage Science Open Source (CHSOS) “is a private practice service specialized in on-site examination and documentation of works of art with technical photography and analytical techniques that also provides related training and consulting for private professionals and institutions. CHSOS clients are art collectors, museums and private professionals, such as conservators, art historians and art appraisers (67).” Fortunately, for chemistry educators interested in the spectroscopic imaging, characterization, and identification of pigments, CHSOS has made publicly available, free of charge, analytical spectra from techniques capable of non-invasive analyses (FORS (68), Raman (69), and XRF (70)) for fifty-eight archaeological and historical pigments. Recent expansions of the database include new Raman spectra with additional laser excitations at 830 and 1064 nm, near-infrared (NIR) reflectance spectra from 930-1690 nm, and Fourier transform infrared (FTIR) spectra. File types available for download from the CHSOS website include text files (.txt), comma-separated value files (.csv), and DPPMCA ascii files (.mca). (DPPMCA is a Windows software application that provides data acquisition, display, and control for Amptek signal processors; the application is available as a free download (71).) The CHSOS list of pigments for which spectra are available 39
continues to increase and currently includes eighty-one archaeological, historical, and modern pigments (Table 5) (72). Table 5. Cultural Heritage Science Open Source (CHSOS) Pigments Checker v5 Data Ramanb (wavelengths in nm) Spectra:
FORSa
532
785
830
1064
XRFc
NIRd
FTIRe
File Typef:
.txt
.txt
.csv
.csv
.csv
.mca
.csv
.csv
Color
Pigment
Whitesg
antimony white (PW 11)
X
chalk
X
X
X
gypsum
X
X
X
lead white
X
X
X
lithopone
X
X
titanium white
X
zinc white Yellows
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
arylide yellow 5GX
X
X
X
X
X
X
X
X
cadmium yellow
X
X
X
X
X
X
X
X
chrome yellow
X
X
X
X
X
X
X
X
cobalt yellow
X
X
X
X
X
X
X
X
curcuma
X
X
X
X
X
X
X
gamboge
X
X
X
X
X
X
X
Hansa yellow (PY 3)
X
X
X
X
lead tin yellow I
X
X
X
X
X
lead tin yellow II
X
X
X
X
massicot
X
X
X
Naples yellow
X
X
nickel azo yel (PY 150)
X
orpiment
X
safflower (NY 5)
X
saffron
X
X
X
X
X
stil de grain
X
X
X
X
X
yellow lake Reseda
X
X
X
X
X
X
yellow ochre
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
40
X
X
X
Table 5. (Continued). Cultural Heritage Science Open Source (CHSOS) Pigments Checker v5 Data Ramanb (wavelengths in nm) Spectra:
FORSa
532
785
830
1064
XRFc
NIRd
FTIRe
File Typef:
.txt
.txt
.csv
.csv
.csv
.mca
.csv
.csv
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Color
Pigment
Reds
alizarin
X
X
X
cadmium red
X
X
X
carmine lake
X
X
X
lac dye
X
X
X
madder lake
X
X
X
naphthol red
X
X
X
X
X
pyrrole red (PR 264)
X
X
X
X
X
realgar
X
X
X
X
X
X
X
X
red lead
X
X
X
X
X
X
X
X
red ochre
X
X
X
X
X
X
rhodamine (PR 81)
X
X
X
vermilion (nat)
X
vermilion (syn) Greens
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
cadmium green
X
X
X
X
X
X
X
X
chrome oxide green
X
X
X
X
X
X
X
X
cobalt titanate green
X
X
X
X
X
X
X
copper resinate
X
X
X
green earth
X
X
X
malachite
X
X
X
naphthol green (PG 12)
X
X
X
X
phthalo green
X
X
X
X
verdigris
X
X
X
viridian
X
X
X
41
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Table 5. (Continued). Cultural Heritage Science Open Source (CHSOS) Pigments Checker v5 Data Ramanb (wavelengths in nm) Spectra:
FORSa
532
785
830
1064
XRFc
NIRd
FTIRe
File Typef:
.txt
.txt
.csv
.csv
.csv
.mca
.csv
.csv
X
X
X
X
X
X
X
X
X
X
X
X
Color
Pigment
Blues
azurite
X
X
X
blue bice
X
X
X
cobalt blue
X
X
X
X
cobalt cerulean blue
X
X
X
X
cobalt chromite blue
X
X
X
X
X
X
X
cobalt violet
X
X
X
X
X
X
X
Egyptian blue
X
X
X
X
X
X
Han blue
X
X
X
X
X
X
indigo
X
X
X
X
X
X
X
manganese violet
X
X
X
X
X
X
X
Maya blue
X
X
X
X
X
X
X
methylene blue (BB-9)
X
phthalo blue
X
X
X
Prussian blue
X
X
X
smalt
X
X
X
Tyrian purple (NV1)
X
ultramarine (nat)
X
X
X
X
X
ultramarine (syn)
X
X
X
X
X
vivianite
X
X
bitumen
X
burnt Sienna
Browns
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
burnt umber
X
X
X
X
X
raw Sienna
X
X
X
X
X
X
X
raw umber
X
X
X
X
X
X
sepia
X
X
X
X
X
X
Van Dyke brown
X
X
X
X
X
X X
42
X
X
Table 5. (Continued). Cultural Heritage Science Open Source (CHSOS) Pigments Checker v5 Data Ramanb (wavelengths in nm) Spectra:
FORSa
532
785
830
1064
XRFc
NIRd
FTIRe
File Typef:
.txt
.txt
.csv
.csv
.csv
.mca
.csv
.csv
X
X
X
Color
Pigment
Blacks
aniline black (PBk 1)
X
bismuth metal powder
X
bone black
X
X
X
X
iron gall ink
X
X
X
X
ivory black
X
X
lamp black
X
vine black
X
X X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
a Fiber optic reflectance spectra (FORS) were obtained from 360-940 nm wavelength.
X
b Raman spectra were
obtained at 532, 785, 830, and 1064 nm excitation wavelength. fluorescence spectra (XRF) were collected over 2048 channels to between 36 and 39 keV depending on the specific instrument calibration results. d Near-infrared reflectance spectra (NIR) were obtained from 934-1690 nm wavelength. e Fourier transform infrared spectra (FTIR) were obtained from wavenumbers of 650 to 4000 cm-1. f File types available for download from the CHSOS website include text files (.txt), comma-separated value files (.csv), and DPPMCA ascii files (.mca). (DPPMCA is a Windows software application that provides data acquisition, display, and control for Amptek signal processors; the application is available as a free download (75).) CHSOS spectra in the Pigments Checker v5 release were obtained from pigments in acrylic binders except for the Raman spectra at 830 and 1064 nm which were obtained on dry powders. g CHSOS pigments are sorted by color and then listed alphabetically by name together with the various spectra available (denoted by X) in the Pigments Checker v5 data release. c X-ray
In order to generate curricular materials and classroom activities that enhance case studies with readily accessible and authentic data and to familiarize our students with the various methods of spectroscopic analysis we have downloaded the CHSOS spectral files and imported them into Vernier’s Logger Pro software. The resulting Logger Pro files of CHSOS data provide “ready-toanalyze” spectra for a suite of historically significant pigments. Students can use the various Logger Pro data analysis functions described previously to scroll a cursor over the provided spectral profiles of an “unknown” pigment, find and record its spectral features and compare the results with “known” spectra for pigment fingerprinting and identification. We will incorporate the resulting CHSOS/Logger Pro spectral analysis database into at least two of the units planned for the spring term of our new course when we cover methods of scientific analysis and authentication of provenance / forgery detection. Three classroom activities that utilize the database are currently in development and nearing completion. One activity will have students examine CHSOS Pigments Checker v3.0 XRF spectra (73) to identify peaks related to: 1) atmospheric argon, 2) the molybdenum filament primary X-ray source in the XRF instrument, and 3) presumed refraction of the secondary X-ray beam in the silicon wafer that acts as the instrument’s detector (in order to distinguish these features from peaks related to the chemistry of a specific 43
pigment sample). A second exercise will have students examine spectra ostensibly obtained from the yellow paint used in the famous Shakespeare Flower portrait to identify it as the anachronistic chrome yellow pigment and thereby determine that the portrait is a forgery (74). A third project will have students analyze various spectra from numerous colors in the wall paintings at the Enkleistra of St. Neophytos in Paphos, Cyprus to identify the pigments used, and together with their consideration of the stylistic attributes of the painted iconography, thereby constrain the timing of the paintings to be consistent with the Byzantine period (76, 77). These and similar exercises we hope to develop in the near future emphasize the multi-faceted analytical approach that is typically used in the scientific characterization of cultural heritage works. These activities will place students in the role of “scientific sleuths” using the chemical knowledge and skills they have acquired and developed throughout our course to solve engaging and intellectually stimulating riddles of art history.
Concluding Thoughts Our preliminary efforts at recasting our instruction of introductory, inorganic chemistry concepts in the broader context of their applications in archaeology, art history, studio art, and art conservation science leave us thoroughly encouraged and excited. Many of the topics covered in a traditional general chemistry course can be examined within the framework of archaeological and historical pigments without necessarily “diluting the chemistry” by sacrificing either the breadth of coverage or a quantitative treatment of the material. We have observed that the “Why are we doing this?” question is less frequently asked of the instructor because the answers are more readily apparent to the students. Thus far, student feedback on our pedagogical shift has been overwhelmingly positive. Example reflections from two of our students at the conclusion of the fall term included: “I learned that I really enjoyed doing a lot of hands-on learning in the form of labs when it comes to chemistry related to art. I hope to develop a deeper appreciation for the art we are learning about as I learn more about how the art is created.” “I learned that I am a lot more capable of understanding the chemistry behind pigments than I thought I was, and that putting in the work to truly understand things really pays off. I also learned how interesting the chemistry behind things that we see in everyday life is and how it can also help us discover new things about history and how people lived in the past. I want to do more work like this in the future.” The curricular materials here described on the chemistry of pigments represent about a third of the content that will be covered in our yearlong course. Additional units in the winter trimester of the course will explore the chemistry of pottery, metallic artifacts, and glasses through reading and discussion of primary source materials and case studies in the field of archaeometry, coupled with focused, qualitative discussion questions and quantitative problem sets on the readings and related laboratory work. In the spring term we will review with students the methods of scientific analysis that are typically used in archaeometry, art history, and art conservations studies, followed by an introduction to the chemistry behind art restoration and conservation. A final unit on the chemistry of forgery detection will conclude the course (Table 1). It was our introduction to the discovery of the Egyptian blue pigment as potentially the first evidence of intentional chemical synthesis by humans (78), not to make something functional but rather to make something beautiful, that prompted us to contemplate a curricular overhaul of our advanced chemistry class and instead center it around chemistry applications in archaeology and art. 44
Archaeological and historical pigments provide to students a compelling narrative and a natural entry point into consideration of the study of chemistry not as an end in-and-of-itself, but rather as a means to a richer and more complete understanding of other intriguing fields of study. It is our hope that the curricular materials described here will prove as inspirational and intellectually stimulating for our future students and other chemistry educators as they have been for us.
Acknowledgments Vyhnal sincerely thanks The Thacher School for providing financial support to attend the 2017 ChemEd Conference in Brookings, SD, the 2018 Biennial Conference on Chemical Education in Notre Dame, IN, and the 2019 American Chemical Society National Convention in Orlando, FL which provided the inspiration for many of the ideas developed and presented here. Radpour is grateful for the opportunity provided by The Thacher School to join the pigment short course and participate as a guest lecturer and laboratory module developer. Mary Virginia Orna, Ioanna Kakoulli, and Yuan Lin provided expertise, resources, and encouragement as we developed our short course pilot program and its expansion into the yearlong course--their support is much appreciated. Mary Virginia Orna also provided helpful suggestions for improvement of an early draft of this manuscript for which we are very grateful. Antonino Cosentino was very responsive and generous with his time in answering questions about the CHSOS database--his assistance is gratefully acknowledged. The outline of the new course and most of the resulting curricular materials were developed during Vyhnal’s 2019-2020 sabbatical year which was generously supported by The Thacher School. We would like to thank our students in the new ChemAAA course for their enthusiasm and patience as we work out the kinks in delivering a new curriculum on a modified schedule during a pandemic, and to Avery Budlong in particular for sharing her fresco tile to image for this paper. This chapter benefitted from thoughtful, detailed, and constructive reviews by Mary Robert Garrett and two anonymous reviewers. We also thank the editors, Kristin Labby and Kevin L. Braun, for providing us with the opportunity to put these ideas in front of a larger audience.
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43. Pigments Checker v.5; https://chsopensource.org/pigments-checker/ (Accessed Feb 9, 2021). 44. Chen, Y.; Shang, M.; Wua, X.; Feng, S. Hydrothermal Synthesis, Hierarchical Structures and Properties of Blue Pigments SrCuSi4O10 and BaCuSi4O10. Crys. Eng. Comm. 2014, 16, 5418–5423. 45. Zhang, C.; Zhang, N.; Wang, X.; Zhang, L. Novel Preparation of an Ancient Ceramic Pigment BaCuSi4O10 and Its Performance Investigation. Materials Research Bulletin 2018, 101, 334–339. 46. Pigments Checker v.5; https://chsopensource.org/pigments-checker/ (Accessed Feb 9, 2021). 47. Kakoulli, I.; Radpour, R.; Lin, Y.; Svoboda, M.; Fischer, C. Application of Forensic Photography for the Detection and Mapping of Egyptian blue and Madder lake in Hellenistic Polychrome Terracottas based on their Photophysical Properties. Dyes and Pigments 2017, 136, 104–115. 48. Pigments Checker v.5; https://chsopensource.org/pigments-checker/ (Accessed Feb 9, 2021). 49. Bacci, M.; Picollo, M. Non-Destructive Spectroscopic Detection of Cobalt(II) in Paintings and Glass. Studies in Conservation 1996, 41, 136–144. 50. Pigments Checker v.5; https://chsopensource.org/pigments-checker/ (Accessed Feb 9, 2021). 51. Cloutis, E.; Norman, L.; Cuddy, M.; Mann, P. Spectral Reflectance (350–2500 nm) Properties of Historic Artists’ Pigments. II. Red–Orange–Yellow Chromates, Jarosites, Organics, Lead(–Tin) Oxides, Sulphides, Nitrites and Antimonates. Journal of Near Infrared Spectroscopy 2016, 24 (2), 119–140. 52. Chen, Y.; Shang, M.; Wua, X.; Feng, S. Hydrothermal Synthesis, Hierarchical Structures and Properties of Blue Pigments SrCuSi4O10 and BaCuSi4O10. Crys. Eng. Comm. 2014, 16, 5418–5423. 53. Kakoulli, I.; Radpour, R.; Lin, Y.; Svoboda, M.; Fischer, C. Application of Forensic Photography for the Detection and Mapping of Egyptian blue and Madder lake in Hellenistic Polychrome Terracottas based on their Photophysical Properties. Dyes and Pigments 2017, 136, 104–115. 54. Zhang, C.; Zhang, N.; Wang, X.; Zhang, L. Novel preparation of an ancient ceramic pigment BaCuSi4O10 and its performance investigation. Materials Research Bulletin 2018, 101, 334–339. 55. Vyhnal, C.; Mahoney, E.; Lin, Y.; Radpour, R.; Wadsworth, H. Pigment Synthesis and Analysis of Color in Art: An Example of Applied Science for High School and College Chemistry Students. J. Chem. Educ. 2020, 97, 1272–1282. 56. Taylor, W. B. S. A Manual of Fresco and Encaustic Painting: Containing Ample Instructions for Executing Works of These Descriptions. With an Historical Memoir of These Arts from the Earliest Periods; Chapman and Hall: London, UK, 1843. https://www.google.com/books/edition/_ /KBYEAAAAYAAJ?hl=en (Accessed Feb 9, 2021). 57. Fresco Painting Chemistry; https://www.sciencelearn.org.nz/resources/488-fresco-paintingchemistry (Accessed Feb 9, 2021). 58. Taylor, W. B. S. A Manual of Fresco and Encaustic Painting: Containing Ample Instructions for Executing Works of These Descriptions. With an Historical Memoir of These Arts from the Earliest Periods; Chapman and Hall: London, UK, 1843. https://www.google.com/books/edition/_ /KBYEAAAAYAAJ?hl=en (Accessed Feb 9, 2021).
