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A MANUAL OF SHOEMAKING




[Illustration: An Old-Fashioned Shoemaker. _Frontispiece._]




                                A MANUAL
                                   OF
                               SHOEMAKING
                                   AND
                           LEATHER AND RUBBER
                                PRODUCTS

                                   BY
                            WILLIAM H. DOOLEY
                PRINCIPAL OF THE LOWELL INDUSTRIAL SCHOOL

                              _ILLUSTRATED_

                                 BOSTON
                       LITTLE, BROWN, AND COMPANY
                                  1912

                           _Copyright, 1912_,
                     BY LITTLE, BROWN, AND COMPANY.

                         _All rights reserved._

                       Published, September, 1912.




PREFACE


The author was asked in 1908 by the Lynn Commission on Industrial
Education to make an investigation of European shoe schools and to assist
the Commission in preparing a course of study for the proposed shoe
school in the city of Lynn. A close investigation showed that there were
several textbooks on shoemaking published in Europe, but that no general
textbook on shoemaking had been issued in this country adapted to meet
the needs of industrial, trade, and commercial schools or those who have
just entered the rubber, shoe, and leather trades. This book is written
to meet this need. Others may find it of interest.

The author is under obligations to the following persons and firms for
information and assistance in preparing the book, and for permission
to reproduce photographs and information from their publications: Mr.
J. H. Finn, Mr. Frank L. West, Head of Shoemaking Department, Tuskegee,
Ala., Mr. Louis Fleming, Mr. F. Garrison, President of _Shoe and Leather
Gazette_, Mr. Arthur L. Evans, _The Shoeman_, Mr. Charles F. Cahill,
United Shoe Machinery Company, Hood Rubber Company, Bliss Shoe Company,
American Hide and Leather Company, Regal Shoe Company, the publishers of
_Hide and Leather_, _American Shoemaking_, _Shoe Repairing_, _Boot and
Shoe Recorder_, _The Weekly Bulletin_, and the New York Leather Belting
Company.

In addition, the author desires to acknowledge his indebtedness to the
great body of foreign literature on the different subjects from which
information has been obtained.




