Tree Products

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REE PROD V

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The "Reason

Why

9

Books

TREE PRODUCTS Irving

and Ruth Adler

The John Day Company

New

York

The "Reason Why" Books by Irving and Ruth Adler AIR

ATOMS AND MOLECULES COAL EVOLUTION FIBERS

HEAT HOUSES INSECTS AND PLANTS IRRIGATION: CHANGING DESERTS TO GARDENS

LEARNING ABOUT STEEL (former title: The Story of a MACHINES MAGNETS NUMBERS OLD AND NEW NUMERALS: NEW DRESSES FOR OLD NUMBERS OCEANS

Nail)

RIVERS SETS

SHADOWS STORMS

TOUCH AND SMELL THE EARTH'S CRUST THINGS THAT SPIN TREE PRODUCTS WHY? A BOOK OF REASONS WHY AND HOW? A SECOND BOOK OF REASONS YOUR EARS YOUR EYES TASTE,

Copyright All rights reserved.

or by

any means

No

©

1966 by Irving and Ruth Adler may be reprinted, or reproduced in any form mechanical or other (including but not limited to photo-

part of this book

electronic,

copying, recording, or a process of information storage and retrieval), without permission writing from the Publisher, The John Day Company, Inc., 62 West 45th

m

10036 Published n the same da ° y '

Hmit,,! Library of Congress Catalogue Card Number: Printed in the United States of America

AC

Street

in

Canada b y Longmans Canada

66-10575

Contents

A

Great Treasure

What

Is

4

a Tree?

6

Inside the Living Tree

8

The Use of Trees in Ancient Times The Use of Trees: From Ancient Times From Forest Tree into Log From Log into Lumber

11 to

1500

15 17 18

Other Uses for Logs

20

Wood Charcoal from Wood

22

24

Plywood

25

Facts about

Other Man-made Building Materials from

Wood

28

The Early History of Paper The Story of Wood Pulp

31

Paper from Chemical Pulp

35

Naval Stores

38

We Use Barks We Use Fruits We Use

40

Sap

U.

S.1386132

32

42

44

Lignin

45

Trees for the Future

46

Word

47

List

A

Great Treasure

Trees are one of our greatest treasures.

We plant trees near our homes because their leaf -covered

Their leaves

branches give us shade.

make

soft

sounds as gentle

winds blow through them. to hear these sounds.

nests in the branches It is

We

It is

pleasant

Birds build their

and hollows

of trees.

pleasant to hear the songs of birds. plant trees near our

homes because

trees are beautiful to look at.

Farmers plant blocks of

trees near their

farmhouses and barns as a protection against strong winds.

Windbreaks help

keep barns and houses warm. Farmers plant belts of trees around their Shelterbelts

fields.

keep strong winds from blow-

u

>

away the good topsoil in which farmers grow their crops. Trees that grow close together over great stretches of land make up forests. Forests are the homes of wild animals and birds. The roots of forest trees prevent ing

and keep

floods

away by heavy

soil

from being carried

rains.

Trees are a great treasure, too, because

many products we get from them or make from them. We get products such of the

as fruits, nuts

the trees are trees to

still

make

This book

from

trees

from

trees.

and saps from

is

standing.

trees while

We

cut

down

other products from them.

about the products

we

get

and the products we make

What

A

tree

is

Is a

Tree?

a living thing that belongs to the family of

plants. Its roots hold

it

firmly in the ground. It has a

The trunk is made up of many layers, one inside the other. The innermost layer of the trunk is called the pith. The outermost layer is called the bark. There are layers of wood trunk shaped like a cylinder (SILL-in-dur).

in

A

between the pith and the bark.

The crown

of a tree

is

usually

and branches. The crown

palm tell

trees,

is

made up

of

tree has a crown.

made up

some

trees,

only of leaves.

one kind of tree from another

of leaves, twigs

is

such as certain

One way we can

by the shape

of

its

crown.

There are two main families of

trees.

family of conifers (KON-uh-furs).

One

family

is

the

The other family

Needles and cone of a pine, which

is

a conifer

is

the family of broad-leaved trees.

Trees in the conifer family usually have long, thin,

needle-shaped leaves. Most conifers keep their leaves

all

year round. These conifers are called evergreens. Pine,

hemlock and spruce are examples

Some evergreen

of evergreen conifers.

conifers are used as Christmas trees.

Conifers produce seeds that have no protective covering.

The

seeds are on the scales of a cone. Conifers are

also called softwoods.

Broad-leaved trees usually lose their leaves each year

and grow new leaves the next

year. Trees that lose their

leaves each year are called deciduous (dih-SIJ-yuh-wus) trees.

Maple, oak and birch are examples of deciduous

broad-leaved

trees.

The seeds

of broad-leaved trees

have

a protective covering. Broad-leaved trees are also called

hardwoods.

Leaf and

fruit of

an oak, which

is

a deciduous hardwood

Inside the Living Tree

A

like

tree,

all

living things,

(SELLS). There are many

Each kind

of cell has

the tree alive and

its

make

made up

of cells

different kinds of tree cells.

own it

is

special job to

do

to

keep

grow. Cells are so small they

can be seen only with the help of a microscope. Cells reproduce selves

by

(

REE-pruh-DYOUS

from the ground. Certain

of the trunk carry water all

or

make

cells like

draw up water and mincells in

the

woody

and minerals from the

parts of the tree. These cells are called

lum)

them-

splitting in two.

Cells in the roots of the tree erals

)

cells.

layers

roots to

xylem (ZY-

Cells in the leaves of the tree use water, air

and energy from sunlight

to

make food

for the tree.