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59. Tracing-Pouncing; https://www.youtube.com/watch?v=ZD4RSSueKOs&ab_channel= TizianoLucchesi (Accessed Feb 9, 2021). 60. Daniel Smith Extra Fine Watercolor Tubes and Sets; https://www.dickblick.com/products/ daniel-smith-extra-fine-watercolors/ (Accessed Feb 9, 2021). 61. Schweppe, H.; Winter, J. Madder and Alizarin. In Artists’ Pigments: A Handbook of Their History and Characteristics; FitzHugh, E. , Ed.; National Gallery of Art: Washington, DC, USA, 1997; Vol. 3, pp 109-142. https://www.nga.gov/research/publications/pdf-library/artistspigments-vol-3.html (Accessed Feb 9, 2021). 62. Cornman, M. Cobalt Yellow (Aureolin). In Artists’ Pigments: A Handbook of Their History and Characteristics; Feller, R., Ed.; National Gallery of Art: Washington, DC, USA, 1986; Vol. 1, pp 37-46. https://www.nga.gov/research/publications/pdf-library/artists-pigments-vol-1. html (Accessed Feb 9, 2021). 63. Berrie, B. Prussian Blue. Artists’ Pigments: A Handbook of Their History and Characteristics; FitzHugh, E., Ed.; National Gallery of Art: Washington, DC, 1997; Vol. 3, pp 191-217. https://www.nga.gov/research/publications/pdf-library/artists-pigments-vol-3.html (Accessed Feb 9, 2021). 64. Lühl, L.; Hesse, B.; Mantouvalou, I.; Wilke, M.; Mahlkow, S.; Eleni Aloupi-Siotis, E.; Kanngiesser, B. Confocal XANES and the Attic Black Glaze: The Three-Stage Firing Process through Modern Reproduction. Analytical Chemistry 2014, 86, 6924–6030. 65. Attic Pots and Atomic Particles: Modern Science Looks at Ancient Vases; Getty Conservation Institute panel discussion, May 23rd, 2013. https://www.youtube.com/watch?v= r2rvV5bfpqs&ab_channel=GettyConservationInstitute (Accessed 2021-2-09). 66. Vyhnal, C. Curricular Materials on the Chemistry of Pottery, Including Thermodynamic Calculations for Redox Reactions in the 3-Stage Firing Process of Attic Black- and Red-Figure Wares Produced from the 6th Century BCE; (in preparation). 67. Cultural Heritage Science Open Source, CHSOS. https://www.youtube.com/channel/ UC4oSLjEDZdsci2r8IPEQbsg (accessed 2021-2-09). 68. Cosentino, A. FORS Spectral Database of Historical Pigments in Different Binders. econservation Journal 2014, 2, 54–65. 69. Caggiani, M.; Cosentino, A.; Mangone, A. Pigments Checker version 3.0, A Handy Set for Conservation Scientists: A Free Online Raman Spectra Database. Microchemical Journal 2016, 129, 123–132. 70. Larsen, R.; Coluzzi, N.; Cosentino, A. Free XRF Spectroscopy Database of Pigments Checker. International Journal of Conservation Science 2016, 7 (3), 659–668. 71. DPPMCA Display & Acquisition Software; https://www.amptek.com/software/dpp-mcadisplay-acquisition-software (Accessed Feb 9, 2021). 72. Pigments Checker v.5; https://chsopensource.org/pigments-checker/ (Accessed Feb 9, 2021). 73. Larsen, R.; Coluzzi, N.; Cosentino, A. Free XRF Spectroscopy Database of Pigments Checker. International Journal of Conservation Science 2016, 7 (1), 659–668. 74. Shakespeare portrait “is a fake.” BBC News, 2005-04-22. http://news.bbc.co.uk/2/hi/ entertainment/4471515.stm (Accessed Feb 9, 2021). 75. DPPMCA Display & Acquisition Software; https://www.amptek.com/software/dpp-mcadisplay-acquisition-software (Accessed Feb 9, 2021).
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76. Kakoulli, I.; Fischer, C. An Innovative Noninvasive and Nondestructive Multidisciplinary Approach for the Technical Study of the Byzantine Wall Paintings in the Enkleistra of St. Neophytos in Paphos, Cyprus; https://www.doaks.org/research/byzantine/project-grants/kakoulli-and-fischer2008-2009 (Accessed Feb 9, 2021). 77. Kakoulli, I.; Fischer, C. The Techniques and Materials of the Wall Paintings at the Enkleistra of St. Neophytos (Phase II); https://www.doaks.org/research/byzantine/project-grants/kakoullifischer-2011-2012 (Accessed Feb 9, 2021). 78. Orna, M. Historic Mineral Pigments: Colorful Benchmarks of Ancient Civilizations in Chemical Technology in Antiquity; Rasmussen, S., Ed.; ACS Symposium Series; American Chemical Society: Washington, DC, USA, 2015; Vol. 1211, pp 17-69.
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Chapter 3
Connecting Chemistry and Cultural Heritage: Presenting the Physical Sciences to Non-science Majors and First-Year Students through the Investigation of Works of Art and Archaeological Artifacts Citlalli Rojas Huerta and Maria Parr* Department of Chemistry, Trinity College, 300 Summit Street, Hartford, Connecticut 06106, United States *Email: [email protected].
This chapter describes two courses designed to introduce chemistry to nonscience majors and first-year students using art and archaeology. The first of these, “Archaeological Chemistry”, is a lecture course for non-science majors that fulfills the general education requirement in the natural sciences. Selected case studies from the peer-reviewed literature highlight the utility and application of instrumental methods in the analysis of archaeological samples and students learn about the chemical composition of a variety of archaeological materials and about the analysis of inorganic and organic substances that can be found in archaeological excavations. Hands-on workshops are designed to introduce the students to the scientific method and to allow them to study a specific artifact or material in more detail using methods such as electron microscopy and X-ray fluorescence. The second course, “Bones, Pigments and Native Metals”, is a writing-intensive seminar for first-year students that introduces them to the types of materials found in works of art and archaeological artifacts and to the methods used in the analysis, authentication, and conservation of these materials. Laboratory workshops in the seminar focus on measurement, synthesis, and data analysis. Discussions emphasize the chemical analysis of objects such as paintings, sculpture, documents, coins, and textiles as well as the archaeological information that can be inferred from scientific data. Chemistry topics typically found in introductory chemistry lectures are integrated into discussions in both of these courses in order to give students the necessary knowledge to better understand and appreciate the important role of chemistry in art and archaeology.
© 2021 American Chemical Society
Introduction In January 2021, Archaeology magazine published its list of the top ten archaeological discoveries of 2020 (1). The list included a variety of objects found across several continents that were featured by national and international news outlets, captivating a worldwide audience. One of these discoveries involved the radiocarbon dating of potsherds excavated in Çatalhöyük, through the analysis of fatty acids in food residues found on the pottery fragments. Radiocarbon dating (2), for which Willard F. Libby received the 1960 Nobel Prize in chemistry, has become a crucial tool in archaeology and can be used, along with similar examples, as entry points into a more rigorous exploration of the chemical principles that underpin archaeological science, or archaeometry. In the late 20th and early 21st centuries, the increasing availability of portable instrumentation, coupled with the much smaller amounts of material required for analysis, and the development of nondestructive instrumental methods, have all contributed to the fertile environment wherein archaeometry has flourished. This paper describes two courses that were created for a primarily undergraduate institution (PUI) with non-science majors and first-year students in mind. While both courses introduce scientific literacy, applied chemistry, materials science, and the role of instrumentation in the analysis of art and archaeological artifacts, their structures differ. The common theme is the use of the familiar subjects, art and archaeology, to engage non-science majors and first-year students in the study of chemistry and the physical sciences and to allow students to develop important transferrable skills such as critical thinking, scientific literacy, and data analysis. The structures of the two courses will be presented along with information about the laboratory workshops that were introduced to highlight the role of chemistry in each course.
Archaeological Chemistry: A Lecture Course Designed for Non-science Majors The one-credit course Archaeological Chemistry (CHEM155) is designed to fulfill the general education requirement in the natural sciences for non-science majors at a PUI. This course, first introduced into the curriculum of the Chemistry Department in 2002, is one of a range of nonscience majors courses taught by faculty in the department and is offered in alternate years. The description of the course in the College Bulletin is shown below: CHEM155. Archaeological Chemistry - This course is designed to introduce students to the application of chemical principles to the exploration and explication of archaeological issues. From the identification of ancient trading routes through pottery analysis to the elucidation of human interactions with the environment through investigation of human remains, this course will demonstrate the utility of chemistry and chemical methodologies in archaeological research. The goal of CHEM155 is to introduce scientific literacy and fundamental concepts in chemistry to non-science majors using archaeology as the framework, and to give the students an opportunity to engage in hands-on activities designed to explore the scientific method in a series of laboratory workshops focused on the analysis of archaeological materials. The chemistry topics are selected from the traditional two-semester introductory chemistry sequence (Table 1) and discussions are supplemented with information related to analytical instrumentation and data analysis. Lectures meet for 150 minutes per week during the typical 15-week semester. The enrollment limit is determined by safety considerations related to the available laboratory and workshop spaces. The course has also been adapted for teaching in a more condensed format, consisting of either a five52
or six-week period during the summer term, where classes meet twice per week for a total of 360 minutes per week. The structure of CHEM155 quickly evolved from a traditional lecture format to a more interactive classroom environment, where students have the opportunity to explore a range of topics, either individually or in small groups, and where class participation assignments along with text and literature discussions relate to a specific material, artifact or method of analysis. Course Design, Materials and Topics Several books have been written on the subject of archaeological chemistry (3–14). The American Chemical Society has published a number of volumes on this topic in the Advances in Chemistry Series (5–9) and the ACS Symposium Series (10–12). There are also a number of peerreviewed journals, such as the Journal of Archaeological Science, Archaeometry, Heritage Science, the Journal of Cultural Heritage, and Studies in Conservation, providing a wealth of information for research groups and instructors. While all of these resources are excellent source material for discussion, they are written for a technical audience. The ideal textbook for CHEM155, Lambert’s Traces of the Past (13), is written at a level appropriate for non-science majors, and the organization of the chapters, based on increasingly complex materials, from stone to humans, serves as an outline for the topics that are discussed during the semester. The course uses several case studies taken from Lambert’s text, supplemented by current articles published during the year that the course is offered. An introductory chemistry textbook is also recommended to students who want to access additional information about the chemistry topics covered in the course. In recent years, the physical textbooks have been replaced by recommended electronic books and websites. Malainey’s A Consumer’s Guide to Archaeological Science (14), which is also written for a non-technical audience, is a recent addition to the list of recommended e-books. Students can access the chapters related to the chemistry topics we discuss as well as the sections dealing with archeological materials and those that focus on instrumentation. Supplemental information is taken from journal articles, online encyclopedias and programs selected from the Public Broadcasting Service (PBS), including episodes from NOVA and Secrets of the Dead, as well as others typically available from the streaming video platform, Films on Demand. These programs provide additional opportunities for students to learn more about the process related to the analysis and conservation of archaeological materials, from discovery to data collection and interpretation, and they can form the basis for additional discussions and assignments. Visiting speakers from museums or research universities provide an opportunity for the students to learn about career options in the field and offer a glimpse into the typical working day of an archaeological scientist. In this one-semester lecture course, students learn about the various materials that may be found at an archaeological site and about the crucial role of chemistry and instrumental analysis in the examination of these artifacts. Using broadly-defined material categories, students explore the chemical structures and compositions of a range of inorganic, organic and biological materials and learn about the wide variety of instrumentation available to study elemental, molecular, and isotopic composition, to determine the age or the condition of an object, and to explore the manufacturing processes utilized in its creation. Table 1 summarizes the materials and methods as well as the workshop topics and chemistry concepts that are presented in a typical semester. An important part of the discussion throughout the class focuses on the appropriate choice of instrument based on issues related to accessibility, safety, cost, specificity, sensitivity, and whether a destructive or nondestructive method is available or indeed suitable for the analysis of a particular artifact.
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Table 1. Materials, Chemistry Topics, and Methods in CHEM155 Materials and Topics
Methods of Analysis
Inorganic compounds: stone: marble, quartz, limestone soil: phosphate content, pH levels, iron and manganese content ceramics: faience, terra-cotta, glazes color: pigments and inks glass: modifiers, opacifiers, colorants metals: alloys and native metals Chemistry topics: Bohr model of the atom, atomic orbitals, isotopes and radioactive decay, polyatomic ions, ionic and covalent bonding models, unit cells, acids and bases, pH, causes of color, coordination complexes, crystal field theory, metallurgy
Elemental, isotopic and molecular identification: atomic absorption spectroscopy (AAS) isotopic analyses: 13C/12C, 40K/40Ar, 230Th/238U and 208Pb/206Pb neutron activation analysis (NAA) X-ray methods diffraction, fluorescence and particle-induced X-ray emission (XRD, XRF, PIXE) UV-vis, infrared (IR) and Raman spectroscopies optical emission spectroscopy (OES) thermoluminescence microscopy: electron, metallurgical Other: stratigraphy, typology
Organic compounds: food and drink residues amber and resins insect and vegetable dyes wood flax, cotton Chemistry topics: structures and properties of organic materials, functional groups, terpenoids
Molecular and isotopic identification: isotopic analyses: 15N/14N and 13C/12C IR & Raman spectroscopies chromatographic methods (GC, HPLC) mass spectrometry (MS) nuclear magnetic resonance (NMR) Other: dendrochronology
Biological materials: bone tissue parchment genetic material Chemistry topics: amino acids, DNA and RNA structures, hydroxyapatite, collagen, lipids
Elemental, isotopic and molecular identification: isotopic and elemental analysis amino acid racemization GC-MS analysis DNA analysis Other: dating methods
Workshops: metals and alloys ceramics pigments textiles
Model kits and instrumentation: unit cell structures valence shell electron pair repulsion theory (VSEPR) scanning electron microscopy energy dispersive spectroscopy
The course is divided into four-week modules where students first review the fundamental chemistry topics which will allow them to better understand the role of the physical sciences in archaeology. This is followed by a discussion of several artifacts and instrumental methods which are selected from the textbook and from peer-reviewed journals. The third module focuses on the theory and application of the electron microscope in the analysis of an artifact and the last few weeks of the semester are devoted to data analysis and student presentations of current research in archaeometry. A more detailed discussion of these modules follows below. 54
The first module is devoted to a general introduction of archaeometry, the relevant chemistry concepts, and instrumental analysis (Table 1). In an introduction to the electromagnetic (EM) spectrum and how the different regions in the spectrum can be used in archaeometry, the focus is on the applications of gamma rays, X-rays, ultraviolet, visible, and infrared radiation. We then shift the discussion to the Bohr model of the atom, electronic transitions and the energy changes associated with these transitions. The role of isotopes and radioactive decay in archaeometry is highlighted using radiometric dating examples including radiocarbon, potassium-argon, and uranium-thorium dating. In terms of materials, Lambert’s text includes several examples using chemical formulas and chemical equations, which are used in the lecture to introduce the concept of metallic, ionic and covalent bonding. Students use model kits to learn about the arrangement of cations and anions in ionic compounds and about valence shell electron-pair repulsion (VSEPR) theory for covalent systems. We also discuss acids and bases, with a particular emphasis on pH. These discussions are relevant to the diagenesis of certain materials in interactions with the environment. Information about instrumentation, such as the various components or schematic diagrams of instruments, and many other topics related to archaeological chemistry, are available in Malainey’s text (14) and online encyclopedias such as AccessScience (15). A survey of library databases and online resources required to successfully complete the assignments for the course is also scheduled early in the semester. With so much information available, now primarily online but also in print, it is essential to give students the necessary instruction to allow them to search efficiently for suitable information that they will need to access as the semester progresses. In collaboration with the science and electronic resources librarian, a library session gives students the opportunity to learn about and search the available databases, recommended textbooks and peer-reviewed journals related to archaeological science that each student will use to help them identify a research topic. We highlight the importance of primary sources, how to select peer-reviewed articles, and we also recommend other textbook and online sources that they can access for additional information about the instrumentation. An entire class meeting is devoted to this library session, allowing students time to search for a presentation topic using these library resources. Students are also introduced to the course-specific library research guide, which includes additional resources related to the course, such as online encyclopedias and handbooks, as well as information related to citation formats and guides for giving effective presentations. Students can consult this guide at any point during the semester and are encouraged to make appointments with the librarian and the instructor to review and discuss their library work. All research topics and articles are approved by the instructor well before the due dates for the assignments. On the first day of class, students complete a brief survey and receive a short article featuring a recent archaeological discovery. The survey includes questions about the their interest in the course, their chemistry background and about any artifacts or materials they are interested in exploring in more detail. The answers to these questions are essential for the identification of suitable case studies that we will explore during the semester. Another question is related to the instrumentation methods available for the analysis of artifacts. Although many students are familiar with radiocarbon dating, they are not aware of any other instrumental methods utilized in the analysis of artifacts. The answers to this question have been consistent since the first time the course was offered in 2002. The short articles are written for a general audience and can be found in newspapers, such as The New York Times Science section (16), trade magazines, such as Chemistry World (17), and various online sources such as Science Daily (18). These articles are selected by the instructor a few weeks before the start of the semester and, as a set, cover a range of artifacts. The purpose of this assignment is to introduce the 55
types of materials that we will discuss in more detail during the semester. The students are placed in groups according to the type of materials in the articles and, using these articles as their only source, they answer a series of questions based on the object or material, the method of analysis, if any, and the significant archaeological conclusions. Each group can then discuss the information in the articles with the rest of the class. Group assignments offer opportunities for students to get to know their classmates and to develop team-work and communication skills and are effective in establishing a sense of community early in the semester for students from different academic departments. After the introductory module, we shift our focus to case studies selected from the text and the peer-reviewed literature. This gives students an opportunity to explore different communication styles, such as journalists writing for a general audience (19) or researchers writing for a technical audience (20). We also spend at least one lecture focusing on the different sections that comprise a scientific article, with an emphasis on the materials and methods, tables and figures, and the results and conclusions sections. After this discussion and with the information they received during the library session, students are much more confident in their ability to engage with the scientific literature. During weeks five through eight, we spend at least two lectures discussing a specific material or artifact, with an emphasis on its composition, physical characteristics, and typical methods of analysis (Table 1). We also review sample size requirements and sample preparation methods, as well as the importance of micro-destructive and nondestructive instrumental methods. For example, a reading assignment in Chapter 1 of Lambert’s text related to obsidian, a type of igneous rock also known as volcanic glass, is followed in the lecture by a review of its physical properties, chemical composition, and structure (13). We then discuss the the uses of obsidian and the trade routes that were identified in the Mediterranean region based on elemental analysis of obsidian using XRF, ICP-MS, NAA and SEM-EDS (21). We use a portable X-ray fluorescence analyzer in the lecture to demonstrate this highly efficient and nondestructive analytical method by determining the elemental composition of an obsidian replica arrowhead (Figure 1).