CONTENTS


                                                        PAGE

    PREFACE                                                v

    CHAPTER

       I. FUNDAMENTAL SHOE TERMS                           1

      II. HIDES AND THEIR TREATMENT                        4

     III. PROCESSES OF TANNING                            21

      IV. THE ANATOMY OF THE FOOT                         77

       V. HOW SHOE STYLES ARE MADE                        93

      VI. DEPARTMENTS OF A SHOE FACTORY                  103

     VII. MCKAY AND TURNED SHOES                         144

    VIII. OLD-FASHIONED SHOEMAKING AND REPAIRING         162

      IX. LEATHER AND SHOEMAKING TERMS                   177

       X. LEATHER PRODUCTS MANUFACTURE                   218

      XI. RUBBER SHOE MANUFACTURE AND TERMS              228

     XII. HISTORY OF FOOTWEAR                            250

          INDEX                                          281




LIST OF ILLUSTRATIONS


    An Old-fashioned Shoemaker                 _Frontispiece_

                                                 FACING PAGE

    Names of the Different Parts of Foot Wear              2

    Green-salted Calfskin                                 12

    Tanning Process                                       24

    Tanning Process, showing Rotating Drums               28

    Sole Leather Offal                                    34

    Bones and Joints of the Human Foot                    78

    The Different Parts of the Foot and Ankle             78

    A Last in Three Stages of Manufacture                 98

    A Modern Shoe Factory                                104

    A Skin Divided before Cutting                        112

    Cutting Leather                                      116

    Goodyear Stitching                                   116

    Stock Fitting Room                                   120

    Lasting                                              124

    Welting                                              124

    Rough Rounding                                       128

    Edge Trimming                                        128

    Leveling                                             132

    Heeling                                              132

    Sole Scouring                                        136

    Heel Shaping                                         136

    Ironing                                              140

    Packing                                              140

    Cross Sections of Welt Shoe and McKay Sewed Shoe     144

    Stitching                                            148

    Tacking                                              148

    Cross Section of Standard Screwed Shoe               160

    Side of Leather divided as to Quality                168

    Cross Section of McKay Sewed Shoe                    200

    Cross Section of Goodyear Welt Shoe                  200

    Crude Rubber                                         228

    Washing and Drying                                   232

    Calender Room                                        234

    Cutting Room                                         236

    Putting together the Parts of a Rubber Shoe          240

    Heel-making Department                               242

    Parts of a Rubber Boot                               248

    Insole for Hand-sewed Shoe                           264

    Hand-sewed Shoe                                      264

    Stitching Room of a German Shoe Factory              276




SHOEMAKING




CHAPTER ONE

FUNDAMENTAL SHOE TERMS


Before explaining the manufacture of shoes, it is necessary to fix
definitely in our minds the names of their different parts. Examine your
shoes and note the parts that are here described.

The bottom of the shoe is called the sole. The part above the sole is
called the upper. The top of the shoe is that part measured by the lacing
which covers the ankle and the instep. The vamp is that section which
covers the sides of the foot and the toes. The shank is that part of
the sole of the shoe between the heel and the ball. This name is often
applied to a piece of metal or other substance in that part of the sole,
intended to give support to the arch of the foot. The throat of the vamp
is that part which curves around the lower edge of the top, where the
lacing starts.

Backstay is a term used to denote a strip of leather covering and
strengthening the back seam of the shoe. Quarter is a term used mostly in
low shoes to denote the rear part of the upper when a full vamp is not
used. Button fly is the portion of the upper containing the buttonholes
of a button shoe. Tip is the toe piece of a shoe, stitched to the vamp
and outside of it. The lace stay is a term used to denote a strip of
leather reënforcing the eyelet holes. Tongue denotes a narrow strip of
leather used on all lace shoes to protect the instep from the lacing and
weather.

[Illustration: Names of the Different Parts of Foot Wear. _Page 2._]

Foxing is the name applied to leather of the upper that extends from the
sole to the laces in front, and to about the height of the counter in the
back, being the length of the upper. It may be in one or more pieces, and
is often cut down to the shank in circular form. If in two pieces, that
part covering the counter is called a heel fox. Overlay is a term applied
to leather attached to the upper part of the vamp of a slipper. The
breast of the heel is the inner part of the heel, that is, the section
nearest the shank.




CHAPTER TWO

HIDES AND THEIR TREATMENT


If we examine our shoes, we will find that the different parts are
composed of material called leather. The bottom of the shoe is of hard
leather, while the part above the sole is of a softer, more pliable
leather. This leather is nothing more than the hides of different animals
treated in such a way as to remove the fat and the hair.

After the hides have been taken from the dead body of the animal, they
are quite heavily salted to preserve them from spoiling. In this salted
condition they are shipped to the tanneries.

The process or series of processes by which the hides and skins of
animals are converted into leather is called tanning. The process may be
divided into three groups of subprocesses as follows:--

Beamhouse process, which removes the hair from the hides and prepares
them for the actual process of the tanning or conversion into leather;
tanning, which converts the raw hide into leather; and finishing, which
involves a number of operations, the objects of which are to give the
leather the color that may be desired and also to make it of uniform
thickness, and impart to it the softness and the finish that is required
for a particular purpose.

Hides are divided roughly in the tannery, according to the size, into
three general classes:--

(1) Hides, skins from fully grown animals, as cows, oxen, horses,
buffaloes, walrus, etc. These are thick, heavy leather, used for shoe
soles, large machinery belting, trunks, etc., where stiffness, strength,
and wearing qualities are desired. The untanned hides weigh from
twenty-five to sixty pounds.

(2) Kips, skins of the undersized animals of the above group, weighing
between fifteen and twenty-five pounds.