Some root cells have root hairs. The root hairs grow out into the soil. They

draw

in minerals and water from the soil that

them.

surrounds

6*3**sr"

Other

cells in

the trunk, on the innermost side of the

bark, carry water with food in parts of the tree.

em)

cells.

These

it

from the leaves

phloem

cells are called

The water with minerals

or food in

(

to all

FLOW-

it is

known

as sap.

A

tree

grows

in

two ways.

It

grows

in height

and

its

trunk grows in thickness.

When new

cells in

cells,

There

is

the tips of the branches split and form

the tree grows in height. a layer of cells

between the phloem and the

KAM-bee-um When cambium cells split in two and form new cells, some of these cells become new phloem cells and others become new xylem cells. In this way a new layer of cells is added to xylem called the cambium

(

)

.

Bark

Phloem

Cambium Pith

Xylem. This tree has five rings of xylem cells.

Diagram

of the trunk of a tree, cut crosswise

9

the trunk of the tree and the tree grows in thickness. This

growth mer.

If

is

faster in the springtime than

the trunk

is

it is

in the

sum-

cut crosswise, the difference between

summer growth next to it shows up as a ring around the pith. You can find out how old a tree was when it was cut down by counting the number of tree rings. Each ring stands for one year of the spring growth and the

the tree's age.

Some softwood

trees

have a network of tiny canals

running through their bark and wood. These canals are called resin

(REHZ-in)

canals. Special cells along the

make a liquid called oleoresin (OH-lee-ohREHZ-in). The oleoresin collects in the resin canals. Every plant cell has a cell wall around it. The cell wall is made up largely of tiny fibers of cellulose SELL-yuhlohss In woody plants the fibers of cellulose are held resin canals

(

)

.

together by a chemical called lignin

makes the

cell

wall

(

LIG-nin )

.

Lignin

stiff.

Count the tree

10

old

was

was

cut

rings.

this tree

down?

How

when

it

The Use

Man

of Trees in Ancient

Times

has been making things from trees and getting

things from trees for thousands of years. Earliest

man was

a food-gatherer. His food consisted

of the animals

he

berries, fruits

and nuts he

killed, the fish

with wooden spears,

trees.

He

roots,

killed animals

and throwing-sticks.

fires.

He dug up

He

roots with

He gathered nuts and fruits that Earliest man had no permanent home.

wooden digging grew on

collected.

clubs

cooked them over wood

he caught and the

sticks.

He made his home wherever he could find food. About 7,000 years ago man began to raise his own move from place to place in search of it. He settled down in one place. He built permanent shelters. He made tools and furniture. He food.

Then he no longer had

Wooden

to

throwing sticks used by ancient food gatherers 11

.

«.

Wooden implements

made about 4000 years ago

made

clothing and dishes.

of the materials

He built and made

he found nearby. Trees grew

the places

where man made

often used

wood and

and making

things out in

his settlements.

most of So

man

other tree products for building

things.

much people who

Great forests covered years ago. So the

of

Europe thousands

lived in central

of

Europe

made many things from wood. They built wooden houses.* They made wooden tables and benches. They made wooden mallets, ladles and bowls. They made dishes by sewing together pieces about 4,000 years ago built and

of birch bark. °

For more information see Houses by the same authors, The John Day Company, 1964.

12

There were no trees

palm

forests in ancient Egypt. Tall

grew well because

The

of Egypt's dry climate.

Egyptians sometimes used the long, strong leaves of the

palm

trees for

making the framework

of their houses.

They covered this framework with river mud. Because there was almost no rain, these dried mud houses lasted a long time.

The Egyptians

also

wove mats and

baskets

out of palm leaves. Other kinds of trees also grew in

Egypt. But these trees were small and produced

Some

wood was used

wood

for

mak-

ing hoes and plows. Sometimes the Egyptians used

wood Then

of a poor quality.

of poor quality for

they covered the of gold.

cause

of this

making furniture and

wood with

The Egyptians had

wood

of

statues.

plaster, paint or thin layers

to

import good wood. Be-

good quality was

scarce, the Egyptians

This Egyptian statue

is

more than 3000 years It is made of wood,

old.

and

is

painted black and

The eyes are of colored stone. The gold.

claws are of

silver.

Peg

Two ways wood

-«

Peg

the ancient Egyptians joined small pieces of

learned to piece together small pieces of good wood,

They learned how

make plywood by gluing together thin layers of wood. They made many beautiful objects this way. The ancient Egyptians discovered that wood with resin in it burned slowly and very well. They made torches from resinous woods. The ancient Egyptians knew how to preserve joining

them very

carefully.*

to

animal hides by tanning them. Tanning changed the hides into leather. b

ning*

Oak

The Egyptians used oak

galls contain a lot of

galls for tan-

tannin (TAN-in), a

chemical that preserves hides.

The most important tree that grew in ancient Iraq was the date palm. It is still Iraq's most important tree. The people who lived in ancient Iraq used the date palm in hundreds of ways. They made furniture from its wood. They used its leaves for making ropes and mats. They ate its fruit. They also made wine from its fruit. They made charcoal from its fruit pits. They pounded the pits into

meal that they used

as flour

and

as food for cattle.

* For more information see Learning about Steel through The Story of a Nail by the same authors, The John Day Company, 1961. *° For more information see Insects and Plants by the same authors, The John Day Company, 1962.

14

A

chair

The

made 700

legs,

years ago.

arms and back were

turned on a lathe.