Figure 1. Elemental analysis of obsidian showing peaks for iron, rubidium, zirconium and zinc obtained with a Tracer III-V portable X-ray fluorescence analyzer on loan from Bruker Handheld LLC. Courtesy of Dr. Bruce Kaiser.
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The peer-reviewed articles highlight recent developments in instrumentation as applied to archaeological materials, ensuring that the content of the course reflects the latest advances in the field, such as the application of laser methods based on light detection and ranging (LiDAR) to discover lost cities (22) and 3D mass digitization methods used to assist with conservation decisions or to recreate damaged or fragile artifacts, such as bone fragments or Egyptian busts (23). These articles also help to emphasize the multidisciplinary nature of archaeometry. The SEM-EDS workshop, the focus of the third module, gives the students the opportunity to study a method of analysis in detail. This workshop was developed by the instructor in collaboration with the electron microscopy facility on campus using artifacts supplied by the state archaeologist and a faculty member in the Classics Department. Since 2002, students have collected micrographs and elemental analysis data for a range of artifacts including beads, tools, and other metal artifacts (24) as well as coins and potsherds. For example, Figure 2 shows a potsherd borrowed from the Classics Department for analysis in CHEM155. Sample preparation involved cutting a small piece, which was subsequently washed with methanol, polished and coated with carbon prior to analysis. The cross-sectional analysis allowed the students to collect micrographs (Figure 2) and elemental analysis data (Figure 3) of the aluminosilicate matrix, the inclusions, and the pigment found on the surface of the sample. During the last four weeks of the course, we review and discuss the data collected during the SEM-EDS workshop and each student presents a case study to the class from the recent peer-reviewed literature that they selected and researched over the course of the semester.
Figure 2. Potsherd analyzed by SEM-EDS (left) and SEM micrograph of cross-section (right): a = matrix; b = inclusion; c= pigment; potsherd dimensions: 7.3 cm (l) x 7.5 cm (h) x 0.4 cm (w). At the end of the course, students are able to appreciate more deeply the role of chemistry and other physical sciences in archaeology. They can recognize the importance of isotopes that can be used not only for dating purposes, but also to extract information related to diet, the environment, and migration patterns (25). Students can understand the structures and compositions of archaeological materials ranging from minerals, pigments, and ceramics, to glass (26), DNA (27), and metals (28). They can also identify the chemical composition of some of the pigments and dyes used in antiquity, they can understand the importance of metallurgy, and also appreciate the complexity of extracting and analyzing ancient DNA. The workshops allow students to determine the elemental composition and morphological characteristics of a variety of artifacts by SEM-EDS.
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Figure 3. EDS data of the aluminosilicate matrix, a, (upper); the inclusion, b, (middle); and the pigment, c, (lower) of potsherd shown in Figure 2. Horizontal axis: energy in keV; vertical axis: intensity in counts. Laboratory Workshops The SEM-EDS workshop designed for CHEM155 has been described elsewhere (29). We have also developed individual research projects for undergraduates who were students in the course (40%) or for science majors who developed an interest in exploring the intersection between art, archaeology and chemistry (60%). Research students typically spend several semesters working on a project and gain experience in several areas, such as archaeology, materials science, chemistry, and history. Upon completion of the project, students write a report and also present the results of their research at the Science Symposium on campus or at regional or national meetings of the American Chemical Society. 58
Several dry labs using commercially available kits sold by Lab-Aids (30), illustrating the process of dendrochronology, and the identification of basic crystal shapes, are integrated into the lecture and can typically be completed within one or two lecture sessions. For example, during a discussion of dating methods in archaeology, simulated core samples are used to illustrate dendrochronology, an absolute method which relies on the presence of tree rings. We discuss new vocabulary related to ring growth using a cross-section view of a tree trunk and review the elemental composition and structure of cellulose. The article selected to supplement this dry lab describes the dendrochronological study of a panel painting believed to be a portrait of Shakespeare (31). A crystal structure kit is the starting point for the discussion of minerals, where students probe the structure and composition of ionic compounds such as calcite, and learn about crystal shapes and symmetry using pre-cut patterns. Other kits, such as the Solid-State Model Kit available from the Institute for Chemical Education (32) allow students to build models of unit cells of ionic compounds and to learn about their packing arrangements and stoichiometry. The kit includes templates and easy-to-follow instructions for a series of compounds. A molecular model kit for general chemistry is utilized to illustrate VSEPR theory. Both the ionic lattice kit and the molecular model kit are borrowed from the introductory chemistry laboratory. Assessment and Student Feedback A mix of high stakes assessments such as quizzes, presentations, laboratory workshops and problem sets, as well as low stakes assignments, such as class participation and group worksheets, are included in the CHEM155 syllabus in order to reinforce the concepts that are discussed during the semester and to assess mastery of the material. The PBS programs (33) and selected websites (34–36) offer additional opportunities for lecture discussions and assignments, and are particularly useful in the illustration of analytical techniques such as radiocarbon dating and Raman microprobe analysis. During the last week of classes, students are asked to complete two surveys in addition to the course evaluation form required by the college. One survey, inspired by SALG (37), helps the instructor to identify possible changes in attitude by asking students about gains that they have made as a result of taking the course. In responding to the questions related to their confidence in understanding the course material, their comfort level with the science content, making connections with other knowledge, and applying the information in other situations, over 90% of the students report making either “moderate gains” or “great gains”. In the second survey, students are asked about their initial perception of the role of chemistry in archaeology and whether this has changed as a result of taking the course. Students universally acknowledge their surprise at the variety of instruments available for analysis and the amount of work involved during the sample collection and preparation stages, as well as the data collection and interpretation steps required during a typical archaeometry project. They also have a deeper appreciation and understanding of the importance of collaborative work between chemists and archaeologists, and consider chemistry to be an “essential” component. Another way to gauge interest is based on notes or emails sent by students to the instructor, sometimes long after the course has ended, where they share articles which they think might be useful in future classes, or information about a museum visit during a semester abroad relating to the topics that were presented in the course. Student feedback has consistently shown that the hands-on activities during the lecture, and the SEM-EDS workshop in particular, are highlights of the course. Typical comments are included below: “That lab was very interesting. Just to see it in action was very ‘cool’.” 59
“I thought that the SEM Workshop was very interesting. It gives a completely different perspective and understanding of the theoretical part. It is also impressive to see how much data we are able to obtain.” “I thought the SEM workshop was really great. While we’ve learned about it in class it was very helpful to actually see the microscope in action. Some things that I had been unclear on were sorted out during the workshop. The workshop clarified how exactly the microscope worked by seeing it.”
Bones, Pigments and Native Metals: A Scientist’s Guide to Art and Archaeology: A Seminar Course Designed for First-Year Students This seminar is a writing intensive (WI) course designed to introduce first-year students to the role of several disciplines, primarily chemistry, in the study of works of art and of archaeological artifacts. Discussion topics include chemistry, materials science, instrumental analysis, and conservation methods, as well as art historical and archaeological information, in order to understand the process of creation and the ethical issues related to the conservation or preservation of these objects for future generations. Students submit several formal and informal writing assignments related to this multidisciplinary area of research, which along with laboratory workshops, serve to illustrate and reinforce essential concepts commonly encountered in first year chemistry courses (Table 2). Having this experience early in their college career may encourage some students to choose a major in the sciences and the transferrable skills they develop during the seminar are useful as they progress through college, irrespective of their chosen major. The description of the course found in the College Bulletin is shown below: FYSM161. Bones, Pigments and Native Metals: A Scientist’s Guide to Art and Archaeology - This seminar will explore the importance of the physical sciences in art and archaeology. In particular, we will examine how the discovery and development of materials such as ceramics, metal alloys and pigments influenced artists and how they utilized these materials to create works of art. We will also consider a number of case studies where scientific analysis played a crucial role in the authentication or conservation of objects. Laboratory workshops and guest speakers from local museums and conservation laboratories will supplement the lectures, readings and discussions. A weekend visit to a local art museum will also be scheduled during the semester. FYR3. The first year seminar serves several purposes, but the primary focus of the course is the WI component. Although the number of class meetings and the goals of this seminar are similar to those described for CHEM155, students in FYSM161 achieve these goals through a series of writing assignments, both formal and informal, and are also expected to prepare formal presentations on selected topics. In addition, this seminar serves not only as an introduction to archaeometry, and art analysis and conservation, but it is broader in scope than CHEM155, because the instructor also serves as an adviser to the students during four semesters. Both the instructor and a student mentor, who is typically a junior or senior, assist the students with their transition to college life and to life in a new city. In order to introduce the students to the community, a visit to a local museum is one of the more important off-campus events that are planned for the group. Visiting speakers from museum conservation labs in the area or who are active in the field of archaeological science, as well as presentations by the Archaeological Institute of America on campus, round out the programming scheduled for the seminar. The mentor, who attends every seminar meeting, also provides support 60
throughout the semester with academic and extra-curricular activities, and is also available to assist during the laboratory sessions. Upon successful completion of the seminar, students have fulfilled two of the general education requirements as indicated by the FYR3 designation: “Writing Emphasis Part 1” and the “Natural Sciences General Education Distribution”. Course Design, Materials and Topics Several books, along with selected case studies related to the development and application of pigments and dyes, the authenticity of documents, the analysis of human remains, and objects comprised of native metals, and alloys are covered during the semester (Table 2). The assignments in FYSM161 consist of several papers and presentations as well as laboratory reports associated with the workshops. Given that the course is expected to serve as an introduction to college-level writing, tours of the library and a library session specifically geared toward the seminar topics are scheduled early in the semester. Databases such as JSTOR and Artstor as well as online encyclopedias such as McGraw Hill’s AccessScience (15) are presented along with selected texts (38–41) and peer-reviewed sources covering the analysis and conservation of various objects and artifacts (42–44). Students in the seminar begin the semester reading Philip Ball’s book, Bright Earth: Art and the Invention of Color, which explores the history of pigments and dyes from a chemist’s perspective, and allows students to understand the origins and compositions of the many colors available to artists (45). Starting with examples of Paleolithic art from around the world, primarily caves designated as World Heritage Sites by UNESCO, we focus on the composition and structure of the four common pigments found in the hand stencils and figurative paintings - red and yellow ochres (iron oxides), white (calcium carbonate, kaolin or calcite), and black (charcoal or manganese oxide) (45–49). These examples present an excellent opportunity to discuss the role of radiometric dating, such as radiocarbon, and uranium-thorium methods, used to estimate the approximate age of some of these drawings. We connect these concepts to a review of isotopes and radioactive decay that relate to absolute dating methods, and conclude this discussion with a review of the current literature. The most recent seminar featured a paper reporting 230Th/238U dates obtained for samples found in Southern Europe that pushes back the dates of some of the earliest cave art by about 20,000 years, implicating Neanderthals as the likely artists (47). We then discuss the introduction of additional pigments through time, such as Egyptian blue, the use of pigments and dyes during the medieval period, the renaissance, and the synthetic pigments and dyes produced during the 19th century (45). A discussion of the visible region of the EM spectrum and the causes of color in pigments and dyes, in addition to a review of the Bohr model of the atom, d-orbitals, electronic transitions, and charge transfer processes for inorganic pigments, and the role of chromophores and auxochromes in organic dyes, are the chemistry topics presented at this point in the semester. Students also learn about common binders used to create paints and the processes necessary for the creation of frescoes, panel paintings, oil paintings and pastels. We also discuss the analysis of paint cross-sections in order to identify the various layers that comprise a typical painting, for example, the varnish, pigments and dyes, binders, ground, and possible degradation products of these materials, by SEM-EDS, XRD, FTIR, and SIMS (50). We then shift the seminar discussion to methods of analysis. A case study from the collection of the National Center for Case Study Teaching in Science (NCCSTS) is essential in helping students understand the role of different analytical tools utilized in the analysis of a painting in a private collection (51). There are several methods presented in this article and we use this as an opportunity to learn about the roles of X-ray, FTIR, and UV methods of analysis in detail. An interactive website, 61
WebExhibits.org, which describes the results of X-ray and infrared analyses of Feast of the Gods, a painting housed at the National Gallery of Art in Washington, D.C., is also an excellent supplement to our discussions (52). This website also includes a useful pigment timeline, comprising the history of several colors, as well as synthetic protocols and methods of identification. After completing all the readings, problem sets, and class participation assignments, as well as the NCCSTS worksheet, students visit an art museum in order to select an individual object for their first formal writing project, in which they are expected to report on the technical art history and possible conservation methods related to the object that they select. In addition to the research paper, a formal presentation is also made to the class, allowing each student to practice their presentation skills. Table 2. Materials and Methods in FYSM161 Materials
Methods
Art & archaeology: Ball - Bright Earth pigments and dyes color theory painting materials and methods illuminated manuscripts conservation
Elemental and molecular analyses: Malainey - A Consumer’s Guide to Archaeological Science X-ray methods - diffraction (XRD) portable X-ray methods - fluorescence (pXRF) UV-vis, IR and Raman spectroscopies nuclear magnetic resonance (NMR) scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS)
Ink & parchment: Seaver - Maps, Myths & Men iron gall ink anatase rubrication parchment
Molecular and elemental identification: peer-reviewed articles particle-induced X-ray emission (PIXE) electron microscopy (SEM and TEM) Raman microprobe spectroscopy radiocarbon dating
Human remains: Chatters - Ancient Encounters bone soil genetic material
Dating, isotopic, and molecular identification: Malainey - A Consumer’s Guide to Archaeological Science radiocarbon dating/accelerator mass spectrometry (AMS) isotopic analysis (carbon, nitrogen) DNA analysis computed tomography (CT) scans
Native metals: beads, coins native copper, brass, bronze silver gold
Analysis methods: peer-reviewed articles metallography pXRF SEM-EDS
Laboratory workshops: metals alloys pigments
Measurements, synthesis and microscopy: density measurements - pycnometer synthesis - chemical reactions and percent yield; binders pigment identification - polarized light microscopy (PLM)
The discovery of the remains of the Kennewick Man in the last decade of the 20th century, as described by James Chatters in his book Ancient Encounters: Kennewick Man and the First Americans (53), is an excellent subject for the students to discuss and debate the role of scientific analysis as applied to human remains. The debate centers around the initial radiocarbon, isotopic and DNA analyses of the remains of the Kennewick Man, the traditional practices of the Native American 62
groups in the region, the role of the Native American Graves Protection and Repatriation Act (NAGPRA), and the importance of this discovery to the archaeological record of North America. Teams of students research this case from the perspective of different groups: Native Americans in the region where the bones were discovered, the government who enacted NAGPRA in 1990 and the U.S. Army Corps of Engineers who managed the land, as well as the scientists who argued to keep the remains available for scientific study. The question under consideration by each team is: “Who has the legitimate right to claim Kennewick Man’s remains?”. Each member of the team prepares an opening statement. This debate-style assignment typically leads to lively discussions that take place over several class meetings, and include opening statements, rebuttals and closing arguments. Students need to understand the science involved in order to discuss the ethical and legal ramifications in a meaningful way. At the conclusion of the discussion, all students vote and, if they were persuaded to change their minds during the process, to write about which argument was responsible for this change. The analytical methods that are presented by the team of scientists include radiocarbon dating, carbon and nitrogen isotope analysis, yielding information about diet, in addition to DNA analysis, that can provide proof of cultural affiliation. This case highlights a number of ethical issues related to radiocarbon dating, a process requiring the removal and destruction of a small piece of bone in order to establish the approximate age, and also the handling of the remains during storage in a museum setting (54). These points relate to previous discussions in the course focused on the importance of sample size requirements and the availability of destructive and nondestructive analytical methods. Additional discussions of the ethical dimensions in archaeology, including issues around stewardship and current best practices, are facilitated by several valuable resources (55–58) and demonstrate to the students that there are important guidelines to follow when working with archaeological materials. The Kennewick Man case was resolved in 2015, in part due to advances in DNA technology that revealed the cultural affiliation between the remains of the Kennewick Man and the Native American tribes in the region (59), as is required by NAGPRA. The controversy surrounding the authenticity of the Vinland Map is explored using Kirsten Seaver’s book Maps, Myths and Men: The Story of the Vinland Map (60), along with several articles taken from the technical literature (61–65). Students work in small groups, each focusing on a specific method of analysis related either to the ink or the parchment, such as Raman microprobe spectroscopy, electron microscopy, radiocarbon dating, particle-induced X-ray emission and X-ray diffraction. Each group also reviews another aspect of the multidisciplinary research connected to the map, such as the L’Anse aux Meadows archaeological site, Norse history, provenance, associated manuscripts, handwriting and cartography. The groups debate the pros and cons of each instrumental method with respect to sample size requirements, and discuss data collection and interpretation. Once all teams have presented their research on the map, students are asked to vote on whether they believe the map is an authentic document based on the scientific analyses and the historical information. An excellent account of this map is available from the broadcast NOVA: The Viking Deception (66) which illustrates some of the methods of analysis such as Raman microprobe spectroscopy, PIXE and transmission electron microscopy. For metals, we use case studies found in the literature (28, 67–71) and Malainey’s text (14). These sources are supplemented by a discussion of the SEM-EDS analysis of coins and beads that were originally carried out on campus by research assistants or during the CHEM155 workshop. For example, Figure 4 shows a Roman coin that was analyzed in order to learn about its composition and possible corrosion products.