(3) Skins from small animals, such as calves, sheep, goats, dogs, etc.
This last group gives a light, but strong and pliable leather, which may
be used for a great many purposes, such as men’s shoes and the heavier
grades of women’s shoes.

The hides, kips, and skins are divided into various grades, according to
their weight, size, condition, and quality.

The quality of the hides not only depends upon the kind of animal, but
also upon its fodder and mode of living. The hides of wild cattle yield a
more compact and stronger leather than those of our domesticated beasts.
Among these latter the stall-fed have better hides than the meadow-fed,
or grazing cattle. The thickness of the hide varies considerably on
different animals and on the parts of the body, the thickest part of the
bull being near the head and the middle of the back, while at the belly
the hide is thinnest. These differences are less conspicuous in sheep,
goats, and calves. As regards sheep, it would appear that their skin is
generally thinnest where their wool is longest.

In the raw, untanned state, and with the hair still on, the hides are
termed “green” or “fresh.” Fresh, or green hides are supplied to the
tanners by the packers or the butchers, or are imported, either dry or
salted.

Hides are obtained either from the regular packing houses or from farmers
who kill their own stock, and do not skin the animal as scientifically as
the regular packing houses, in which case they are called country hides.
There are different grades of hides and leather, and these different
grades are divided in the commercial world into the five following
grades:--

I. NATIVE HIDES

    Native Steers
    Native Cows, heavy
    Native Cows, light
    Branded Cows
    Butts
    Colorado Steers
    Texas Steers, heavy
    Texas Steers, light
    Texas Steers, ex-light
    Native Bulls
    Branded Bulls

II. COUNTRY HIDES

    Ohio Buffs
    Ohio Ex.
    Southerns

III. DRY HIDES

(Raised on plain. Rough side suitable for soles.)

    Buenos Ayres

IV. CALFSKINS

(Green salted)

    Chicago City

V. PARIS CITY CALFSKINS

    Light
    Medium
    Heavy

Hides obtained from steers raised on Western farms are known as native
steer hides.

Native cowhide (heavy) is hide weighing from fifty-five to sixty-five
pounds, obtained from cows.

Native cowhide (light) is cowhide weighing under fifty-five pounds.

Branded cowhide is hide obtained from cows that are branded on the face
of the hide.

Butts is a term applied to the part of the hide remaining after cutting
off the head, shoulders, and strip of the belly.

Colorado steer hide is from Colorado steers, which are very light.

Texas steer hide comes in three grades, heavy, light, and extra light.
The heavy grade is very heavy because the animal is allowed to graze on
the plains. That is the reason why it is heavier than the Colorado steer
hide, which is raised on the farm.

Bull hide is divided into two classes, the regular hide and the branded
grade. The branded grade usually is one cent a pound less than the
regular.

Country hides are of three grades, Ohio Buffs, Ohio Ex., and Southern.
The Ohio Buffs weigh from forty to sixty pounds. The Ohio Ex. weighs from
twenty to forty pounds. Southern hides have spots without hair and other
blemishes on them, due to the sting of insects. This makes the Southern
hide inferior to the Ohio, Indiana, Michigan, and Chicago hides that have
no such blemishes. Ohio Butt hides are the best, because in Ohio they
kill a great many young calves, while in Chicago young cows (that have
calved) are killed, causing the hide to be flanky.

The season of the year in which cattle are slaughtered has considerable
influence upon both the weight and condition of the hide. During the
winter months, by reason of the hair being longer and thicker, the hide
is heavier, ranging from seventy-five to eighty pounds, and gradually
decreasing in weight as the season becomes warmer and the coat is shed,
until in June and July it weighs from seventy down to fifty-five pounds,
the hair then being thin and short. The best hides of the year are
October hides, and short-haired hides are better for leather purposes
than long-haired ones.

A thick hide which is to be used for upper leather is cut into sides
before the tanning process is completed. This is performed by passing
it between rollers where it comes in contact with a sharp knife-edge,
which splits it into two or more sheets. Great care must be exercised in
cutting the leather in order to have good “splits” (sheets of leather). A
split from a heavy hide is not as good as a whole of a lighter leather.