The Use During

of Trees:

this

From Ancient Times

to

1500

period people developed better ways of

wood and other tree products. They also developed new uses for wood and invented new tree products. Woodworkers learned how to bend wood by steaming it. Long flat pieces of bent wood were used for making

using

barrels.

Wood was

of chairs.

bent for making the backs and legs

Woodworkers

also learned

LAYTHE

Small pieces

on a lathe

(

)

.

how to turn wood of wood of a very

good quality were turned. They were used of chairs

as the legs

and couches. Woodworkers learned how

to

improve the quality of the wood they used by seasoning it.

The growing

up through out.

its

tree contains a lot of

roots.

Some wood

Freshly cut

also cracks

woodworkers learned how

if it

wood

it

shrinks as

draws

it

dries

dries too quickly. Early

to dry 15

water that

wood

slowly, or season

it,

before they used

it.

One way

by removing the bark from still

they seasoned

wood was

trees while the trees

standing. This exposed the water-carrying

to the air.

The

air

slowly dried

were

phloem

up the water.

many new industries developed. People learned how to make glass and developed better ways of making metals. Glass and metals were made in During

this

period

furnaces at very high temperatures. Charcoal was the fuel for these high-temperature furnaces. Charcoal

was

made from wood. During

Wood Oak

this

period people learned

how

to

make

soap.

ashes were used in soapmaking. galls

continued to be used for tanning leather.

Charcoal, a fuel made from wood, was used to heat the furnaces in which glass was made. 16

From As a

tree grows,

sunlight.

So

it

A

Forest Tree into its

forest tree

A

grows very close

forest tree

a long, straight trunk. trees

leaf-covered branches reach for

cannot spread outward.

for sunlight.

can be

made

The production

The

grows

is

room

way

for the

in height

and develops

of logs begins in the forest.

some

In this

can only reach upward

long, straight trunks of forest

which

trees are to

be

There a

some

cut. In

of the trees are selected for cutting.

These are usually the oldest fects.

It

to other trees.

into logs.

tree expert decides forests only

Log

the forest

younger

space for planting

new

trees or trees that is

thinned out so that there

trees to trees.

grow

well.

There

In the Douglas

however, whole blocks of trees are cut

Block-cutting of Douglas 17

have de-

down

fir

trees

fir

is

also

forest,

at the

same

A logger tree

cuts

down

a

with a power saw.

A

logger saws the tree up into logs. This is called bucking.

Douglas firs

of trees,

baby

are planted. In the cleared block the

baby

As soon

time.

firs

as the block has

can get the

full

been cleared

sunshine that they need in order to

grow.

Men saws.

called loggers cut

They

cut

them

down

as close to the

Then they remove all saw the trunk up into

is

They may be

ground

power

as possible.

the branches from the trunk and logs.

This

logs are then taken to a mill for use.

the trees with

is

called bucking.

where they are prepared

carried to the mill

a river nearby, the logs

may be

to the mill. 18

The

by

truck. If there

floated

downstream

From Log into Lumber are to be made into lumber

Logs that sawmill.

A

conveyor chain carries the logs to the top of

Each

a sloping platform on the sawmill floor. is

rolled

down

log carriage.

The

and forth along a

carriage rolls back

trimmings, called slabs, are carried

Then

log in turn

the slope and placed on the platform of a

metal track to a saw that trims the bark

belt.

are taken to a

the trimmed logs are

off

off

sawed

the log. These

by

a conveyor

into

rough lum-

ber.

Next, the rough lumber

which cuts with

its

off

is

carried to an edger sate

the lumber's rough edges.

edgings cut

off, is

wim

then cut into boards of

different lengths.

differ-

The edger saw cuts off the lumber's rough edges.

Trimmer saws cut the lumber into boards of

The lumber,

Wood

away at this time. The trimmed boards are placed on a pair of moving chains. As the boards are carried along by the chains, they are sorted by quality. The next step in preparing lumber for use is seasoning it. Some lumber is stacked out in the open air for seasonent lengths.

with defects in

it is

cut

KILLS

Other lumber

is

seasoned in dry kilns

a dry kiln, hot air

is

circulated around stacked lumber.

ing.

Lumber

that

is

kiln-dried can

may

Open-air seasoning

woods usually take longer

be seasoned

it is

in a

)

In

.

few days.

take several months.

Hard-

to season than softwoods.

The seasoned lumber then goes where

(

to a planing mill,

given a smooth surface. In the planing mill

the seasoned lumber

is

made

into flooring, siding, mold-

ing and other kinds of boards. Slabs, edgings

wasted. Sawdust factories that

and pieces is

make

of

wood with

not wasted either. other

defects are not

They

are sold to

wood products from them.

Other Uses for Logs Railroad tracks are supported by crossties. Crossties

wooden beams

may be made from

ern pine or Douglas

fir.

logs of oak, south-

Since crossties rest on the ground,

moisture from the ground makes them longer

if

Creosote

called

rot.

They

last

they are painted with a wood-preserving (

KREE-uh-soat )

is

20

a good wood-preserving

oil.

oil

that

is

made from

Telephone and

coal.

electric poles are

logs of southern pine that

preserving

Wood into

made

oil.

piling

is

driven into the floor of the ocean or

swampland and

100

from

have been treated with a wood-

bottoms to support

river

road bridges and even buildings. Piles as

chiefly

feet. Piling

pine and Douglas

is

fir

made mostly from that have

piers, rail-

may be

as long

logs of southern

been treated with a pre-

servative.

Smaller logs are

made

into fence posts.

Fence posts

are often treated with preservatives. Large branches are

cut into logs for firewood.