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Figure 4. Urbs Roma coin - obverse (left) and reverse (right); scale: 1 division = 1 mm. Figure 5 shows the EDS spectrum of a region relatively free of corrosion, corresponding to the helmet area on the figure on the left. A cross-sectional analysis revealed high concentrations of copper, lead and tin in the bulk area, elements commonly found in bronze, while the analysis of the surface revealed the presence of chlorine, calcium, phosphorus and silicon, typical environmental corrosion products. In another example, students learn about the elemental composition of a set of copper beads found in an archaeological site near the Connecticut River (24). We also discuss metallurgical processes and metallography and use portable XRF methods to learn about the elemental composition of other artifacts comprised of metals and alloys.
Figure 5. EDS spectrum of helmet area (Figure 4, left) showing the presence of copper, tin and lead, an alloy composition typical of bronze. At the end of the seminar, students have had the opportunity to discover, discuss and write about a variety of objects related to art and archaeology, with particular attention focused on the scientific description of their properties, structures and compositions. They have also explored the role of instrumentation in the analysis of a range of materials and studied issues related to ethics and conservation. In order to do this, they have learned important chemistry concepts as outlined in Table 2. From identifying and accessing suitable library resources to writing and revising multiple drafts, the communication skills that they develop during the semester serve as a foundation they
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can continue to build upon as they progress through college. The inclusion of laboratory workshops serves to strengthen these concepts through active learning. Laboratory Workshops Lab experiences for students in the seminar are adapted from a Chemistry in Art Workshop held at Millersville University of Pennsylvania. This workshop is sponsored by the Center for Workshops in the Chemical Sciences (CWCS) and funded through the NSF CCLI National Dissemination Grant (DUECCLI0089417) (72). The lab experiments are designed to illustrate scientific principles such as measurement, pigment synthesis and analysis. A discussion of technical writing during these workshops is included to support the WI designation, and students are expected to write a short lab report for each experiment. We start preparing for these workshops at least one week in advance, with a safety lecture and a tour of the laboratory. We review the experimental protocols first in the lecture and again during the pre-lab sessions. Students work in small groups and rotate through a series of stations set up with all of the necessary glassware, reagents and equipment. The workshops comprise the synthesis of two inorganic pigments, malachite green, a basic copper(II) carbonate compound, and school bus yellow, zinc(II) chromate; the identification of metals and alloys using a pycnometer; and the analysis of pigment particles using PLM. The synthesis experiments give the students an opportunity to review chemical formulas of inorganic compounds, they practice writing chemical equations, and work on calculations related to theoretical and percent yields. In the density experiment, students collect data using a pycnometer and calculate the density of a metal disc or a coin in order to identify the metal or alloy. Multiple measurements are taken, allowing for a discussion of accuracy, precision, and percent error. Students learn about PLM by viewing several pigment particles and describing their size, shape, color, and isotropic or anisotropic optical behavior. Each student is assigned an unknown to identify using this technique. Group 1 cations in solution are characterized by flame emission in an experiment we use to illustrate spectroscopic characterization. The department houses an instrument center used for research and teaching purposes. Having reviewed a number of schematic diagrams for a range of instruments during seminar discussions and presentations, a tour of the instrument center is designed to give students an opportunity to view various instruments and to learn about sample requirements. Diffractograms and spectra related to art and archaeological materials, either taken on site or from the literature, are also included in this tour. Highlights include an X-ray powder diffractometer, spectroscopic methods, such as FTIR, Raman, and multinuclear NMR, and chromatographic methods including GC-MS and HPLC. Assessment and Student Feedback The final grade in FYSM161 is based on weekly writing assignments, two presentations, several problem sets, individual and group participation assignments, two quizzes, and the laboratory workshops. Group exercises covered during class focus on vocabulary and concepts in peer-reviewed articles as well as calculations related to lecture and laboratory workshops. Chemistry assignments relate to fundamental topics, such as the nature of the atom, simple ionic and covalent compounds, the electromagnetic spectrum, electronic transitions, metals and alloys and spectroscopic analysis. Assignments and quizzes cover topics from the readings, guest lectures and class discussions. A similar survey adapted from SALG is used in this course (37). Over 95% of the students report making either “moderate gains” or “great gains” with respect to their confidence in understanding the material, their comfort level with the science content, connecting key seminar ideas with other knowledge, and applying the information in other situations. Some students found the course to 65
be a “great review of chemistry and it helps me to appreciate art more” while others indicate that “the material is more interesting than I thought it would be. We have covered a wide range of topics which is nice”, and “I did not realize how important it was to learn about methods of analysis for archaeology and more importantly how much of an interdisciplinary science it is”.
Conclusion Art and archaeology are topics with broad appeal which can be used to encourage students to engage with the sciences using examples that have significant chemical associations, and allow non-science majors to become familiar with important chemical concepts. Several goals, such as increasing scientific literacy, improving oral and written communication skills, and highlighting the importance of chemistry in a multidisciplinary context, have been achieved in these courses. The laboratory workshops and research projects provide an interactive and practical environment in which students can explore important chemistry concepts, and can be adapted to the materials and equipment available at many PUIs.
Acknowledgments M. P. is fortunate to have met so many wonderful mentors and collaborators during the development and implementation of CHEM155 and FYSM161. Professor Martha Risser, from the Classics Department at Trinity College, generously shared her expertise in ancient pottery and we appreciate the loan of potsherds for analysis. The loan of archaeological materials was also made possible by Dr. Nicholas Bellantoni, the State Archaeologist, now emeritus, and the staff at the Office of the State Archaeologist at the University of Connecticut. Ann Lehman, the Director of the Electron Microscopy facility, was instrumental in the development of the SEM-EDS workshops for CHEM155 and an essential member of the research team. A Zeiss EVO LS-15 scanning electron microscope was purchased with funds from the NSF-MRI Division of Materials Research (Award No. 1039588). We thank Jennifer van Sickle, the Science and Electronic Resources Librarian, for organizing the library sessions and for working with our students and research assistants. M. P. especially thanks the faculty and staff at the MIT Summer Institute in Materials Science and Material Culture (funded by the NSF Division of Materials Research) and the Chemistry in Art Workshop held at Millersville University of Pennsylvania (sponsored by the CWCS and funded through the NSF CCLI National Dissemination Grant: DUECCLI0089417). A number of the experiments presented at these workshops were adapted for use in the two courses described in this chapter.
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Chapter 4
Using Examples from Art and Archaeology to Demonstrate the Chemistry of Materials in a General Education Course Jennifer E. Mihalick* Department of Chemistry, University of Wisconsin Oshkosh, 800 Algoma Boulevard, Oshkosh, Wisconsin 54901, United States *Email: [email protected].
“Introduction to the Chemistry of Materials,” a general education lab science course, focuses on the chemistry behind materials that society depends on: metals, polymers, and ceramics. This chapter presents the design of the course, and offers details of specific ways that examples from art and archaeology were used in the lectures, reading assignments, and laboratories. Learning activities based on art and archaeology gave students practice with two course-level learning objectives, “describe interrelationships among structure & composition, physical & chemical properties, processing, and performance for each class of material”, and “explain how the history of civilizations is tied to the development of materials and the sustainability of their practices”. Since the general education program required that students acquire knowledge about sustainability and its applications, this course used a sustainability perspective to analyze how the life cycles of materials affect society and the environment. This chapter includes specific objectives for each type of material, references to reading assignments, and samples of questions used to assess student learning. References for all of the laboratory activities are provided, as well as detailed information about the implementation of labs involving analysis of art objects, demonstrations of intermolecular forces with artists’ materials, and syntheses of artists’ materials.
Introduction Materials surround us. A course that teaches the chemistry behind the materials that our society depends on prepares students to spend their lives making, selling, and consuming them (1). “Introduction to the Chemistry of Materials,” a general education lab science course aimed at students who are not science majors, was the result of a collaboration between an artist and a chemist. Because our general education program required that all students take two semesters of science with lab, I was particularly interested in attracting art majors to a chemistry course so they could learn to use chemicals safely and effectively. © 2021 American Chemical Society
In this chapter I present the course design, then present examples from art and archaeology that were incorporated into labs, lectures, and homework assignments. Learning activities and assessments were aligned with two course-level learning objectives. The first objective, “describe interrelationships among structure & composition, physical & chemical properties, processing, and performance for each class of material”, was often found in introductory materials science courses (2). The second objective, “explain how the history of civilizations is tied to the development of materials and the sustainability of their practices”, aligned with a signature question of the university’s general education program, “how do people understand and create a more sustainable world?” and emphasized the relevance of chemistry in a liberal arts education.
Chemistry of Materials Course Design Initially I worked with Kathleen Donnelly, a costume designer who is now Professor Emerita of Theatre, to prepare laboratory activities based on our overlapping interests in fabrics and dyes (3). We found many ideas for labs relating chemistry and art in Journal of Chemical Education, which led us to Mary Virginia Orna’s book (4). From that starting point I developed additional laboratories, and lectures, to teach about metals, polymers and ceramics. I participated in a materials science workshop (5) and gathered background information from materials science books (6–11). In order to learn about advances in materials science I monitored news sources including Chemical & Engineering News, Science News, and The New York Times. I compiled links to news articles and educational websites on a publicly available course webpage (12). The webpage also has links to manufacturers, trade organizations, and government reports. Museum websites provide images of art and archaeological artifacts, and information about the historical development of materials. After teaching the course twice with an out-of-print textbook (8) I wrote my own course manual (13). Chemical principles are explained when needed to understand the properties of each type of material. I have taught with this course manual five times, and regularly shared chapters with other educators who were interested in adding materials chemistry to their courses. CWCS Chemistry in Art workshops led by Patricia Hill and Deberah Simon (14) gave me more training in art-related laboratory activities, several of which I adapted for this course (15). The four credit course was scheduled for three hours of lecture, and a two hour ten minute lab period each week, over a fourteen week semester. The lab had space for 24 students. There was usually enough student interest to offer two sections of lab, so there were up to 48 students in the lecture. Table 1. Topics Covered in Lectures, and Related Lab Activities unit
chapters
hours
lab activities
1
classification of materials structure of solids metals, alloys
3 3 6
physical properties (density, resistance) properties of crystals (1) modification of metal properties (16, 17)
2
structure of polymers polymerization reactions applications of polymers light and color
4 3 3 2
fiber identification (18, 19) building polymer models polyester synthesis (20) paper chromatography (21) effect of metals on fabric dyeing (3) preparation of pigment and paint (22, 15)
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Table 1. (Continued). Topics Covered in Lectures, and Related Lab Activities unit
3
chapters pottery glass construction materials semiconductors advanced materials
hours 2 3 2 3 2
lab activities identification of metals in ceramics (15) preparation of glass (23, 24, 15) preparation of concrete (25) student presentations
I divided the semester into three units, each featuring one of the major classes of materials (metals, polymers, and ceramics). Table 1 displays the chapters in the course manual (13) that were covered in each unit, and the hours of lecture scheduled for each chapter. Each week students read a chapter, and looked at articles or websites linked to the course webpage (12). In order to evaluate the sustainability of materials, students needed to consider their complete life cycles, starting with natural resources and ending with their post-consumer fates, so I added a supplementary text, Garbology (26), which provides qualitative and quantitative information about unwanted materials that are put in the trash. During lectures I asked students to consider the properties of samples in the classroom, such as chairs, notebook paper, and coffee mugs, then displayed images of other materials from a variety of sources such as websites linked to the course webpage (12). I introduced chemical concepts such as atomic structure, periodic properties, bonding, and reactivity in the context of structure & composition, physical & chemical properties, processing, and performance of each class of material. In addition to traditional lectures, I used lecture time for in-class activities such as case studies, videos, and exercises to develop chemistry skills (such as drawing Lewis structures). Some student work was collected and graded; more often, students compared answers and corrected their own work. At least one in-class activity was offered per week. Table 1 also lists lab activities selected to support the lecture topics. During the lab period students observed the physical and chemical properties of materials; saw how properties were affected by changes in structure, composition, or processing; and tested the performance of materials. Some reactions were not complete after two hours, so samples were stored until the next lab period. Prelab assignments asked students to connect what they had learned in lecture to what they would do in lab. Student also turned in lab notes with their observations and analyses; these were graded pass/fail. During the subsequent lecture I discussed important conclusions, and responded to any misconceptions revealed by lab notes, so students would be prepared to answer questions about the labs on exams. During the last lab of each semester I collected anonymous surveys about the lab experience. I asked students to select their most favorite and least favorite lab, and to explain their reasons. More than 75% of students selected labs that involved the creation of materials (polyester, pigment, glass, concrete) as favorites. Table 2 shows an example of learning objectives matched to a chapter. The course-level objective “describe interrelationships among structure & composition, physical & chemical properties, processing, and performance” was expanded into specific objectives for the chapter on pottery. The objectives “list sources of raw materials” and “describe stages in the evolution of porcelain from dried clay” also aligned with the course-level objective “explain how the history of civilizations is tied to the development of materials and the sustainability of their practices”. The homework assignment for this chapter, which asked students to use information from the readings to address the objectives, is displayed in Figure 1. Homework was not collected; students compared their work to an answer key. 73
Table 2. Specific Learning Objectives for Pottery course objectives
specific objectives
composition & structure
list sources of raw materials know typical chemical compositions know what chemicals add color to pottery compare covalent and ionic bonding
properties
explain brittleness of ceramics in terms of bonding predict the effects of compression and tension describe mechanisms for heat conduction
processing
describe stages in the evolution of porcelain from dried clay predict effects of oxygen content in kiln atmosphere
performance
explain how porosity variations in pottery determine uses compare ceramics, metals, and polymers in applications
Figure 1. Homework assignment for the chapter on pottery. Each week ended with a short quiz on the homework, or a review period and an exam, containing of a mixture of multiple choice and short answer questions which were similar to questions on the homework. Research papers (on a metal, a polymer, and an advanced material) based on articles from Chemical & Engineering News, and an oral presentation, gave students more opportunities to describe structure & composition, physical & chemical properties, processing, and performance of materials. 74
The grading scheme from the most recent offering of the course appears in Table 3. Because Introduction to the Chemistry of Materials was offered as a first year experience course, students were required to document participation in selected campus events. Table 3. Course Grading Scheme assignment
points
percent of total
exams (3) laboratory work quizzes (best 10) papers (3) & presentation in-class activities (up to 13) campus events
300 120 80 54 26 20
50.0% 20.0 13.3 9.0 4.3 3.3
total
600
Addressing Course Objectives using Art and Archaeology While it was convenient to start a discussion of materials with clothing, desks, and coffee mugs – familiar samples that students observe on a daily basis – I found that shifting the discussion to rare objects such as ancient potsherds or celebrated Renaissance paintings was a great way to engage student interest. Who knew that household appliances and King Tut’s mask both have enamel coatings? The inclusion of antique and artistic objects among the examples of metals, polymers, and ceramics gave students specific, memorable examples to connect to abstract concepts. The study of ancient artifacts supported both of the course-level learning objectives. Each section of the course considered simple materials that were produced by ancient civilizations. Describing connections among properties, composition, and structure was often easier for ancient samples that underwent limited processing. Lectures on the historical development of materials highlighted new properties and improved performance that were achieved as societies gained access to natural resources, and developed new technologies for materials processing. Table 4 lists examples of historic interest that could be studied via links in the course webpage (12). Table 4. Objects of Historic Significance metals Science Museum artifacts iron age smelting, forging samurai sword
polymers early paper making ancient dyes and pigments Bakelite
ceramics neolithic dig site Athenian vases the Lycurgus cup
Development of Metals and Alloys A specific learning objective for the metals chapter was “recall historic eras labeled by materials (in chronological order)”. I did not intend for students to memorize the dates of the Copper, Bronze, and Iron ages; instead, I expected them to compare the complexities of the processing methods that were required to create useful objects from these materials. Additional objectives focused on the evolution of steel, “distinguish the chemical compositions of wrought iron and cast iron” and “describe processes used in steel manufacturing (ancient and modern)”. Homework assignments about metals and alloys asked students to 75
• List the processing methods that were applied to copper in ancient times. • Look at the metal examples from the Science Museum. Which metals have been used the longest? • Compare the composition and properties of cast iron, wrought iron, and steel. • Why does a high carbon content make iron more brittle? • List three ways to shape steel objects. Traces of the Past (27), written by an archaeological chemist, was a valuable resource. The book contains chapters for many types of materials, with information about artifacts from different geographical locations and time periods. The descriptions are supported by images and chemical analyses. In lecture I showed micrographs of ancient and modern copper samples [(27), pp. 169171] that had experienced different processing methods (cold working, annealing, casting), and asked students to compare the structures of the samples. We used case studies to analyze the life cycles of materials from a sustainability perspective. After an introduction to chemical reactions of metals, I distributed copies of an article about lead pollution in the Andes that 21st century scientists traced to colonial-era silver mining (28). The students worked in small groups to list impacts of silver mining on the environment; on the Spanish and Peruvian societies; and on the Spanish and Peruvian economies. Student learning was assessed with quiz and exam questions aligned with the objectives. A few examples appear in Figure 2.