Butts and backs are selected from the stoutest and heaviest oxhides. The
butt is formed by cutting off the head, the shoulder, and the strip of
the belly. The butt or back of oxhide forms the stoutest and heaviest
leather, such as is used for soles of boots, harness, etc.

[Illustration: Green-Salted Calfskin. _Page 12._]

Hides and skins are received at the tannery in one of three conditions,
viz. green-salted, dry, or dry-salted. Very few hides are received by
tanners in fresh or unsalted condition, salt being necessary to preserve
them from decay. Green-salted hides are those that have been salted in
fresh condition, tied up in bundles, and shipped to the tanner. Dry
hides are those that were taken from the carcass and dried without being
salted; these are usually stiff and hard. Dry-salted hides are hides that
were heavily salted while they were fresh, and then dried. The hides
and skins that are received from the slaughterhouses of this country
are almost invariably green-salted; those from foreign countries are
green-salted, dry, and dry-salted.

It does not matter in what condition the hides are received or the kind
of leather into which they are to be tanned; they all require soaking in
water before any attempt is made to remove the hair or to tan them. The
object of the soaking process, as it is called, is to thoroughly soften
the hides and to remove from them all salt, dirt, blood, etc. Ordinary
hides are usually soaked from twenty-four to forty-eight hours. Dry hides
require much longer. The water should be changed once or twice during the
process, since dirty water may injure the hides. Soft water is better
than hard for this process. Where the water is hard, it is customary for
the tanner to add a quantity of borax to it to increase its cleansing
power and to hasten the softening of the hides.

When dry hides have become soft enough to bend without cracking, they are
put into a machine and beaten and rolled, then soaked again until they
are soft and pliable. It is very important that all the salt and dirt are
removed during the process of soaking, as they injure the quality of the
leather if they are not removed before the hides are unhaired. When the
soaking process is completed, the lumps of fat and flesh that may have
been left on by the butcher are removed by hand or by a machine, and the
hides are then in condition to be passed along into the next process. The
parts that cannot be made into leather, such as tails, teats, etc., are
trimmed off before the hides are soaked. Large hides are cut into two
pieces or halves, called “sides,” after they have been soaked.

For the purpose of taking the hair from the hides and skins, lime,
sulphide of sodium, and red arsenic are used. Lime is sometimes used
alone, but usually one of the other two chemicals is mixed with it. The
lime is dissolved in hot water, a quantity of either sulphide of sodium
or red arsenic is added to it, and the solution is then mixed with water
in a vat, the hides being immersed in this liquor until the hair can be
easily removed. The action of the unhairing liquor is to swell the hides,
then to dissolve the perishable animal portion and loosen the hair so
that it can be rubbed or pulled off.

There are several different processes of unhairing the hides. Each tanner
uses the process that will help to give the leather the qualities that it
should have, such as softness and pliability for shoe and glove leather,
or firmness and solidity for sole and belting leather. This is one of the
most important in the series of tannery processes, and if the hides are
not unhaired properly and not prepared for tanning as they should be, the
leather will not be right when it is tanned and finished.

There is also a process of unhairing, called “sweating,” which softens
the hide and loosens the hair so that it can be scraped off. In this
process the hides begin to decay before the hair is loose; it is
therefore a dangerous process to use and must be carefully watched or the
hides will be entirely spoiled. Sweating is never used for the finer,
softer kinds of leather. It is applied chiefly to dry hides for sole,
lace, and belt leather. It is an old-fashioned process and is not used as
much nowadays as some years ago.

The pelts of sheep are salted at the slaughterhouses and then shipped to
the tannery. Here they are thrown into water and left to soak twenty-four
hours to loosen the dirt and dissolve the salt. The pelts are next
passed through machines that clean the wool, and any particles of flesh
remaining on the inner or flesh side are removed. The pelts are then in
condition to have the wool removed. As long as a sheepskin has the wool
upon it, it is called a pelt; as soon as the wool has been taken off, it
is called a skin or a “slat.”