Logs are

also

made into wood pulp and plywood. See (

pages 25 and 32.)

These posts have

just

been treated with creosote. 21

Facts about

Telephone and

Wood

strong to be able to support the wire that

made from Douglas

them. Poles

are strong. Utility poles der.

Douglas

fir

must be

electric poles (utility poles)

must be

fir

is

strung from

and southern pine

tall,

straight

and southern pine produce

and

slen-

straight

tall,

bend a little in strong winds without breaking. Wood can bend and come back to its original shape. For this reason, we say slender logs. Utility poles must be able to

wood is elastic (uh-LASS-tick). So utility poles are often made of wood. Wood piling and railroad crossties the

must

also

Wood

be strong and

is

elastic.

light in weight. Its lightness

handle without very heavy ter

can easily

Balsa ness

wood

it

is

lift

the

lifting

wood he

makes

equipment.

it

A

carpen-

uses for building a house.

the lightest of woods. Because of

its

has been used for making airplane wings.

Maple

Walnut 22

easy to

light-

Wood

does not change

its

temperature quickly with

quick changes in the temperature of the

wood feels warm to wood is used a lot for So

do not

furniture.

is

around

it.

why wood

one reason

Houses made

of

lose their heat quickly in the wintertime.

Some wood is

the touch. This

air

is

easy to work with a carpenter's

easy to turn on a lathe. This

and cabinetmaking. furniture

Wood

made

direction in

in the

which

its

is

good

for furniture

with a nice grain

and cabinetmaking,

the pattern

wood too.

The

tools. It

is

grain of

good

for

wood

is

wood by its growth rings and the wood cells grow. The grains of

maple, walnut, oak and cherry are shown below.

Some wood has unusual qualities that give it special uses. The tree lignum vitae (LIG-num VY-tee) is very hard. Moving parts made from it never need oiling. It is used to swells

line the propeller shafts of ships.

when

it

gets wet, so

it is

Oak

used

Teak hardly

in shipbuilding.

Cherry 23

Wood

Charcoal from

When wood burns the

wood produce

in the

open

gases driven out of

air,

flames and smoke. After the gases

have burned up, the flames and smoke die down. The

wood wood

shrinks is

and turns

black. This wrinkled charred

charcoal. It burns with almost

gives off a great

amount

burns up and the

fire

Burning wood

no smoke and

of heat. Finally the charcoal

goes out.

open

in the

air is

not a good

way

to

make charcoal, because then the charcoal burns up, too. One way of making charcoal is by burning wood very slowly in a kiln. The wood burns slowly because hardly any air passes through the kiln. The slow burning forces the gases out of the wood. The gases do not catch on fire but pass out through an opening in the

were made by covering a kilns

were made

of brick.

pile of

kiln.

wood with

They were

Early kilns

earth. Later,

called beehive kilns,

because of their round shape. Small portable beehive kilns

have been made of sheet metal. Kilns are made of

concrete and fieldstone, too.

Charcoal (

is

usually

made now by

C AR-bun-ih-ZAY-shun

in

an

airtight

Baking drives

made

oven and off

)

method. The wood

is

baked

at a

is

placed

high temperature.

the gases, which are collected and

wood by-products. The baked wood becomes The carbonization method of making charcoal

into

charcoal.

the carbonization

24

^^^{gi^54*^^^

Charcoal making 400 years ago. The man is heaping logs on the pile at the right. The pile at the left is covered with earth. The wood inside this pile is burning slowly. is

better than the kiln method. It takes less time than the

kiln

method. The gases and

tars are

made into other products. One of the most important

uses of charcoal today

as a cooking fuel for barbecues.

cues

make

is

usually

made

briquettes,

first

not wasted but are

Charcoal used in barbe-

into briquettes

a paste

is

is

(bri-KETS). To

made from crushed wet

Then the paste pillow-shaped briquettes by a press-

charcoal and cornstarch or potato starch. is

formed

into small,

ing machine.

The wet

briquettes are then dried in an

oven.

Plywood

The Egyptians made plywood because they had very little beautiful wood. They were able to produce beautiful wood surfaces for cabinet work by gluing a thin sheet 25

(vih-NEAR)

or veneer

to a piece of ordinary

make plywood

of

wood with

a beautiful grain

wood. Like the Egyptians, we

to put a nice

also

veneer surface on ordinary

wood.

We

make plywood because plywood has many that lumber does not have. Plywood is made

also

qualities

by gluing together three or more

The

grain of each ply

next to ing.

it.

laid across the grain of the plies

is

usually

made with an odd number

of

(WARP-ing)

or

This keeps plywood from warping

bending by

itself.

formed more to use for

wood

is

wood.

This keeps plywood from swelling and shrink-

Plywood

plies.

is

plies or layers of

However, plywood can be shaped and

easily than solid

curved surfaces

much

ness. Panels of

wood. This makes

like chair

backs and

good

it

seats. Ply-

stronger than lumber of the

same

plywood can be made much

larger than

pieces of lumber

sawed from

logs.

thick-

This fact makes build-

ing with plywood faster than building with lumber.

The tree

is

story of

cut

plywood begins

in the forest

down and the trunk is trimmed

At the plywood factory the trunk will is

fit

is

of

off

the logs and the logs

makes veneer cutting on a rotary of veneer

lathe.

comes

easier.

The off

branches.

cut into lengths that

into the veneer-cutting machines.

taken

its

where the

may be

Then

the bark

heated. Heating

Most veneer cutting

picture shows

how

is

done

the thin sheet

the log as the log turns against the 26

Log on a rotary

lathe

The

cutting blade of the lathe.

sheet of veneer

cut into pieces. Pieces with defects are cut time.