Figure 2. Assessment questions for metals and alloys. Development of Polymers, Dyes, and Paints Ancient samples of polymers are rare. Although we discussed historical developments in textiles and paper, most of the representative examples were of modern fashions rather than archaeological artifacts. A homework assignment asked students to “list the important milestones of synthetic polymer development”. The historically significant Apollo spacesuits were used to illustrate the benefits and drawbacks of combining materials (29). Polymer-based art objects served as important examples for the chapter on dyes and paints. Specific objectives for this chapter included “describe ancient and modern methods used to prepare paints and dyes” and “identify problems associated with aging of dyed and painted objects”. The related homework questions were
76
• Name three pigments and three dyes used by ancient civilizations; for each one give its source and color. • What chemicals were used in the “Turkey Red” dye process? List some environmental and societal impacts of the industrial application of the process (30). A case study of an artistic dyeing process offered an opportunity to examine how the history of a civilization is tied to the development of materials and the sustainability of their practices. I shared excerpts from an article about kimono producers on Amami Oshima who were trying to maintain techniques that their ancestors developed hundreds of years ago (31). We classified the process as environmentally sustainable, in contrast to the Turkey red process, but identified problems with economic and social sustainability. Examples of true/false questions used to assess students on the objectives from this unit appear in Figure 3.
Figure 3. Assessment questions for polymers, dyes, and paints. Development of Ceramics The specific objectives for the pottery chapter, and the homework assignment, appear in Table 2. The assignment asked students to look at images from a neolithic site excavated by the Field Museum (32), showing objects made of stone, bone, shell, and pottery. An objective related to historical development was “describe stages in evolution of porcelain from dried clay”. This was illustrated with terra cotta soldiers of Xian, earthenware from Persia, majolica from southern Europe, and stoneware and porcelain from China. One of the most famous achievements of artists in ancient Athens was the production of black and red figure pottery. The black and red colors were both created by an iron oxide glaze, with the iron in different oxidation states. Potters who lived more than 2500 years ago learned to create figures containing both red and black iron oxide by applying protective glazes, and altering the oxygen content in their kilns, during multiple firings. These vases were useful for teaching about oxidation-reduction reactions since oxygen is a reactant, and a balanced equation can be written without using the half reaction method. This gave us an opportunity to review writing formulas for ionic compounds with different charges on the metals, a topic introduced earlier in the semester with 77
metal ores. The vases also reminded students that transition metal compounds are often colored, an observation based on the chemical formulas of paint pigments. Ancient glass objects in museum collections were used in lecture as examples for the objective “describe ways to modify glass: shaping methods, tempering, etching”. For homework students were asked to read the course manual, and use the course webpage to view websites on glass shaping techniques, then answer questions including “why was pottery developed before glass?” and “what are some methods to shape glass?” Another objective was “know what chemicals add color to glass”. Stained glass windows and the Lycurgus cup were used as examples of colored glass. Redox chemistry reappeared in the description of Egyptian strategies for decolorizing iron-contaminated glass. The chapter on building materials addressed the use of plaster for frescos, and the development of concrete by the Romans. The homework assignment asked “What benefits did concrete provide to Roman construction?” and “What is the difference in composition of Roman cement and Portland cement?” Figure 4 contains sample quiz and exam questions about the development of ceramics.
Figure 4. Assessment questions for ceramics. In summary, the course featured examples of historic and artistic interest for each class of material. Contrasts between examples from different periods of history demonstrated developments in natural resources and processing that improved the performance of materials in widely varying applications.
Art-Related Activities Personal interaction with materials in the lab allowed students to use all of their senses to observe the properties of specific examples. The surprise when materials didn’t behave as expected (nickel titanium “memory metal” was very different than copper wire) demonstrated the complexity of material properties. Several lab activities applied chemistry techniques to artistic samples. Analysis of Art Objects During an in-class activity students used theater gels to learn about UV-Visible spectroscopy. Manufacturers distribute sample packs containing small sheets of colored plastic, each backed with its transmission spectrum. Students had already seen that white light could be separated into different colors using a diffraction grating or prism, and were told that different colors had different wavelengths. The small group activity started with a comparison of absorption, reflection, and transmission of light by objects. Then the groups used a set of gels containing all of the colors of the 78
rainbow, along with a reference spectrum of visible light labeled with wavelengths, to determine how peaks and valleys in a transmission spectrum resulted in pure or mixed colors. Exam questions asked students to look at a transmission spectrum and identify the color of the transmitted light. Analytical chemistry techniques were introduced for an inquiry into the chemical composition of ceramic glazes. Before doing the lab students had learned that glazes have an aluminosilicate base, and that ground minerals could add color. The wish to preserve unique art objects necessitated nondestructive methods of testing. Students used Plumbtesmo and Cuprotesmo test strips from CTL Scientific Supply to check ceramic objects for the presence of lead and copper (15). The test strips are made of white paper with a coating that, when wet, will change color in the presence of a specific element. One type of strip was cut into rectangles, and the other into triangles, so that students could tell them apart. Each strip covered an area of about 0.5 cm2. A color change indicated that the appropriate metal was discovered.
Figure 5. Ceramics tested for metals: (a) dog; (b) tiger. Figure 5 shows two objects that were tested, a figurine of a dog and a salt shaker shaped like a tiger. Students could see that each object had been glazed with more than one color, and applied damp test strips to different areas on the sample. The tests for lead and copper were both positive for the dog, and both negative for the tiger. Following these tests, each sample was analyzed with an X-Ray Fluorescence spectrometer (XRF), which could detect a wide range of elements. Students had learned about the use of X-ray diffraction to determine crystal structures early in the semester; for this lab students were informed that the beam of X-rays was not intense enough to penetrate the object; it only reached layers of atoms near the surface. In our benchtop instrument an object was set on a plate above a hole, 1 cm in diameter, through which X-rays would reach the sample, then the cover was closed. A camera showed which part of the sample was exposed to the X-rays. Table 5. Elements Detected by Analytical Methods object
XRF (by decreasing abundance)
test strips
dog
Pb, Cu
S, Pb, Cu
tiger
none
Si, Ca, Pb, Zn, K, Ir, Fe, Zr, Mn, Cr, Th, Cu
Table 5 shows the elements found in the dog and the tiger. While the XRF detected lead and copper on the dog, confirming the test strip results, it also detected these elements on the tiger, contradicting the test strip results. A post-lab analysis question asked for an explanation for the different results. While most students proposed differences in accuracy or sensitivity of the techniques, some students figured out that both reports could be correct because different parts of the objects were tested by the different techniques. A test strip sampled one small spot on a surface, while the X-rays interacted with a wider area on the sample, and penetrated the glaze to a greater 79
depth. If the tiger had a clear glaze over the lead and copper containing layer, the test strip would not be able to detect those metals. Demonstrations of Intermolecular Forces with Artists’ Materials
Figure 6. Results of experiments with intermolecular forces: (a) various fibers dyed marigold or tea extracts and metal mordants; (b) food dyes separated on paper. As can be seen in Figure 6, dyes can be used to produce colorful materials and also observe the influence of intermolecular forces. Figure 6a shows fabric swatches, containing a variety of functional groups, dyed with boiling water containing tea (rows 1 and 2) or dried marigold flowers (rows 3, 4, 5); some dye baths also contained ionic compounds as mordants, which could influence the dye color as well as fastness (3). Rows 1 and 4 used iron, while row 3 used tin and aluminum. Paper chromatography was used to separate mixtures of dyes in McCormick food coloring (21). Prelab questions asked to determine the relative polarities of water and cellulose, based on their Lewis structures, and then predict whether the most polar dye would prefer the water or the paper. The chromatogram in Figure 6b shows that each bottle of food coloring contained two dyes. Students could use their results to determine that the blue dye was the most polar, and the pink dye was least polar. Syntheses of Artists’ Materials Several of the synthetic lab activities included an artistic component. Syntheses of a cross-linked polyester that could be used as paint binder (20), and of Prussian Blue, an artists’ pigment (22), introduced students to stirring hot plates, volumetric flasks, and vacuum filtration. As the structures of the chemicals changed, students observed dramatic changes in their physical properties. The polyester synthesis started with colorless phthalic anhydride, ethylene glycol, and glycerine. The color and viscosity changed as the solid melted, dissolved, then reacted with the other chemicals. As the reaction proceeded students needed to monitor the temperature and adjusted the hot plate; the polymerization was exothermic, so heat was not always needed, but additional activation energy was needed for the final crosslinking reaction. Figure 7a shows the final product, a beige cross-linked polyester in a beaker. As the reaction was carried out under a snorkle hood, filaments formed in the updraft and settled around the edges of the beaker. The complete process took about 90 minutes. In contrast to the slow condensation reaction, the synthesis of Prussian Blue was nearly instantaneous. Students prepared aqueous solutions of orange iron(III) chloride hexahydrate and yellow potassium ferrocyanide trihydrate in volumetric flasks. Mixing them in a beaker produced a dark blue precipitate which was collected by vacuum filtration. Students compared the properties of their synthetic pigment and two mineral pigments, red ochre and titanium white; mixed them with natural binders such as casein, egg yolk, and gum arabic (15); then tested their performance by 80
creating small paintings, as shown in Figure 7b. A similar lab experiment based on the synthesis of a zinc based pigment has been published recently (33).
Figure 7. Products of synthetic labs: (a) polyester resin and filaments; (b) painting with Prussian Blue; (c) colored silica glass. A sol-gel process was adapted for the synthesis of colored glass (23, 24). Students mixed tetraethylorthosilicate with ethanol, then added dyes or colored salts dissolved in aqueous solutions of hydrochloric acid or ammonia. Even with acid or base catalysis the reaction was not finished during one lab period. They transferred their reaction mixtures to cuvets, and observed their solid products the following week. Figure 7c shows samples made with marigold extracts, some with added iron or tin salts, and an acid catalyst. Food dyes were also used successfully. On one lab survey four students selected the preparation of colored glass as their favorite lab, and commented that they found it interesting that this process could be done at room temperature, but four other students selected it as their least favorite lab, and complained about the waiting time (90 minutes of stirring before pouring into molds). I added a side activity of etching glass slides with Armour Etch (15), and I will continue to look for additional activities to fill for the waiting time. Limits of the Laboratory Experience In the laboratory students performed detailed examinations of materials, which were recalled as examples to illustrate concepts in lectures and to answer questions on exams. For example, the identification of transition metal ions in colored glazes, and the different colors of iron compounds in the pigment synthesis, were connected to the effects of metal ions on the properties of glass, enamel, and bricks. Students also practiced scientific skills such as making and recording observations; using balances and glassware to make solutions; synthesizing and characterizing materials. However there was not enough time for a comprehensive exposure to the properties, processing, and performance of materials. The size of the class and rudimentary lab skills of the students also limited our ability
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to use advanced techniques and instrumentation. Processes requiring high temperatures, expensive reagents, or specialized equipment had to be studied in other ways.
Artists Show and Tell For processes that could not be performed in the laboratory, students watched videos demonstrating the preparation and/or analysis of materials. Although it is interesting to see how plastic bottles are mass produced in factories, it can be easier to observe the properties of materials when they are being manipulated by an artist. My students have watched videos of artists casting metal (34), blowing glass (35), and using a sustainable approach to throwing, glazing, and firing pots (36). In the videos artists showed us how they processed materials, and told us the properties they wanted to achieve in their creations. We were able to see properties changing during the processing. While watching videos students answered questions that asked them to compare and contrast the processing of hot metal (cooled fast to set structure) and hot glass (cooled slowly to avoid cracks), or of glass (cool to set structure, reversible) and clay (fire to set structure). I followed the videos with discussions of how the changes in chemical composition and atomic level structure that occurred during processing affected the macroscopic properties of the products. Little supplementary discussion was required after watching documentaries created for the NOVA television series. In addition to scenes of artists working with materials, these educational videos included interviews with science and engineering professors who explained the technical reasons for the success of these historic methods, as well as historians who described the cultural contexts for these objects. I distributed lists of questions about composition, processing, and performance of materials to answer while watching the videos. After the videos, students volunteered to share answers with the class, and I rarely needed to contribute any corrections. “Roman Bath” showed ancient designs being used to build a bath house from ceramic materials such as bricks and tiles (37). The project tested the performance of the materials when exposed to heat and water. Students recorded brief answers to the following factual questions: • • • •
What ceramic materials were used in construction of the bath? What modern materials were used in the construction? How is limestone converted to cement and mortar? What problems may be caused by accelerated drying times for the ceramics?
Students used prior knowledge of ceramics for a question about performance, • Why would ceramics perform better than in a bath than other types of materials? In “Samurai Sword” traditional methods were used to produce two types of steel from iron ore and charcoal, then combine them into a sword (38). Although we had previously discussed the chemistry of smelting, identified carbon as an interstitial impurity in steel, and considered the effects of work hardening and annealing on metal samples, the video dramatically synthesized key concepts in the context of a very specific application. The presenters clearly explained how the composition of the steel, and its processing, created a special structure, which in turn produced unique properties that resulted in outstanding performance. Students answered the following questions: • Describe the smelting process used to produce the steel (tamahagane) from which samurai swords are constructed. 82
• • • • • • • • •
What can go wrong during the smelting process? How does the incorporation of carbon affect the structure and properties of iron? What is the difference between hardness and toughness? How does carbon content affect the hardness and toughness of the steel? Why are impurities like sulfur and phosphorus problematic in steel? What happens to the steel as it is hammered? Why does the smith repeatedly heat the sword? Which type of steel (hard or tough) is used on the outside of the sword? Which type of steel (hard or tough) is used on the inside of the sword?