Each pelt is spread out smoothly on a table with the wool down and the
inner or flesh side up. A mixture of lime and sulphide of sodium is
next applied uniformly over the skin with a brush. The pelt is then
folded up and placed in a pile with others. The solution that was
applied penetrates the skin and loosens the wool, which, at the end
of twenty-four hours, more or less, can be easily pulled off with the
hands or rubbed off with a dull instrument or stick. The workman must be
careful not to get any of the solution on to the wool, as it dissolves it
and makes it worthless. Since the wool is valuable, the solution must be
applied to the flesh side very carefully so that it does no injury. The
wool that is removed from the skins is called “pulled wool.”

The slat is now ready to be limed, washed, pickled, and tanned. Heavy
skins are often split into two sheets after they have been limed. The
part from the wool side is called a skiver, and that from the flesh side
is called a flesher.

After the skins have been limed, they are bated and washed, which makes
them soft, clean, and white; they are then put into a solution of salt,
sulphuric acid, and water, called “pickle,” and after a few hours they
are taken out, drained, and tanned.

Large quantities of sheepskins are sold to tanners in the pickled
condition by those who make a business of preparing such skins and
selling the wool. Pickled skins can be kept an indefinite length of time
without spoiling; they can also be dried and worked out into a cheap
white leather without any further tanning whatever. Most of such skins,
however, are sold to tanners, who tan them into leather. Sheepskins
contain considerable grease, which must be removed before the leather can
be sold.

For some processes of tanning, calfskins, goatskins, and cattle hides are
also pickled the same as sheepskins; for other processes they are not
pickled, but are thoroughly bated or delimed, washed, and cleansed. Heavy
hides are sometimes split out of the lime; more frequently, however, they
are not split until after they have been tanned.

To capitulate, the preparatory processes may be briefly described as
follows:--

Soaking, which dissolves the salt, removes the dirt and makes the hides
soft and comparatively clean.

Liming and unhairing, which swell the hides and dissolve the perishable
animal portion, loosen the hair, and put the hides into proper condition
for tanning. Hides tanned without liming, even if the hair is removed by
some chemical, do not make pliable leather, but are stiff and hard.

Bating, which removes the lime from the hides.

Pickling, which helps in the tanning later, and keeps the hides and
skins from spoiling if they are not tanned at once.

The lumps of fat and flesh that may be on the hides are removed by
machinery or by placing the hide over a beam and scraping it with a
knife. The hair, when it is loosened by the lime, is removed by a machine
or by hand.




CHAPTER THREE

PROCESSES OF TANNING


The various processes of tanning may be roughly divided into two
classes, vegetable chemical and mineral chemical. The first class is
often spoken of in tanneries simply as the “vegetable” while the second
is called “chemical” process. In the vegetable processes the tanning
is accomplished by tannin, which is found in various barks and woods
of trees and leaves of plants. In the so-called chemical processes the
tanning is done with mineral salts and acids which produce an entirely
different kind of leather from that procured by vegetable tanning.

There is also a method of tanning, or, more properly speaking, tawing, in
which alum and salt are used. This process makes white leather that is
used for many purposes; it is also colored and used in the manufacture
of fine gloves. Leather is also made by tanning skins with oil. Chamois
skins are made in this way.

The materials that are used to tan hides and skins act upon the hide
fibers in such a way that the hides are rendered proof against decay
and become pliable and strong. There are many vegetable tans; they are
used for sole leather, upper leather, and colored leather for numerous
purposes. The bark of hemlock trees is one of the principal tans. The
woods and barks of oak, chestnut, and quebracho trees are often used.
Palmetto roots yield a good tan. Large quantities of leather are treated
with gambier and various other tanning materials that come from foreign
countries. Sumac leaves, which are imported from Sicily, contain tannin
that makes soft leather suitable for hat sweatbands, suspender trimmings,
etc. Sumac is also obtained from the State of Virginia, but the foreign
leaves contain more tannin and make better leather than the American.