The trimmed

is

away

then

at this

pieces are dried. After drying, the

pieces are joined together to

make

full-size sheets of

veneer. Both sides of each veneer sheet are then coated

with glue. Waterpoof glue that

is

to

is

used for making plywood

be used outdoors. The glued sheets are assem-

bled so that the grain of each sheet grain of the sheets next to are placed in a hot press.

hot press

make

is

laid across the

Then the assembled The heat and pressure it.

sheets of the

the glued sheets stick to each other,

forming a plywood panel. After the plywood panel leaves the press,

it is

sawed

to the right size

and sanded.

Panels are usually sawed so that they measure 4 feet by 8 feet. Panels measuring 40 feet have been special purposes.

27

made

for

Other Man-made Building Materials from

Wood

(LAA-mu-NATE-id) wood — Laminated wood is wood that is made by gluing together many layers of wood. The grains of the layers usually lie in the same direction. Each layer is made up of many small pieces of wood that have been glued together. The pieces of wood are seasoned before they are glued. This keeps laminated wood from cracking and shrinking. Using lamLaminated

inated wood, great arches and rafters for supporting roofs can

be made from small pieces of wood. Some of

these arches are

more than 150

— Hardboard

feet long.

man-made board made from wood fibers. The fibers are made by exploding wood chips with steam. The fibers are made into a wet mat that has about the same size as the finished hardboard panel. The wet mat is then placed in a hot press where heat and pressure press the mat of fibers into a thin hard sheet. The fibers are held together by the lignin in them. Because hardboard is made from wood chips, hardboard can be made from healthy pieces of wood of Hardboard

any

size.

a

Sawmill trimmings are often used

hardboard. Hardboard also

is

is

in

making

used as a wall paneling.

It is

used for making cabinet backs, drawer bottoms and

counter tops. Particle

(

P AR-tih-kul board )

28

— Particle board is a build-

Laminated wood used making the head of

for

a golf club

Laminated wood arches

Papreg

in

tube form

sheet and

.

ing material that

made from

is

are held together

by

wood

small bits of

that

which they have

a chemical with

been mixed. Particle is

board

faced with

used as a wall paneling. Sometimes

is

wood veneer or hardboard. Wood

sawdust and other sawmill leftovers are used

it

shavings, in

mak-

ing particle board.

Modified (MOD-ih-fide) tcoods

means

to change.

Wood

crack, shrink, swell,

when

it

ture.

Wood

gets

cells

modified so that

or

change

ing pressed at the

with a

Wood

same time

is

is

in

will not

way

tempera-

empty spaces

Modified

resin.

that

wood

When

which has been

modified without be-

called

impreg

(

IM-preg)

layers of veneer are modified is

called

under heat

compreg (COM-

and knife handles are sometimes made out

preg. Tool

compreg.

If

sheets of paper are treated with resin

then modified under heat and pressure, a product sults that is

known

as

is

used for making patterns for automobile

is

and pressure, the product

of

the

filling

it

shape in any

its

of veneers, each of

treated with a resin.

bodies.

is

modified by

is

made up

Impreg

word "modify"

wet or when there are changes

around the wood usually

warp

— The

very strong and

is

papreg (PAY-preg).

tubes and pipes.

It is

and re-

lighter than metal. It It

is

can be bent to form

used for paneling walls and coun-

ter tops.

30

The tub is filled with a mixture of water and shredded rags. A thin layer of rag pulp covers the screen. The man shakes the screen while the water drains

off.

Making paper by hand 400 years ago

The Early History

of

Until about 150 years ago paper

Paper

was made by hand

way the Chinese had made it 2,000 years earlier. It was made mostly from linen and cotton rags and cloth. The rags and cloth were shredded and beaten into a pulp of linen and cotton fibers. The pulp was then mixed the

with water.

A thin

layer of the

a wire screen and the water

wet pulp was spread over

was allowed

to drain off.

The screen was shaken while the water was draining to make the linen and cotton fibers stick together to form a mat. When the thin layer of matted fibers had dried, it was a piece of hand-made paper. Making paper by hand took a lot of time. So paper was very expensive and not very much was made. The first paper-making machine was invented in 1798. Even though paper could then be made in less time, there

was

a shortage of paper because linen

still

The paper shortage ended making paper from wood was dis-

and cotton rags were

when

a

covered.

method

of

scarce.

The Story

of

Wood

Pulp

The first step in making paper from wood is to make wood pulp. Wood pulp is wood that has been broken

a

down

so that

its

cellulose fibers are separated.

made from the softwoods — pine, spruce, hemlock and fir. It is made from sawed logs and from sawmill slabs and other trimmings. The first step Most wood pulp

in

pulp-making

is

is

to

remove the bark from the

logs.

There are three ways of making wood pulp. Each

own kind of paper. One way of making wood pulp is by cooking

method produces

its

the

wood

with certain chemicals. First the peeled logs are cut into

The wood chips are then placed in a huge vat called a digester. The digester cooks the chips and chemicals under pressure. The chemicals dissolve the lignin and resins in the wood. The chemicals, lignin and small chips.

removed, leaving a pulp of almost pure

resin are then

cellulose fibers.

Pulp made

pulp. Chemical pulp

is

in this

made

also

A

is

for books.