Examining the work of local artists was another opportunity for students to find chemistry in art. Students were encouraged to attend campus art exhibits, and prepare reports on the composition, properties, and processing of items on display, to earn credit in the campus events category. Students were asked to list the materials used in the exhibit, and classify them as metals, polymers, or ceramics; describe how they had been processed; and observe how they interact with light (a physical property).
Conclusions Examples from art and archeology illustrated important chemical principles in the course “Introduction to the Chemistry of Materials”. These objects were used to describe interrelationships among structure & composition, physical & chemical properties, processing, and performance; to analyze how the life cycles of materials affect an environment, society, and economy; and to demonstrate how the history of a civilization is tied to the development of materials, and to the sustainability of its practices. For this nonmajors class the skills and knowledge displayed on their final research papers is a useful assessment of their learning. For the assignment each student reported on a different advanced material, using a scientific news article from a source such as Chemical & Engineering News or The New York Times. The assessment of one set of papers showed that most could describe their material’s composition (97%), structure (80%), and the properties making its performance superior to older materials (83%). 70% could explain how their material’s synthesis & processing, or its performance, affected its sustainability. Studies have shown that students benefit from an enthusiastic instructor(39), and the incorporation of examples from art and archeology made teaching the course more fun. Learning the chemistry behind these beautiful and amazing objects has inspired me, and by discovering new examples every time I taught the course, my appreciation for the many possibilities of materials chemistry continued to grow.
Acknowledgments A UW Oshkosh Faculty Development Program summer grant funded the development of laboratory activities, and a sabbatical grant funded the creation of the course manual. The organizers and presenters of the NSF supported CWCS Chemistry in Art Workshop and cCWCS Advanced Chemistry in Art Workshop shared many interesting laboratory activities.
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Donahue, C. J. Reimagining the Materials Tetrahedron. J. Chem. Educ. 2019, 2682–2688. Mihalick, J. E.; Donnelly, K. M. Using Metals to Change the Colors of Natural Dyes. J. Chem. Educ. 2006, 83, 1550–1551. Orna, M. V.; Goodstein, M. P. Chemistry and Artists’ Colors, 2nd ed.; Chemical Heritage Foundation: Philadelphia, 1998. Ellis, A. B. Materials Science Track, Science at the Cutting Edge; Project Kaleidoscope Faculty for the 21st Century, 2001 National Assembly, Madison WI. Ellis, A. B. Teaching General Chemistry: A Materials Science Companion; American Chemical Society: Washington, DC, 1993. Ball, P. Designing the Molecular World: Chemistry at the Frontier; Princeton University Press: Princeton, 1994. Thrower, P. A. Materials in Today’s World, 2nd ed.; McGraw-Hill: New York, 1996. Ball, P. Made to Measure: New Materials for the 21st Century; Princeton University Press: Princeton, 1997. Amato, I. Stuff: The Materials the World Is Made Of; Basic Books: New York, 1997. Sass, S. The Substance of Civilization: Materials and Human History from the Stone Age to the Age of Silicon; Arcade: New York, 1998. Mihalick, J. E. Chemistry 104: Introduction to the Chemistry of Materials; http://www.uwosh. edu/faculty_staff/mihalick/materials/materials.html (accessed March 9, 2021). Mihalick, J. E. Introduction to the Chemistry of Materials; 2015 [unpublished course manual]. Hill, P.; Simon, D. Developing a Community of Science and Art Scholars. In Collaborative Endeavors in the Chemical Analysis of Art and Cultural Heritage Materials; Lang, P. L., Armitage, R. A., Eds.; ACS Symposium Series 1103; American Chemical Society: Washington, DC, 2012; pp 219-229. Hill, P. Handouts for Chemistry and Art Workshop; Center for Workshops in the Chemical Sciences 2009 [unpublished]. Geselbracht, M. J.; Ellis, A. B.; Penn, R. L.; Lisensky, G. C.; Stone, D. S. Mechanical Properties of Metals: Experiments with Steel, Copper, Tin, Zinc, and Soap Bubbles. J. Chem. Educ. 1994, 71, 254–261. Gisser, K. R. C.; Geselbracht, M. J.; Cappellari, A.; Hunsberger, L.; Ellis, A. B.; Perepezko, J.; Lisensky, G. C. Nickel-Titanium Memory Metal: A “Smart” Material Exhibiting a Solid-State Phase Change and Superelasticity. J. Chem. Educ. 1994, 71, 334–340. Flachskam, R. L., Jr.; Flachskam, N. W. Textile Fiber Identification: An Organic-Polymer Laboratory. J. Chem. Educ. 1991, 68, 1044–1045. Ingham, R.; Covey, E. The Costume Technician’s Handbook; Heineman Drama: Westport, CT, 1992 Most, C. F. Polyesters, Varnish, and Paint. Experimental Organic Chemistry; Wiley: New York, 1988; pp 487-492. Markow, P. G. The Ideal Solvent for Paper Chromatography of Food Dyes. J. Chem. Educ. 1988, 65, 899–900. Prussian Blue: Making the pigment. Pigments through the Ages. WebExhibits; http://www. webexhibits.org/pigments/indiv/recipe/prussblue.html (accessed March 9, 2021).
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23. Buckley, A. M.; Greenblatt, M. The Sol-Gel Preparation of Silica Gels. J. Chem. Educ. 1994, 71, 599–602. 24. Laughlin, J. B.; Sarquis, J. L.; Jones, V. M.; Cox, J. A. Using Sol-Gel Chemistry to Synthesize a Material with Properties Suited for Chemical Sensing. J. Chem. Educ. 2000, 77, 77–79. 25. Cooper, M. M. Cooperative Chemistry Laboratory Manual, 1st ed.; McGraw-Hill: Boston, 1996. 26. Humes, E. Garbology: Our Dirty Love Affair with Trash; Avery: New York, 2013. 27. Lambert, J. B. Traces of the Past: Unraveling the Secrets of Archaeology through Chemistry; Helix/ Perseus Books: Reading, MA, 1997. 28. Gannon, M. Hints of Colonial Pollution Hidden in Andean Ice Cap. Live Science; February 9, 2015; https://www.livescience.com/49740-potosi-silver-mines-ice-pollution.html (accessed March 9, 2021). 29. Leary, W. E. Mighty Moon Suits Are Falling Apart. The New York Times; December 5, 2000; https://www.nytimes.com/2000/12/05/science/mighty-moon-suits-are-falling-apart.html (accessed March 10, 2021). 30. The Turkey red process. National Museums Scotland; https://www.nms.ac.uk/collectionsresearch/our-research/highlights-of-previous-projects/colouring-the-nation/research/ dyeing-and-printing-techniques/the-turkey-red-process/ (accessed March 9, 2021). 31. Fackler, M. Old Ways Prove Hard to Shed, Even as Crisis Hits Kimono Trade. The New York Times; February 9, 2015; https://www.nytimes.com/2015/02/10/world/old-ways-provehard-to-shed-even-as-crisis-hits-kimono-trade.html (accessed March 9, 2021). 32. Neolithic Archaeology Photo Galleries. Expeditions at the Field Museum; https://expeditions. fieldmuseum.org/neolithic-archaeology/photo-galleries (accessed March 9, 2021). 33. Gaquere-Parker, A. C.; Hill, P. S.; Haaf, M. P.; Parker, C. D.; Doles, N. A.; Yi, A. K.; Kaminski, T. A. Pigment Synthesis for the Exploration of Binding Media Using a Lead-Free Alternative to Chrome Yellow. J. Chem. Educ. 2017, 94, 235–239. 34. Lim, G. UWO Metal Pour with Teresa Lind. UWOshkoshBeyond; YouTube, April 3, 2011; https://www.youtube.com/watch?v=42ay4kun62g (accessed March 9, 2021). 35. Chrysler Museum of Art. All About Glass Blowing (Introductory Class); YouTube, September 11, 2012; https://www.youtube.com/watch?v=XxgIEeIBCFo (accessed March 9, 2021). 36. Whitehead, J. Clay Wood Fire Spirit: The Pottery of Richard Bresnahan; Twin Cities Public Television, 1996. 37. Linde, N. Secrets of lost empires. II. Roman Bath. NOVA; WGBH Video, 2000. 38. Hamilton, D. Secrets of the Samurai Sword. NOVA; WGBH Video, 2008. 39. Moè, A.; Frenzel, A. C.; Au, L.; Taxer, J. L. Displayed enthusiasm attracts attention and improves recall. Brit. J. Educ. Psychol. 2021, e12399.
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Chapter 5
Using the History of Technology to Connect Art and Chemistry in a Science of Art Course for Nonscience Majors Brian McBurnett* Department of Chemistry, University of the Incarnate Word, 4301 Broadway, San Antonio, Texas 78209, United States *Email: [email protected].
Technological advances throughout history have not only led to advances in science but have also provided artists and designers new mediums of expression. In order to provide an approachable context to present chemical content to nonscience majors, a science of art curriculum was designed to present chemical content in correlation to art history highlighting technological advancements. The format of this course is designed to build in scientific complexity as it follows advancements in technology and art. With a concentration on visual art, the course starts with light and measurement and then introduces prehistoric cave paintings and their limited palette. Foundational chemistry is presented with the introduction of pigments found in ancient Egypt. Chemical reactions and stoichiometry are evaluated by precipitation of pigments, the formation of Greek pottery, and the chemistry of frescoes. As technology advances, oil painting is developed in the early Renaissance and provides context for the introduction of chemical bonding and organic chemistry. Technological breakthroughs over the past 200 years provide an entirely new method of expression with the discovery of synthetic dyes, photography, acrylic paints, and polymers. These advances allow for better scientific understanding and an expansion of artists palettes. Students are evaluated using a pretest and posttest Chemical Concepts Inventory and also express that connection between science and art enable them to better utilize existing and future technologies in their fields.
Using art to connect students to science at the undergraduate level has been well documented (1, 2). In particular, art engages students that are initially resistant to learning chemistry and provides nonscience majors an excellent method of learning chemical content in an approachable context (3). In Bright Earth: Art and the Invention of Color, Philip Ball well demonstrates how art has evolved throughout history and often in direct correlation with scientific and technological advancements (4). This has increasingly led to the development of the field of “technical art history” where scientific © 2021 American Chemical Society
analysis of artist materials and their techniques are evaluated in addition to the aesthetic contribution of the art (5). Technological advances have provided for a greater understanding of science and art and have developed an ever-expanding palette for both expression and analysis. In that regard, attending a Chemical Collaborations, Workshops, and Community of Scholars (cCWCS) workshop provided inspiration and excellent assistance in creating this course (6). Chemical concepts are presented in correlation with advancements in both art and technology. The primary goals this course are as follows: • To provide nonscience students a foundation in fundamental chemistry and an appreciation for science in its connection to the development of art. • To emphasize technological advancements that have historically provided fundamental advancements in both art and science. • To demonstrate that continual technological progress will contribute to the future advancements of both science and art. Initially this course was conceived to span both science and art with an array of topics including ceramics, glass, and metalwork. After three years of experience, this course has evolved to concentrate more on the interface of chemistry and art with significant focus on painting (7). The evolution of painting media is predicated on technological advancements that coincide with an ever evolving understanding of chemistry. Early painting had transformed from using ancient ochres to the predominant use of watercolors, encaustics, and tempera. With the discoveries of new elements, new pigments were developed and breakthroughs in the synthesis and isolation of compounds have provided for vibrant oil paints and the entire class of acrylic media. This same thousand-year transformation is mirrored in the advances in photography from early daguerreotypes to film to digital photography over the past 200 years (8). The format of this course is designed to build in scientific complexity as it follows advancements in art and examples used in class introduce these chemical concepts based on materials used in the creation of paintings. With this foundation of chemistry, it is the objective of this course that students will find an appreciation and understanding of science as well as the tools to evaluate future advances in both fields.
Course Structure and Content This course has been taught over the past 3 years each Fall semester with an average of 20 students majoring in art, computer graphic arts, fashion, and graphic design. The class meets for a 75-minute lecture twice a week for 15 weeks. In addition to the lecture course there is a separate and associated 3-hour laboratory course. The basis of this class is to provide a science credit for nonscience majors and directed to forming a connection of art and science thorough the advancements in technology. The scientific rigor of this course was loosely based on a general, organic, biochemistry (GOB) type class. The textbook used for the lecture course is Chemistry: Homework Helpers by Greg Curran and is an inexpensive guidebook for chemical content (9). The timeline of this course is divided into three sections increasing in complexity and depth of material. The initial section involves a 3–4 week introduction to light, measurement, and color. From this foundation, the second section involves a foundation of chemistry including atoms, compounds, and mixtures, precipitation, acid/base, and redox reactions and stoichiometry. The second segment of the course is presented over a 5–6 week period and roughly corresponds to a chronology of ancient (15000 BC) to medieval art (1400). Molecular shape and polarity, intermolecular forces, 88
introductory organic chemistry, and natural and synthetic polymers, correspond to the third section and the final 5–6 weeks of the course and align with art ranging from the Renaissance to modern (1400 to present day). Homework assignments are given throughout the semester, an exam is given after each of the three sections, and a comprehensive final at the end of the semester to measure comprehension of course content. A “Chronology of Scientific Discoveries and Artifacts” from Appendix 1 of R. Buckminster Fuller’s Critical Path is presented at the beginning of the semester to introduce students to the historical record of scientific and technological advancements (10). A summary of course content is found in Table 1. Table 1. Course Content, Connections to Art, and Selected Technological Advancements Course content
Connections to art
Technological advancements
Section 1 topics
Color and vision
Light Measurement Dimensional analysis Subatomic particles Color
Additive and subtractive color Vision
Electromagnetic radiation Light and vision Democritus’s theory of atoms
Section 2 topics
Ancient to medieval art (15000 BC – 1400)
Chemical reactions
Atoms, compounds, and mixtures Chemical reactions (precipitation, acid/base, and redox) Stoichiometry
Cave paintings Synthesis of pigments Encaustic Watercolor Greek pottery Frescoes
Synthesis of Egyptian blue Discovery of new elements Lenses Copper etching Leonardo da Vinci
Section 3 topics
Renaissance to modern (1400 – present)
Advances in synthesis and techniques
Bonding and structure Introductory organic chemistry Intermolecular forces Polymers Photochemistry
Oil paints Painting supports Synthetic dyes Acrylic paints Photography
Dalton’s atomic theory Periodic table Perkin aniline dye Kekulé organic chemistry Photography
Section 1: Light, Measurement, and Color The semester is started with the introduction of the phenomena of light and the electromagnetic spectrum. Scientists continue to test their ideas and make hypotheses regarding the nature of light. An excellent resource for the introduction of this topic is the book Seeing the Light for analysis and discovery of this material at a level appropriate to nonscience majors (11). Chapters 1 (Fundamental Properties of Light), 9 (Color), and 10 (Color Perception Mechanisms) are particularly helpful instructor resources. Students are introduced to measurement and dimensional analysis involving the relationship between color, wavelength, and frequency and are given homework problems, guided “mini-lab” activities in the laboratory, and tested at the end of the section with an exam (12). Properties of light are discussed including both additive and subtractive color formation, the BeerLambert law, and electron transitions that correspond to the perception of color (13). In addition, 89
the laboratory course includes hands-on activities of mixing both lights and pigments to demonstrate differences in additive and subtractive primaries. There is also a brief introduction into the chemistry of vision and the receptors in the eye in order to foreshadow material that will be presented later in the semester. Section 2: Atoms, Reactions, and Stoichiometry After the introduction to science in the first part of the semester, students then are introduced to atoms, compounds, and mixtures found in the cave paintings of prehistory (14). The pigments used in these ancient paintings: black, white, red, yellow, and brown, all provide an introduction to elements (the charcoal of carbon black), compounds (calcium carbonate – white, red and yellow of the iron ochres FeO(OH) and Fe2O3 and manganese oxide – black), and mixtures (earth – brown). In addition, the technological advances of using carbon for isotopic dating and the role of transition metals for many pigments throughout history are presented in the lecture as chemical analysis for a more in depth understanding of art. The focus of this section is on fundamental chemistry and is correlated with ancient to medieval art. The book A Chronology of Art edited by Iain Zaczek provides a clear timeline and approachable guide for a progression of art topics throughout history (15). In addition, The Brilliant History of Color in Art by Victoria Finlay is an excellent instructor resource for individual compounds and their history (16). Many of the compounds used in modern pigments have only relatively recently been discovered and students are guided though a historical timeline of pigment usage from the Pigments through the ages web site (17). Inorganic nomenclature is also introduced using historical pigments and their common names, for example vermillion, mercury(II) sulfide (HgS) and King’s yellow, diarsenic trisulfide (As2S3). Balancing equations and stoichiometry are introduced using the chemical reactions for the formation of pigments and for the formation of frescoes (18). The role of synthetic chemistry in art is presented in reference to the formation of Egyptian blue, considered to be the earliest synthetic pigment (19). As it is found in ancient Egyptian encaustics, this pigment is presented in the lecture and also synthesized in the laboratory section of the course. It is an excellent introduction to the complexities and beauty of chemistry.