To a large extent the so-called chemical processes have supplanted the
vegetable processes, that is, old tan bark and sumac processes; but in
some tanneries both methods are used on different kinds of skins.

In the old bark process the tan bark is ground coarse and is then treated
in leaches with hot water until the tanning quality is drawn out. The
liquor so obtained is used at various strengths as needed.

In the newer method the tan liquor is displaced by a solution of
potassium bichromate, which produces its results with much less
expenditure of time.

When the hides or skins are ready for the tanning process, they are put
into a revolving drum, known as a “pinwheel,” or into a pit in which
are revolving paddles, with a dilute solution of potassium dichromate
or sodium dichromate, acidified with hydrochloric or sulphuric acid.
If the pinwheel is employed, it is revolved for seven hours or longer;
after which time the liquor is drawn off and replaced by an acidified
solution of sodium thiosulphate or bisulphite, and then the revolution
is continued several hours longer. If the pit is used, the skins are
removed to another drum containing the second solution, and kept at rest
or overturned for a like period.

In removing the skins from the pinwheel or vat, and in handling them
after treatment with lime for the loosening of the hair, the hands and
arms of the workmen are seriously injured, becoming raw if not protected
by rubber gloves; even with gloves it is difficult to prevent injury, and
in some establishments the workmen are relieved by the substitution of a
single-bath process, in which the liquor is less harmful to the skin.

[Illustration: Tanning Process

Showing the vats, the unhairing and liming processes. _Page 24._]

The hides are then removed from the pits, washed and brushed, followed
by slow drying in the air. When partly dried, they are placed in a pile
and covered until heating is induced. They are then dampened and rolled
with brass rollers to give the leather solidity. Sole leather is oiled
but little. Weight is increased by adding glucose and salt.

Various rapid processes of tanning have been devised in which the hides
are suspended in strong liquors or are tanned in large revolving drums.
It is claimed that this hastens the process, but the product has been
criticized as lacking substance or being brittle.

Chrome tannage has been chiefly developed in this country during the
last twenty years and is now in general use. It consists in throwing an
insoluble chromium hydroxide or oxide on the fibers of a skin which has
been impregnated with a soluble chromium salt--potassium bichromate.
Other salts like basic chromium chloride, chromium chromate, and chromic
alum are also used. The hydrochloric or sulphuric acid acts by setting
free chromic acid.

After several hours, the skin shows a uniform yellow when cut through its
thickest part. It is then drained and the skin worked in a solution of
sodium bisulphite and mineral acid (to free sulphur dioxide). The chromic
acid is absorbed by the fiber and later reduced by sulphur dioxide.

In the making of chrome black leather each tanner has his own method.
Contrary to the general belief, there are many different methods of
chrome tannage. No two tanneries employ just the same process.

Tanners of chrome leather seek to produce leather suitable for the
particular demands made upon it by the peculiarities or characteristics
of the varying seasons. Summer shoes require a cool, light leather;
at other times a heavier tannage is essential, with some call for a
practically waterproof product.

All leathers, whether vegetable-or chrome-tanned, must be “fat liquored.”
That is to say, a certain amount of fatty material must be put into the
skin in order that it may be mellow, workable, and serviceable. This is
very essential in producing calf leather. Fat liquors usually contain oil
and soap, which have been boiled in water and made into a thin liquor.
The leather is put into a drum with the hot fat liquor; the drum is set
in motion, and as it revolves the leather tumbles about in the drum and
absorbs the oil and soap from the water. It is the fat liquor that makes
the leather soft and strong.

Leather used in shoes is divided into two classes: sole leather and upper
leather.

Sole leather is a heavy, solid, stiff leather and may be bent without
cracking. It is the foundation of the shoe, and therefore should be of
the best material. The hides of bulls and oxen yield the best leather for
this purpose.