Chemical pulp

used for making plastics and man-made

second way of making wood pulp

peeled logs of stone.

called chemical

into good-quality writing

and wrapping paper and paper is

way

The

wood under water

cellulose fibers are

is

by grinding

against a rough grind-

ground

off into

along with the lignin and the resins. Pulp *

*

fibers.

the water

made

in this

For more information see Fibers by the same authors, The John Day Company, 1964.

32

Wood at a

Peeled logs on the way to the chipper

Chips being carried

to

^

|fe»

X

the digester

Digester

Making chemical pulp

1^

for pulp arriving paper mill

way

is

called groundtvood pulp, because chemically

no different from wood.

called mechanical pulp

made by the mechanical method of grindPaper made from mechanical pulp is very weak.

because ing.

It is also

it is

it is

Newsprint, the paper on which newspapers and some

made mostly from mechanical chemical pulp is added to make the news-

magazines are printed,

A

pulp.

little

is

print stronger. Newsprint

A

way

is

a very inexpensive paper.

making pulp

partly chemical

and

partly mechanical. Peeled logs are cut into chips.

The

third

wood

of

chips are softened a

little

is

by cooking them with

mild chemicals. The softened chips then pass between a pair of quickly spinning plates that

pulp. Pulp (

made

Semi means

change them into

way is called semichemical pulp. Many kinds of cardboard cartons are

in this

half.

)

made from semichemical

pulp.

Paper

fiber

tubes

made from chemical

m

pulp

A

pulp beater

y. S. 1386i3 ;>

Paper from Chemical Pulp Before pulp

is

made

into paper,

it

must be thoroughly

washed, cleaned and screened. The pulp spraying of a

huge

it

with water as

cylinder.

it

is

washed by

turns around on the outside

Washing removes any chemicals and

other materials that stick to the cellulose fibers after they leave the digester. Cleaning and screening remove dirt

and uncooked wood chips and separate the

fibers

by

Then the pulp is bleached to make it whiter. The pulp now passes on to a large tank called a beater. Water and pulp are mixed together in the beater. If the size.

35

A

mixture of water and pulp

The dried paper

is

is

run onto a moving screen,

wound up 36

in

a huge

roll,

pulp

is

being

made

into colored paper,

dye

is

added

to

the mixture in the beater. Certain chemicals are also

added

to the mixture in the beater to size paper. Sized

paper doesn't soak up liquids

on with pen and

ink.

easily, so

it

can be written

The pulp may then go on

The refiner rubs and them shorter. Shorter

to a re-

finer.

cuts the cellulose fibers,

ing

fibers

When finer,

as

more water

is

added

until the mixture has

as pulp. This

watery mixture then goes

onto a long, wide moving belt,

made

As the screening moves along

side to side.

together in drains

The

run

of fine wire screenit

also shakes

from

The shaking makes the cellulose fibers stick a mat. At the same time, some of the water

sheet of wet pulp

is

carried through

many

pairs

which press out more water. Next the sheet

travels over a series of hot cylinders

A

is

off.

of rollers

ing.

99 times

paper-making machine. The mixture

to the

ing.

finer paper.

the mixture of water and pulp leaves the re-

much water

on

produce a

mak-

half-mile of paper

in a minute.

may

finish the dry-

pass through the dryers

wound up in a roll. Rolls paper-making machine may measure 25

The dried paper

that leave the

which

is

feet across.

The

large paper rolls are usually cut into smaller rolls

or into sheets before they are sold. 37

Naval Stores In the days of

wooden

sailing ships, supplies of tar

always had to be on hand. Cracks between the wooden boards of a ship were waterproof.

with tar to

The ropes that held up the sails were treated keep them from rotting. Because tar and

products related to in

it

were used mostly

has

many

Naval

resin

keeping ships

leaf

and

produced by

is

woody

and pan are nailed

which grow

layer

is

The

South are the

A

to the tree just

still

standing

long, crosswise slash is

removed and

A

layer of tree shows.

metal gutter

under the

slash.

Then

sprayed with an acid. The acid makes

the gutter into the pan.

made about

steady flow of gum. barrels

States the long-

in the

slashed bark

the oleoresin begin to flow.

ones, are

made from

of oleoresin.

in the bark.

woody

are

collected from trees that are

the outermost

the

They

trees in the pine family. Oleo-

without damaging them much.

made

This

called naval stores even though

gum. In the United

slash pines

main sources

Gum

stores.

other uses today.

also called

is

is still

stores are tree products.

oleoresins

is

for

good condition, they were called naval

family of products it

with tar to keep the ship

filled

New

The

slashes, just

down

above the old

every two weeks to keep up a

The gum

which are taken

oleoresin flows

is

collected in

to a distillation

38

(

wooden

DISS-tuh-LAY-

shun) plant.

Gum

from the stumps of resinous

have been cut down

is

also gathered to

trees that

be used

for

mak-

ing naval stores.

The

chief products

made from and

tion plant are turpentine for thinning paint. It

Turpentine is

used to

violin

is

also

is

used

size paper. It

bows

to

oleoresin at the distilla-

rosins.

Turpentine

used in making paste

used

waxes.

making some medicines. Rosin

in is

floor

is

rubbed over machine

keep them from

belts

and

sticking. Baseball players

rub rosin over their hands so their hands won't stick to the bat or the ball. Rosin

and printing

inks.