Precipitation reactions are presented in production of historical pigments, acid/base reactions are shown in the chemistry of copper etchings, and redox reactions are shown in the evaluation of the production of ancient Greek pottery. When possible, reactions are placed in context with the usage and timeframe. For example, the pigment lead white, Pb2CO3(OH)2, has been in use for hundreds of years. The reaction of this pigment with hydrogen sulfide from gas lamps turns this pigment from white to a black lead(II) sulfide, PbS.
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Subsequent, conservation of artwork with lead white pigment involves gently applying hydrogen peroxide to restore the color.
In this example, it is interesting to show students that the resulting white lead(II) sulfate is chemically different and not the original pigment put down by the artist. In addition, as the toxicity of lead has become apparent in more recent times, the use of this pigment has greatly diminished. Section 3: Bonding, Intermolecular Forces, and Polymers Art history courses are often divided into ancient to medieval and medieval to modern sections, and this is the division is also reflected in the chemistry content presented. From the foundational chemistry learned in the previous section, this section concentrates on presenting Lewis structures and VSEPR theory, polarity and intermolecular forces, introductory organic chemistry, and polymer chemistry. Technological advancements provide fundamental breakthroughs in this era to provide not only an increased understanding of chemistry but also an expansion of the artist’s palette. The complexity of paint chemistry evolves rapidly during this time period from the use of inorganic pigments in an oil binder to purely synthetic organic pigments in a synthetic organic binder. A similar evolution unfolds in the advancements in photography from early daguerreotypes, to film, to modern digital photography. Lewis structures and VSEPR theory are presented in this part of the course and the concepts are well received by art and design students. Lewis structures, the shape and polarity of water, ammonia, methane, and other simple organic molecules allow for a discussion of their role in the formation of paints. Technological advances in glass making allow for glass lenses and the distillation and refining of oils gave rise to masterful oil paintings particularly well displayed in the art of Jan van Eyck (22). The three-dimensionality of chemistry corresponds well with the development of perspective and dimensionality in Renaissance art. Introductory organic chemistry is also introduced in this third section and provides students with additional insight in the chemistry of color. Simple organic molecules are present and displayed along with the structure of oils and the natural dyes of alizarin, purpurin, cochineal, indigo, and Tyrian purple. Indigo has been used since antiquity and is a natural dye found in plants whereas Tyrian purple is the dye of royalty requiring the harvesting of thousands of marine shellfish to produce any significant amount of dye (23). Students find it particularly interesting that the subtle addition of two bromine atoms to the ubiquitous indigo molecule leads to a significant change in dye color to give Tyrian purple.
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This chemistry is an excellent segue to the revolutionary advancement for both science and art in William Perkin’s synthesis of mauvine (24). The start of the 1800s could be considered the start of chemistry with the development of aniline dyes. An entirely new industry of dye making was created giving an entirely new palette of colors for artists and designers. Students are also presented with the structure of natural polymers such as cellulose and silk and how dyes and paint interact with these surfaces. With the widespread transformation of our chemical knowledge the evolution of synthetic chemistry an entire new class of acrylic paints and synthetic pigments provide are available to the artist. Our technological advancements have rapidly increased the timescale for advancement in both science and the arts. The evolution in painting is also reflected in the evolution and development of photography over the past 200 years on a much faster time scale. Students at the end of the semester are asked to reflect on how future technological advancements such as advanced materials, LEDs, computer technology, and 3-D printing will also affect this evolution of both science and art in the years to come.
Chemical Concepts Inventory Evaluation of student learning is a challenging endeavor and in particular, for a nonscience majors course, course learning objectives and outcomes are not as specifically defined as compared to a traditional chemistry course sequence (25). In order to evaluate the effectiveness of the material presented in this science of art course, for the past 3 years, a pre/posttest Chemical Concepts Inventory was used on the first day of class and the last day of lecture before the final. The Chemical Concepts Inventory is a 22-question multiple choice exam which is designed to assess and evaluate both content knowledge and reasoning of chemical concepts of high school and first year college students (26). The past three year results for pre/posttest class percentages for Fall 2017 (34.5% pretest/39.8% posttest), Fall 2018 (31.8% pretest/41.6% posttest), and Fall 2019 (34.2% pretest/ 42.3% posttest). Calculated the normalized learning gains from 2017, 2018, and 2019 are 5.3%, 9.8%, and 8.1%, respectively which is similar to literature reports of an average of 7% (27). Most but not all students scored higher on their posttest evaluation and the learning gains are encouraging. In addition, it is refreshing to see that student comments coincide with the intent of the course: “Chemistry and art will always be intertwined.” “Throughout this semester I’ve learned a lot about the art aspects in science and the science aspects in the art. An interesting realization or discovery that I’ve come across is how throughout time, people have found ways to advance the way science and art are used in technology.”
Discussion and Conclusions Supportive student feedback and positive learning gains are encouraging outcomes in teaching this course. The interdisciplinary nature of this course does provide a wealth of source material but is difficult to discern what to highlight, what to emphasize, and what to discard. In addition, due to the lack of prerequisite coursework for students enrolled in this course it is challenging to gauge the appropriate level of difficulty in the science presented. Art is a vast field, and the depth of material can range from K-12 science to graduate level analytical chemistry. The evolution of this course to a concentration in painting has been a part of determining of both what is most enjoyable for the students and what is most effective in presenting the chemical content. Although this course is based on a general, organic, biochemistry (GOB) type class, the material could be adapted for a 92
general chemistry class and additional modules could be enhanced to provide a full year of general chemistry. In its current iteration, the format of this course is ambitious. In its title, a “Science of Art” class is by definition vast and grand and it is a challenging task to give full justice to either subject. The connections between these two fields do provide and excellent context in which to engage nonscience majors into the science and the subsequent chemistry behind art. Advancements in technology continually improve our understanding of science and expand our artistic palette. Technological breakthroughs provide an entire new method of expression with each advancement and even something as innocuous as the creation of metal tubes to hold paint suddenly changed the artists the ability to go outside and paint in plein-air. A foundation of chemistry will give students the ability to fully appreciate the science behind the art. However, one significant challenge of this course is the diversity of source material. Due to the grand scope of the course, a wide variety of reading material is required and there is no single source covering all of the topics presented. The resources that are most often refenced for inclusion in lecture are included in table 2. Table 2. Suggested Instructor Resources Ball, P. Bright Earth: Art and the Invention of Color, 1st American ed.; Farrar, Straus and Giroux: New York, 2002. Falk, D. S.; Brill, D. R.; Stork, D. G. Seeing the Light: Optics in Nature, Photography, Color, Vision, and Holography Including a New Chapter on Digital Photography; 2019. Zaczek, I. A Chronology of Art; Thames & Hudson: New York, NY, 2018. Finlay, V. The Brilliant History of Color in Art; The J. Paul Getty Museum: Los Angeles, 2014.
Developing a workbook or textbook for this course would be the next goal of this project. In addition, a more detailed timeline would be a benefit as many of the technological advances in one era are often lost and rediscovered in another. The objective of this course is to connect science and art through the common thread of technological advancement. This will allow students to critically evaluate emerging new technologies and their choice in materials. Due to the increasing pace of new discoveries, these connections should serve these students in the appreciation and preservation of their current work and in their implementation of their future projects.
Acknowledgments The author would like to thank the Department of Chemistry, the Department of Fine Arts, and the School of Media Design at the University of the Incarnate Word for support of this project. In addition, with their enthusiasm and interest, the students in these classes are greatly acknowledged.
References 1. 2.
Kafetzopoulos, C.; Spyrellis, N.; Lymperopoulou-Karaliota, A. The Chemistry of Art and the Art of Chemistry. J. Chem. Educ. 2006, 83 (10), 1484–1488. Nivens, D. A.; Padgett, C. W.; Chase, J. M.; Verges, K. J.; Jamieson, D. S. Art, Meet Chemistry; Chemistry, Meet Art: Case Studies, Current Literature, and Instrumental Methods Combined To Create a Hands-On Experience for Nonmajors and Instrumental Analysis Students. J. Chem. Educ. 2010, 87 (10), 1089–1093.
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4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.
21.
22.
Hemraj-Benny, T.; Beckford, I. Cooperative and Inquiry-Based Learning Utilizing Art-Related Topics: Teaching Chemistry to Community College Nonscience Majors. J. Chem. Educ. 2014, 91 (10), 1618–1622. Ball, P. Bright Earth: Art and the Invention of Color, 1st American ed.; Farrar, Straus and Giroux: New York, 2002. Wells, G.; Haaf, M. Investigating Art Objects through Collaborative Student Research Projects in an Undergraduate Chemistry and Art Course. J. Chem. Educ. 2013, 90 (12), 1616–1621. Hill, P. S.; Simon, D.; Hartman, M.; Uffelman, E. S. NSF Chemistry Collaborations, Workshops and Community of Scholars (CCWCS) Workshop: Art as Context for General Chemistry; 2017. Friedstein, H. G. A Short History of the Chemistry of Painting. J. Chem. Educ. 1981, 58 (4), 291. Sattar, S. The Chemistry of Photography: Still a Terrific Laboratory Course for Nonscience Majors. J. Chem. Educ. 2017, 94 (2), 183–189. Curran, G. Chemistry; Homework Helpers; Career Press: Pompton Plains, NJ, 2011. Fuller, R. B. Critical Path; St. Martin’s Press: New York, N.Y, 1981. Falk, D. S.; Brill, D. R.; Stork, D. G. Seeing the Light: Optics in Nature, Photography, Color, Vision, and Holography Including a New Chapter on Digital Photography; 2019. Bopegedera, A. M. R. P. The Art and Science of Light. An Interdisciplinary Teaching and Learning Experience. J. Chem. Educ. 2005, 82 (1), 55. Orna, M. V. Chemistry and Artists’ Colors. Part I. Light and Color. J. Chem. Educ. 1980, 57 (4), 256. Finlay, V. Color: A Natural History of the Palette; Random House Trade Paperbacks: New York, 2004. Zaczek, I. A Chronology of Art; Thames & Hudson: New York, NY, 2018. Finlay, V. The Brilliant History of Color in Art; The J. Paul Getty Museum: Los Angeles, 2014. Douma, M. Pigments Through the Ages; http://www.webexhibits.org/pigments/intro/history. html (accessed Mar 1, 2021) De Brabandere, S. The Science of Frescos; https://www.scientificamerican.com/Article/theScience-of-Frescos/ (accessed Mar 1, 2021) Giménez, J. Finding Hidden Chemistry in Ancient Egyptian Artifacts: Pigment Degradation Taught in a Chemical Engineering Course. J. Chem. Educ. 2015, 92 (3), 456–462. Vyhnal, C. R.; Mahoney, E. H. R.; Lin, Y.; Radpour, R.; Wadsworth, H. Pigment Synthesis and Analysis of Color in Art: An Example of Applied Science for High School and College Chemistry Students. J. Chem. Educ. 2020, 97 (5), 1272–1282. Conservation Unit of the Museums & Galleries Commission in conjunction with Routledge. An Introduction to Materials; Science for Conservators; Routledge: London and New York, 1992. Vision & Material: Interaction between Art and Science in Jan van Eyck’s Time; [Papers Delivered at the International Conference in Brussels in the Royal Flemish Academy of Belgium 24 - 26 November 2010 at the Occasion of VLAC’s Double Lustrum]; De Mey, M., Martens, M. P. J., Stroo, C., Koninklijke Vlaamse Academie van België voor Wetenschappen en Kunsten, Eds.; KVAB Series Academica; KVAB Press: Brussels, 2012.
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23. Cooksey, C. Tyrian Purple: 6,6′-Dibromoindigo and Related Compounds. Molecules 2001, 6 (9), 736–769. 24. Garfield, S. Mauve: How One Man Invented a Color That Changed the World, 1st American ed.; W.W. Norton & Co: New York, 2001. 25. Holme, T. A.; Luxford, C. J.; Brandriet, A. Defining Conceptual Understanding in General Chemistry. J. Chem. Educ. 2015, 92 (9), 1477–1483. 26. Mulford, D. R.; Robinson, W. R. An Inventory for Alternate Conceptions among FirstSemester General Chemistry Students. J. Chem. Educ. 2002, 79 (6), 739. 27. Pentecost, T. C.; Barbera, J. Measuring Learning Gains in Chemical Education: A Comparison of Two Methods. J. Chem. Educ. 2013, 90 (7), 839–845.
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Chapter 6
Making Light Work: A First-Year Writing Course on Art, Colors, and Chemistry Benjamin J. McFarland* Department of Chemistry and Biochemistry, Seattle Pacific University, Seattle, Washington 98119, United States *Email: [email protected].
Recently Seattle Pacific University adopted a general education curriculum built around the student writing experience, in which students are required to learn to write within the context of a specific discipline in their first year. A first-year course in chemistry writing poses a pedagogical challenge, because understanding professional scientific writing requires multiple years of study. This challenge was addressed in the class described here by focusing on the chemical analysis of color in art. Historical examples ranged from reconstructing the synthesis of Egyptian blue pigment to detecting a lost Van Gogh painting that the artist had painted over. Student learning outcomes included reading and writing about the history of colors in art and pigment analysis, making their own pigments in the lab, then using those pigments to create paintings. Students progressed through four experiences at the interdisciplinary interface of art, archaeology, and chemistry: 1.) They learned how pigments were made in different historical eras, and how artworks and artifacts are analyzed with chemical techniques; 2.) They analyzed the color palette of an artwork of their choice in CIELAB space (using the online GENI-ACT platform to facilitate authentic research in the classroom); 3.) They synthesized, separated, and tested red, yellow, green, and/or blue pigments in five laboratory sessions; and 4.) They used those pigments to create their own artwork at the end of the course. This final paper and the student-created artwork constituted substantial, tangible outcomes that demonstrated the students’ ability to read about, contextualize, analyze, and even create art.
© 2021 American Chemical Society
Introduction In 2016, Seattle Pacific University (SPU) reconfigured its general education curriculum to focus on writing. We designed a two-course sequence in which the first course, WRI 1000 Academic Inquiry and Writing, teaches students rhetorical strategies and analysis, while the second course, WRI 1100 Disciplinary Research and Writing Seminar, assigns students a literature research project that culminates in a substantial final paper. As a member of Faculty Governance at SPU, I helped design this curriculum and so I chose to implement it in the classroom as well. Each faculty member teaches this course from the standpoint of their particular discipline. For example, an English professor teaches students to read and write about the latest edition of a literary journal. The goal of this particular section is to teach students to do the same with chemistry journals. Teaching a disciplinary research and writing seminar to students in their first year in college has specific challenges when the context is the discipline of chemistry. Students are not required to be chemistry majors to take this course, and are typically in their second quarter of university instruction. No scientific prerequisite courses are associated with WRI 1100, so that the student population choosing to enroll in the course is broad. Scientific instruction must be appropriate to non-majors, yet the disciplinary literature in chemistry is highly specialized and technical, written to an audience with a knowledge base assuming years of education in the topic. Inexperienced students must be introduced to a literature that requires a certain amount of experience, and must learn to write in a technical, objective style. Yet the advantages of student interest in the universal experience of perceiving and making colors give impetus to overcome these challenges. WRI 1100 therefore explores three simultaneous topics: 1. Chemistry: The history of mining, purification, and synthesis of colors, and current analysis of colors in artworks. 2. Art: The use of pigments in art and archaeological artifacts, including how new pigments influenced artistic practice. 3. Writing: Finding, reading, summarizing, and synthesizing peer-reviewed journal articles on these topics from chemistry and art into a final paper comparing the use of two chemical techniques for analysis of pigments in paintings or artifacts. The confluence of these three topics is demonstrated for the class in the practice of art conservation and restoration, and in the use of chemical analysis in art museums. The National Gallery of the United Kingdom in London, like many prominent art museums, publishes its own journal, the Technical Bulletin of the National Gallery, which publishes scientific studies of artworks (1). The Louvre Museum in Paris houses a particle accelerator, the Accélérateur Grand Louvre d’Analyse Elémentaire (AGLAE), used for sensitive on-site analysis of artworks and artifacts. The studies carried out at these institutions involve chemical techniques, reasoning, and concepts that the students can learn by reading the technical literature as they also learn to write in that style. Chemistry education journals include many examples of how the gap between non-majors and technical writing has been addressed by putting chemical topics into the context of art and archaology in the classroom, which are cited in the context of the class below. Many of these articles include protocols for synthesizing pigments in the undergraduate laboratory. The gap can also be addressed through hands-on laboratory experience. In the second half of the class, weekly 80-minute laboratory sessions are scheduled during class time during which the students make pigments, mix them with different binders, and test how paints make colors on canvas. In the final laboratory session, students bring together a palette of colors from their synthesized pigments and paint the canvas according 98
to their own artistic ideas. Keeping a laboratory notebook and interpreting what happened in the laboratory require use of words and writing, and reinforce the goals of the class to teach the students to write and think scientifically. The general education requirements of SPU restrict this class to a small size (20 students) that is similar to a typical lab section and can be accommodated in a teaching lab. Laboratory classes were scheduled during the typical course time block on Mondays during the second half of class. This course was first offered in Winter 2020, and then in Winter 2021 it was repeated under the hybrid learning model required by our institutional COVID-19 protocols, in which in-person classes were socially distanced. In Winter 2021, the class size was restricted to 16 students to allow proper distancing. About one-quarter of the students are chemistry majors, and one-half are science majors such as biology or related majors such as nursing, which require chemistry courses. The remaining one-quarter of students are not required to take chemistry for their majors, although some are art or psychology majors and approach this subject from the starting point of the liberal arts.