The hide that is tanned for sole leather is soaked for several days in a
weak solution (which is gradually made stronger) of oak or hemlock tan
made from the bark. Oak-tanned hide is preferred and may be known by its
light color. A chemical change takes place in the fiber of the hide. This
is a high-grade tannage, and is distinguished principally by its fine
fibers and close, compact texture.

Oak sole leather, by reason of its tough character, and its close,
fibrous texture, resists water and will wear well down before cracking.
It is by many considered better than other leather for flexible-sole
shoes, requiring waterproof qualities.

Sole leather is divided into three classes according to the tanning--oak,
hemlock, and union.

[Illustration: Tanning Process

Showing the rotating drums. _See page 24._]

Oak tanning is as follows: the hides are hung in pits containing weak
or nearly spent liquors from a previous tanning, and agitated so as to
take up tannin evenly. Strong liquor would harden the surface so as to
prevent thorough penetration into the interior of the hides. After ten
or twelve days, the hides are taken out and laid away in fresh tan and
stronger liquor. This process is repeated as often as necessary for eight
to ten months. At the end of this time the hide has absorbed all of the
tannin which it will take up.

Hemlock tanning is similar to the oak tanning in process. The hemlock
tan is a red shade. Hemlock produces a very hard and inflexible leather.
It is modified by use of bleaching materials which are applied to the
leather after being tanned. It is sold in sides without being trimmed,
while the oak is sold in backs, with belly and head trimmed off.

Hemlock leather is used extensively and almost principally for men’s
and boys’ stiff-soled, heavy shoes, where no flexibility is required
or expected. Its principal desirable quality is its resistance to
trituration, or being ground to a powder, and its use in men’s and boys’
pegged, nailed, or standard screw shoes is not in any way objectionable
to the wearer. In fact, for this class of shoes, it is probably the best
leather that can be used. But when hemlock is used in men’s and boys’
Goodyear welt shoes, where a flexible bottom is expected and required,
it generally does not give good results. It cannot satisfactorily resist
the constant flexing to which it is subjected, and after the sole is worn
half through, the constant bending causes it to crack crosswise. On this
account it becomes like a sieve, and has no power of resistance in water,
and therefore it is not at all suited to flexible-bottomed shoes.

In “union-tanned” hides, both oak and hemlock are used and the result is
a compromise in both color and quality. This tan was first used about
fifty years ago. Twenty-five years ago the union leather tanners began to
experiment with bleaching materials to avoid the use of oak bark, which
was becoming scarce and high priced, and eventually developed a system of
tanning union leather with hemlock or kindred tanning agents, excluding
oak. The red color and the hard texture were modified by bleaching the
leather to the desired color and texture. This produces leather which
has not the fine, close tannage of genuine oak leather and at the same
time lacks the compact, hard character of hemlock leather. Union leather
produced in this manner is a sort of mongrel or hybrid leather, being
neither oak nor hemlock. On account of its economy in cutting qualities,
however, it is largely used in the manufacture of medium-priced shoes
where a certain degree of flexibility is required in the sole. This is
particularly true of women’s shoes.

Union leather is sold largely in backs and trimmed the same as oak,
though not so closely.

Sole leather is also made nowadays by tanning the hides by the chrome or
chemical process. This leather is very durable and pliable and is used
on athletic and sporting shoes. It has a light green color and is much
lighter in weight than the oak or hemlock leather.

Many kinds of hide are used for sole leather. This country does not
produce nearly enough hides for the demand, and great quantities are
imported from abroad, although most of the imported hides come from South
America. Imported hides are divided into two general classes, dry hides
and green-salted hides.

Dry hides are of two kinds, the dry “flint,” which are dried carefully
after being taken from the animal and cured without salt. These generally
make good leather, although if sunburnt, the leather is not strong.
“Dry-salted hides” are salted and cured to a dry state. Dry hides of both