Gutter and pan for collecting oleoresin

Spraying with acid to make the oleoresin flow

is

also

used

in

making paints

Sap Before the white

knew

We

Use

man came

North America, the

to

wounds in certain maple trees had a sweet taste. They even knew how to make sugar from the sap. Today the maple sugar Indians

industry

that the sap that flowed from the

an important farm industry in the North-

is

eastern part of the United States.

the industry

The raw material

of

the sap of the sugar maple or the black

is

maple. In the sugar maple and the black maple, sap

moves

through the xylem in the springtime under great pres-

The pressure

sure.

in the

than the pressure of the tree. If a

hole

is

made

xylem

time

at this

air against

is

greater

the outside of the

into the xylem, the sap will flow

through the hole to the outside. Farmers make use of fact

when they

tap maple trees in the early spring.

Farmers tap maple the xylem.

A

this

trees

by

drilling a

few holes

metal spout, sometimes called a

into

spile, is

placed in each taphole. The spout works like an open faucet through which the sap can flow.

hung under each spout

bag

is

The

pails or

The

it is

to catch the flowing sap.

collected sap

made

products. In very

many

pail or plastic

bags are emptied several times a day into

large buckets.

house where

A

is

taken to the sugar-

into syrup, sugar

and other maple

modern sugar bushes (woods with

sugar or black maples ) the sap 40

is

pumped through

Hanging a

pail

under a spout

Bringing the sap to the sugar house 41

plastic tubing

from the taphole right

In the sugarhouse the sap in the sap

thicker.

is

driven

The

sap,

As

which was pale yellow

Maple syrup

syrup.

boiled.

boils,

it

water

and the sap becomes sweeter and

off

brown. The sap

light

is

to the sugarhouse.

is

boiled until

it

in color, turns

becomes a thick

used as a flavoring. Further

is

boil-

ing produces a thicker mixture which can be used as a spread.

what in

When

is left is

almost

maple

molds or cut

all

the water has been boiled

sugar.

Most bark.

trees

The

We

candy.

Use

form a layer of cork on the outside of the

waxy

walls of the cork cells have a

material in them. This

and

Maple sugar can be shaped

like fudge. It is a

Barks

airtight.

off,

makes the cork

The cork oak

cells

or fatty

waterproof

that grows in countries near

Cork when

is

stripped off

the cork oak

about 25 years

is

old.

New

cork cells grow forming new layers of cork.

These new

lay-

ers are stripped off every 9 years.

42

the Mediterranean Sea produces very thick layers of cork. Its cork cells are filled with air.

of the cork

oak

cause the cork

and

airtight,

made

is

many

into

cells are filled

with

Cork from the bark

useful products. Be-

air

and are waterproof

cork floats easily in water. So pure cork

used to make

life

jackets

makes cork a good

and

floats.

The trapped

air

Cork

insulating material, too.

is

is

crushed and mixed with other materials to make insulation

board and

floor tile.

The cork cells in the bark of some trees have tannin in them. The bark of the hemlock, chestnut oak and quebracho (key-BRAH-cho) has a lot of tannin in it. The extracted from the bark of these trees and

is

used for tanning leather. Tannin for making leather

is

tannin

is

also extracted

from the wood of the chestnut and the

quebracho and from the leaves of the sumac.

The bark

cells of

liquid called latex

may be

tapped.

(

The

some

trees

L AY-tex latex

is

)

.

produce a

sticky,

milky

Trees that produce latex

then gathered and

is

manu-

factured into rubber/

The

outside bark of the cinchona (sin-KO-na) tree

that grows in the

Andes Mountains

contains a chemical called quinine is

(

in

South America

KWY-nine

)

.

Quinine

used as a drug to treat the disease malaria. The white

pine, cherry

and witch hazel are some other

trees

whose

barks are used for making drugs. *

For more information see Fibers by the same authors, The John

Day Company,

1964.

Walnut

Apple

Some

fruits

we

each

eat. Part of

away

cut

fruit is

to

show

the seeds.

We

Fruits

The its

fruit of a tree

is

Use

the part of the tree that contains

seeds.

In a conifer, the fruit

the cone.

is

conifer are on the scales of the cone.

decorations. Craft shops use

them

for

The

seeds of the

Cones are used

making

as

novelties.

Cones are used on Christmas wreaths. In a broad-leaved tree, the fruit consists of a seed or a

group of seeds with

its

the protective covering

protective covering. Sometimes is

fleshy, as in the apple, the

cherry, the orange or the peach. fleshy coverings.

We

eat

some

of these

Sometimes the protective covering 44

is

hard and stony or woody. These hard as nuts.

We

some

eat the seeds of

Oils are extracted or taken out oil,

fruits are

nuts.

from

fruits.

Coconut

extracted from the fruit of the coconut palm,

in

soapmaking. Oil from the

is

used for making candles. Oil from the

cacao (kuh-KAA-oo) tree butter and cocoa. Olive

the olive tree. Olive

cooking

oil.

also

It is

fruit of the

made

is

oil is

African

used

is

oil

palm

fruit of the

into chocolate, cocoa

extracted from the fruit of

used as a salad

oil is

known

oil

and

as a

used in the manufacture of some

soaps and drugs.

Lignin

For the papermaker, lignin dissolved and will

be made

removed

is

a nuisance.

It

must be

to free the cellulose fibers that

into good-quality writing

and book paper.

Lignin that has been separated out in papermaking is

made into

useful products.

lignin useful in the

Its

binding properties make

manufacture of cement products and

animal-feed pellets. Lignin that has been separated out

oil wells.

Lignin in the

muds that are used in drilling muds keeps the drill points from

sticking.

Lignin

used

in

papermaking

is

added

is

also

to

Artificial vanilla flavoring

in leather tanning. is

made from

lignin.

Re-

cently a chemical containing lignin has been used as a

drug.

The drug

is

used as a

painkiller.