Lecture: Twelve Questions and a Writing Project A focused sequence of lectures with participatory elements was developed to teach first-year students to read an academic study of the chemical analysis of color in art, then to write summaries and syntheses in the same style. These were framed with twelve questions about color, chemistry, and art. Class sessions designed around these were interspersed with sessions about using the library, conducting literature research, and then practice drafting and peer-reviewing sections of the final report. The final report consists of choosing two techniques, invasive and non-invasive, to compare and contrast in terms of the way they work, the evidence they provide, and the colors they have found or recovered. Students find three or four peer-reviwed articles describing the use of each technique on different artworks, for a total of six to eight articles, and synthesize the findings into recommendations for the use of each technique and examples of syngery between techniques. Although this task may seem daunting to first-year students at first, with scaffolded instruction in focused topics, they can read and write about these articles and accomplish the disciplinary research and writing goals of the class. A. “What is a Flame?” Michael Faraday’s classic 1848 lecture The Chemical History of a Candle serves as the starting point for the class. In this lecture, Faraday described the chemical reactions in a candle and how they relate to its color through demonstration. As students recapitulate some of his reasoning, they think of the candle as a complex, dynamic system. In addition, candles produce soot comprised of incompletely combusted carbon particles, which is a reaction used to produce charcoal, one of the first pigments used by humans. This means that the students learn about light, color, and pigment chemistry at an introductory level. We followed Faraday’s example and performed simple experiments on tealight candles in class. Also, a large taper was used for demonstrations. Students observed their candles closely and answered guided questions as others have described (2, 3). Students learn that black-body radiation connects color and temperature for solid materials including soot particles in a candle. Students write a paragraph answering “How does a candle burn?” as the initial homework.
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B. “How Does Science Work?” Students are introduced to the process of science and the language used in the methods section of a scientific paper using episodes of the TV show Mythbusters, as described in an activity used within a psychology class (4).Students analyze the experiment represented in the show they chose and consider the differences in audiences and style between the media of television and academic, written scientific publishing. Students discuss which episode they chose to watch and write a paragraph-long methods section for an experiment conducted in that episode, using objective, precise terms and passive voice. Although a mixture of active and passive voice is preferable for advanced writers, a simple rule regarding passive voice is given, following a lexical analysis that found most authors use passive voice frequently in the methods sections of ACS journals (5). The paragraph they write is edited to show how to make it more objective and replicatable. C. “How Did Science Find a Hidden Van Gogh Portrait?” The first peer-reviewed scientific journal article students read was published in Analytical Chemistry and concerned used of synchrotron radiation to detect elements in a portrait that Vincent Van Gogh had overpainted with another painting (6). The primary technique used in this investigation was X-ray fluorescence (XRF) in elemental mapping, but the authors refer to previous methods such as X-ray radiation transmission (XRR) and infrared reflectography (IRR), and provide additional evidence from X-ray absorption near edge structure (XANES). These four techniques are commonly used to analyze art, so this paper teaches students to interpret the data from each, which includes interpreting similarity among spectra with complex shapes for the identification of the pigment Naples Yellow. Students also read articles that summarize and restate the research for different audiences: a press release (7) and an excerpt of a review article that discusses the research (8). Students write a paragraph-long annotation of this article for an annotated bibliography, which is the first step in their writing project. The authors of this study have published additional accounts of other overpainted artwork, one of which is suggested to students as a starting point for their own research into the field (9). The paragraph written by the students is edited for scientific style and appropriate level of detail. D. “How Does Color Work?” The physical relationship of color to wavelength and energy is the next topic, including how molecules fluoresce when they absorb and then emit light of a longer wavelength. In-class demonstrations for this include how light “works” by moving a radiometer (10) and UV fluorescence in household objects (11). Because students readily conceive of both wavelength and energy as a quantity, and because students can collect reflectance spectra with an application using their phone camera (e.g., the app Albedo by Thomas Leeuw) (12) the objective, quantitative depiction of color as reflectance spectra is a logical next conceptual step. Students ask a question comparing colors among images or within images and address that question by collecting red, green, and blue reflectance values and then estimating the shape of the reflectance spectrum. This reinforces interpretation of spectra as shapes that can be compared and sorted. The students are assigned to formulate a hypothesis comparing colors, investigate it with their camera, and write a paragraph interpreting the results as homework after the class. This helps them learn to organize data and write about an experiment in technical language as preparation for the later writing assignments.
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E. “How Were Natural Colors Found?” Students are asked how they would make colors if they had to use the colors found by walking around outside. They compare their ideas to the colors obtained locally as used by the New Mexican Santero Jose Armijo, which include red and green clays, black chimney soot, and yellow ochre (13). The same process of filtering the natural world for chemically accessible color led to rock art and cave paintings. Today these artworks are best analyzed with portable XRF, which was used, for example, to document rock paintings in the Lower Pecos Canyonlands and to discover pigments hidden under solid layers, a situation like the hidden Van Gogh painting (14). A study showing that black pigments do not contain manganese but rather carbon shows the uses and limitations of the portable technique, and demonstrates how to read a different kind of spectrum (15). A discussion of natural red dyes introduces the importance of structure and organic chemistry, and contains absorbance spectra of the soluble dyes for comparison to the reflectance spectra in their context. The different colors of anthocyanin hair dyes extracted from blackcurrant waste at different pH values shows how even small changes in structure can change the color of a solution (16). For the historical lectures, students are required to keep a “Color Notebook” of notes from each lecture, which are collected as scanned documents along with other short writing assignments. These allow the students to practice low-stakes reflective writing on topics that will broaden their knowledge base for reading the literature and writing the final project. F. “How Were the First Synthetic Colors Made?” The first synthetic color, Egyptian blue, and its convergent cousin pigment, Han Blue, are the first pigments in a historical review of the synthesis of artificial blue pigments. Egyptian blue’s luminescence in the near-infrared recalls the lesson on energy and fluorescence, and shows potential utility as a fingerprint dusting powder (17). The chemical source of the color of natural ultramarine in the Medieval Era, which was reproduced artificially in the 19th century, shows a second way to arrange inorganic atoms to make the color blue, as a caged trisulfide anion (18). The examples of blue smalt and Mary Virginia Orna’s experience recreating a medieval blue pigment recipe (19) show how medieval and modern pigment synthesis recipes use language differently. Other blue pigments are compared to early synthetic blue pigments using reflectance, converting RGB coordinates to CIE L*a*b* color space (20). This expands on the previous example of comparing reflectance spectra and shows how the two-dimensional CIE L*a*b* color coordinates are more intuitive than threedimensional RGB or other coordinates, resulting in their use in the fashion industry. The graphical conversion helps the students learn to read different kinds of graphs representing color quantitatively, which prepares them to read similar graphs in their literature research. G. “How Were New Colors Made in Medieval Times?” The Medieval Era contained a mix of restriction and innovation in the chemistry of colors. In Europe, recipes for synthetic pigments such as Egyptian blue and yellow lead alloys (21) were lost and color palettes focused on three expensive colors: red vermilion, yellow gold, and blue ultramarine. Simultaneously, the Islamic Golden Age was laying the groundwork for the transformation of alchemy to chemistry, an intellectual process that also influenced the Late Middle Ages in Europe. Several chemical innovations were made in this context, some inadvertently. Some of the colorful stained glass windows of Chartres and other cathedrals result from gold and silver nanoparticles formed when the precious metals were added during glassmaking (22). Such nanoparticles are 101
surprisingly easy to make and colorful, with many modern uses (23). The lecture includes several examples of current nanotechnology to show how novel, colorful chemistry can lead to multiple applications. Historically, science also led to a new way to make colors on wood and canvas, as Albert Magnus’s innovative process of distillation allowed separation of oils, the essential step for the Dutch to develop oil painting in the 15th century at the end of the Medieval Era (24). These historical topics introduce chemical concepts such as absorbance vs. reflectance, and refractive index, including a description of how light moves through fiber-optics as used for analysis of paintings in fiber-optic reflectance spectroscopy. H. “How Did Scientists Synthesize New Colors?” The synthesis of new colors with science depended on serendipity in the same way that the discovery of stained glass nanoparticle-derived colors did. Prussian blue (the first new synthetic color since the ancient synthetic blues), mauvine, and synthetic indigo contained different proportions of planning and luck, but also had social and economic implications. For example, synthetic indigo shifted economic development away from colonial plantations and toward companies that carried out organic synthesis, reshaping the flow of money, ideas, and people throughout the world (25). These broader implications are important to include in a liberal arts context for non-majors to connect chemistry to history and social science. The new inorganic and organic pigments are summarized in tables for the students to review the general differences in structures and properties between the two categories (26). The success of synthetic chemistry in making new colors inspired the chemist Marcelin Berthelot to give an 1894 speech titled “Chemistry in the Year 2000” that predicted that chemical advances would allow food to be synthesized rather than grown, displacing agriculture (27). The students can discuss why this prediction has not been fulfilled in person or in a argumentative writing assignment. I. “Why Do Colors Fade and Make People Sick?” The fact that the Second Law of Thermodynamics applies to colorful molecules the same as to everything else has important implications: all colors are subject to degradation, and the body has not evolved defenses against toxicity. Students learn the chemistry of how these processes occur. The discovery of new elements like chromium led to chrome yellow pigment, which Van Gogh used to paint sunflowers. Over time, photoinduced reduction turns these painted flowers brown through a mechanism investigated with synchrotron XRF, Raman, and FT-IR (28). Another familiar Van Gogh painting, Bedroom in Arles (1888), is familiar in a degraded state: red lead pigment in the walls faded to white lead carbonate, turning the lilac walls Van Gogh painted into the light blue color present in the current state (29). The chemical mechanism of this lightening and the danger posed to paintings by the carbon dioxide exhaled by humans connect topics from the conservation of French cave paintings to the manufacture of lead red and lead white. The concepts in this section relate the chemical basis of color to the biological workings of human health, and prepares students to understand articles investigating the chemical mechanisms behind fading or browning paints. J. “How Do You Put Colors Together?” A lesson on color theory can be placed earlier in the pedagogical sequence, but also fits here because of its reliance on synthetic chemistry and its artistic influence on Impressionism. The particular color wheels constructed by the dye chemist Michel Chevreul to organize the colors 102
produced by synthetic chemistry influenced many artists, including Georges Seurat (30). The scientific aspects of Seurat’s technique include systematic repetation of test canvases, which the students will follow in the lab. Seurat’s pointillism leads to a discussion of human perception of color and complementary colors. In class, students use LED flashlights to observe absorption and transmission of complementary colors through solutions of colored dyes in petri plates (31). These colors can be quantified in RGB and CIE L*a*b* coordinates and analyzed graphically (32), as the students will accomplish in a short computational project near the end of the class. K. “Is This Painting a Forgery?” Many class exercises and articles can walk students through the process of determining if a painting was truly painted by a historical artist or forged by a modern opportunist. Two such case studies were used in this class. The first was a reading describing multiple techniques used to examine a known forgery that is a painting of a village scene dated 1866 which was painted in the 20th century (33). The painting was analyzed with UV light, NIR, XRF, Raman, FT-IR, and GC-MS, introducing the students to the use of these techniques toward a clear conclusion that the painting was forged which can be applied to other cases where the forgery is uncertain. The second activity is a case study of a painting attributed to Paul Cezanne that tasks the students with the role of a museum docent deciding if the painting was forged, given multiple types of data and historical considerations of provenance (34). This case study does not have a clear conclusion so that the students must weigh conflicting evidence and come to a decision in the face of uncertainty. Either decision in this case is reasonable. Students write a paragraph summarizing their decision and the evidence for it in objective, technical language. L. “How Do I Analyze the Colors in Art Myself?” After asking the previous eleven questions, students are prepared for independent inquiry analyzing the colors in art. They choose any colorful painting and use online tools to calculate the dominant colors in its palette and convert those into CIE L*a*b* coordinates. This graphs an artist’s palette with intuitive coordinates, showing relationships and patterns among the colors such as complementarity (32). Using this protocol, we have found that both Van Gogh landscapes and Eastern Orthodox icons use distinct patterns of complementary colors that are not found in paintings by Seurat or Cezanne. This suggests that Van Gogh and iconographers used color in similar ways. The protocol is housed on the website GENI-ACT.org, which is a platform organizing research protocols and data collection for projects in the natural sciences, under the course title “Computer Analysis of Color Space Usage in Art / One-hour Color Space Analysis of an Image (35).” For this project, the protocols are entirely online and can be accomplished remotely, like gene annotation projects on GENI. This project has been carried out both in a laboratory classroom and online during the COVID-19 pandemic, supplemented with online video classroom discussion and screen-sharing as the students work. The freedom to choose one’s own research subject allowed students to anlayze diverse colorful images from all eras of art, which motivated their analysis.
Final Writing Project Most of the lectures on chemistry, history, and art are completed in the first half of class. During this time, four class sessions take place with a faculty librarian to demonstrate how to navigate the technical literature at the intersection of chemistry and art. This includes topics such as discerning 103
between a primary research article and a secondary review article, using online searches to find related articles using a particular technique, and finding the crucial parts of an article that are important for summarizing but not necessarily critiquing the results. The articles provide specific examples of chemical analysis of art, and also give the students examples of how to write in a technical, objective style. Students choose eight articles and write a paragraph-long annotation for each by the midpoint of the quarter. In the second half of the quarter, one class a week is given to a six-week sequence of making and testing pigments, and the other two classes are used for writing toward the final project. Students complete a scaffolded set of assignments which take the annotation paragraphs and edit them to form the different sections of a scientific review. The thesis for the review is that two chemical techniques have different strengths and weaknesses, leading to different uses for art analysis. Students support this thesis with detailed descriptions of examples from the scientific literature where these techniques are employed. These assignments are described in Table 1. The earlier assignments have a minimum length to encourage students to add details, while the final assignment has a maximum length less than the combined length of the earlier assignments, requiring the students to edit and prioritize what they had previously written so that it serves the thesis more completely. Students connect their lab work to the writing assignments by presenting in an oral mode at the end of class. Here they describe the painting they chose to create in the last week of lab, and hypothesize about the results they would obtain by subjecting their painting to one of the chemical analysis techniques they learned about in class. As the students display and describe their paintings, they can see a whole range of diverse, creative approaches to art, all starting from similar sets of labsynthesized pigments. Table 1. Scaffolded Writing Assignments Leading to a Comparison of Two Techniques Assignment #
Section
Word Limit
Based On
1
Annotated Bibliography draft
~250/paragraph
Lit. research
2
Annotated Bibliography final
~300/paragraph
Ann.Bib. draft
3
Abstract and Background
300 and >500
Abb.Bib. final
4
Results for first technique
>800
Abb.Bib. final
5
Results for second technique
>800
Abb.Bib. final
6
Review essay