45

Trees for the Future

One

half of the land area of the

ered by forests.

Now

world was once cov-

only one third of the land area has

man

a forest cover. Forests have disappeared because

has been thoughtless.

he burned

Man

forests to clear

has been thoughtless

them

when

Man

for grazing.

has

been thoughtless when he cut down

trees to clear fields

new

trees in their place.

for

farming and has not planted

As a

result of

man's thoughtlessness,

do not have enough

trees to supply their

lumber and other

tree

enough

products.

trees to prevent floods

many

countries

needs for paper,

They do not have

and conserve

their supply

of water.

In countries that

still

have a good forest cover, the

people must use their forests wisely. They must plant more trees than they cut down to provide tree products .;***

for their

growing populations. In countries where

forests

have been destroyed by thoughtless burning, clearing

and grazing, the

first

task

is

great tree planting programs.

to rebuild the forests

Then

the world will have

a forest cover that can meet the needs of of the

by

all

the people

world for tree products. Then the world will have

a forest cover to help prevent floods

water supply.

and save the world's

Word

List

Cambium (KAM-bee-um) — A

layer of cells just under-

neath the phloem from which

phloem Cellulose

up the

cells are (

formed.

SELL-yuh-lohss )

cell

new xylem and new

— The tiny fibers

wall of a plant

Conifer (KON-uh-fur)

—A

that

make

cell.

tree that produces

its

seeds

on cones. Conifers are usually evergreen. They are

also

called softwoods.

Cork

—A

layer of cells

on the outside of the bark. The

walls of cork cells have a

them

makes cork

that

waxy

cells

waterproof and

Deciduous tree (dih-SIJ-yuh-wus) leaves each year

Fruit

— The

airtight.

— A tree that loses

and grows new leaves the next

its

year.

part of a plant that contains the seeds.

Lignin (LIG-nin)

woody

or fatty material in

— The chemical inside the cell wall

of

plants that holds the fibers of cellulose to-

gether.

Phloem

(

FLOW-em — A )

layer of cells inside the stem

that carries sap from the leaves to

all

parts of the tree.

— A chemical that preserves hides. Veneer (vih-NEAR) — A thin sheet of wood. Wood pulp — Wood that has been broken down so that Tannin (TAN-in)

its

cellulose fibers are separated.

Xylem

(

ZY-lum )

carries sap

—A

layer of cells inside the stem that

from the root

to all parts of the tree.

9^*

About the Authors

Ruth Adler have

Irving and

written

more than

sixty

books about science and mathematics. Dr. Adler has

been an instructor sity

and

of the

at

in

mathematics

Columbia Univer-

at

Bennington College, and was formerly head

New York City high

mathematics department of a

school. Mrs. Adler,

who

formerly taught mathematics,

science and art in schools in the

New

York

area, recently

also taught at Bennington. In addition to

working with

her husband writing this book, she has joined with him

on 26 other

titles in

the Reason

the illustrations for most of

other books written

Why

them

series

and drawn

as well as for

many

by him.

Books by Irving Adler alone and books by him collaboration with

Ruth Adler have been printed

different foreign editions, in 14 languages

and

in

in

83

in 10 re-

print editions.

The Adlers now

live in the

Town

of Shaftsbury, near

Bennington, Vermont.

PHOTOGRAPH CREDITS Pages 19, 27, 29, 32, 36 - American Forest Products Industries Page 42 — Armstrong Cork Company Pages 1, 10, 17, 18, 21, 22, 23, 29, 34, 35, 38, 39, 46, 47 - U.S. Forest Service Page 41 — Vermont Development Department

48

The

WHY

REASON

Books

by

Irving

and Ruth Adler

"They are excellent"— New York Herald Tribune

"The best of the matter is that, with authors like the Adlers, their name is a guarantee. One can be certain that not only is the exposition clear and logical, but that the scientific — The Horn Book Magazine matters presented are correct and up-to-date."

EVOLUTION "The Adlers present

their

all

books with great

young readers

simplify difficult matters for

.

.

.

scientific

accuracy and have the ability to

Well presented and

interesting."

—Catholic Library World

COAL "Described in this interesting, well -written text are the uses, origin, mining processes, and chemistry of coal. Pictures of methods and equipment are particularly useful." —Library Journal

THINGS THAT SPIN "A

helpful

— The Horn Book Magazine

and stimulating book."

SHADOWS "An

easily

understood explanation of the causes and uses of shadows."

—ALA Booklist

NUMBERS OLD AND NEW "A

fascinating book for the student interested in mathematics."

—American Library Association "Exceptional book about

how we came to count as we do." —Child Study Association of America

WHY? A "I'd suggest that

it

be given

to a child

collecting unrelated facts."

Book of Reasons with an inquiring mind and acquisitive instinct for —Virginia Kirkus

AND PLANTS

INSECTS "The

interrelation of plants

trations in

two

and

insects, for the

colors."

middle grades. Attractive and useful illus—The Horn Book Magazine

ATOMS AND MOLECULES "Successfully aiming at the eight-to-ten -year-olds, the Adlers introduce chemical symbols

and chemical formulas

.

.

.

even a

bit of

nuclear chemistry."

—The Horn Book Magazine

FIBERS uch needed, factual book on wool, rubber,

silk, fiberglass,

and man made, this includes flax, cotton, and numerous other less common ones." —Library Journal

fibers, natural

nylon, rayon,

HOUSES "In keeping with others in the series, this survey of dwellings simple. Recommended."

_,

JOHN DAY,!

*

CMMNTCE9 o

is

comprehensive, clear and —Libraru Journal