Transcriber's note:
Spelling and punctuation inconsistencies been harmonized.
Obvious printer errors have been repaired. Italic text has been
marked with _underscores_. Bold text has been marked with
=equal signs=. Subscript numbers have been rendered, as for
example for subscript 2, as _{2}.
LEATHER
_Common Commodities and Industries Series_
Each book in crown 8vo, cloth, with many illustrations, charts, etc.
=2s. 6d.= net.
=Tea: From Grower to Consumer.= By A. Ibbetson.
=Coffee: From Grower to Consumer.= By B. B. Keable.
=Sugar: Cane and Beet.= By Geo. Martineau, C.B.
=Cotton: From the Raw Material to the Finished Product.= By R.
J. Peake.
=Rubber: Production and Utilisation of the Raw Product.= By C.
Beadle and H. P. Stevens, M.A., Ph.D., F.I.C.
=Iron and Steel: Their Production and Manufacture.= By C. Hood.
=Silk: Its Production and Manufacture.= By Luther Hooper.
=Tobacco: From Grower to Smoker.= By A. E. Tanner.
=Wool: From the Raw Material to the Finished Product.= By J. A.
Hunter.
=Coal: Its Origin, Method of Working, and Preparation for the
Market.= By Francis H. Wilson, M. Inst. M.E.
=Linen: From the Field to the Finished Product.= By Alfred S.
Moore.
=Timber: From the Forest to its Use in Commerce.= By William
Bullock.
=Clays and Clay Products.= By A. B. Searle.
=Leather: From the Raw Material to the Finished Product.= By K.
J. Adcock.
=Oils: Animal, Vegetable, Essential, and Mineral.= By C.
Ainsworth Mitchell, B.A., F.I.C.
=Wheat and its Products.= By A. Millar.
=Copper: From the Ore to the Metal.= By H. K. Picard, Assoc.
Royal School of Mines, Mem. Inst. of Min. and Met.
=Paper: Its History, Sources, and Production.= By H. A. Maddox.
=Glass and Glass Manufacture.= By Percival Marson.
=Soap: Its Composition, Manufacture, and Properties.= By
William H. Simmons.
=The Motor Industry.= By Horace Wyatt, B.A.
=The Boot and Shoe Industry.= By J. S. Harding.
=Gums and Resins.= By Ernest J. Parry.
=Furniture.= By H. E. Binstead.
_Other Volumes in preparation._
[Illustration: BLEACHING OIL-TANNED LEATHER BY EXPOSURE TO THE SUN
The Rosary Leather Mills. Ashtead]
_PITMAN'S COMMON COMMODITIES
AND INDUSTRIES_
LEATHER
FROM THE RAW MATERIAL TO THE
FINISHED PRODUCT
BY
K. J. ADCOCK
LONDON
SIR ISAAC PITMAN & SONS, LTD., 1 AMEN CORNER, E.C.4
BATH, MELBOURNE AND NEW YORK
PRINTED BY SIR ISAAC PITMAN
& SONS, LTD., LONDON, BATH,
MELBOURNE AND NEW YORK
CONTENTS
CHAP. PAGE
I. EVOLUTION OF LEATHER MANUFACTURE 1
II. HIDES AND SKINS 5
III. TANNING MATERIALS 32
IV. MACHINERY 52
V. PREPARATION OF HIDES AND SKINS FOR
TANNING 62
VI. TANNING PROCESSES 91
VII. DRESSING, DYEING, AND FINISHING OF
LEATHER 112
INDEX 159
LIST OF ILLUSTRATIONS
PAGE
BLEACHING OIL-TANNED LEATHER _Frontispiece_
MECHANICAL FLAYING 23
PIM'S SYSTEM OF FLAYING 24
WARBLE FLY 28
WARBLED KIP (584 HOLES) 29
WARBLED HIDE (MAGNIFIED) 30
TANNING EXTRACT PLANT 48
SHAVING CYLINDER 53
BLADED CYLINDER FOR BUFFING 54
BAND-KNIFE SPLITTING MACHINE 54
SHAVING KNIFE 55
SHAVING MACHINE _bet. pp._ 56 & 57
SHAVING, OLD METHOD 56
SHAVING MACHINE, KNIFE GUARD 59
SHAVING MACHINE 61
DRUM TUMBLER 67
FALLER STOCKS 67
TANNER'S BEAM 68
LIME YARD 73
DEHAIRING KNIFE 80
DEHAIRING AND FLESHING MACHINE 81
FLESHING KNIFE 83
SCUDDING KNIFE 86
BARK MILL 93
TAN-YARD 94
ROUNDING OF HIDES 95
BARKOMETER 97
PADDLE VAT 103
PINNING SOLE BUTTS 121
ROLLING MACHINE 122
ROLLING SOLE LEATHER 123
FAN FOR DRYING 124
FAN FIXED IN CHAMBER 125
SUTCLIFFE SYSTEM OF DRYING 126
SLEEKER 128
FLUFFING MACHINE 129
STRIKING-OUT AND SCOURING MACHINE 130
LEATHER-STUFFING DRUM 135
STAKING AND GLAZING MACHINE 143
LEATHER
CHAPTER I
EVOLUTION OF THE ART OF LEATHER MANUFACTURE
Before describing the making of leather by up-to-date methods, it may
be useful to attempt to outline the evolution of the ancient art of
tanning and dyeing skins. As everyone knows, leather is the preserved
skin of various animals, but the origin of the conversion of raw
skins into an imputrescible material will probably never be traced,
and it can only be assumed that the processes necessary to produce
leather from skins were gradually and, in most cases, accidentally
discovered. Long before the Christian era, the ancient Egyptians
had succeeded in bringing the manufacture of leather to remarkable
perfection, and, had they at their service the wonderful machinery
now available to the leather industry, it is certain that their
productions would have lost little or nothing by comparison with
modern leather. Happily, specimens of ancient Egyptian leather have
been preserved in one national museum, and, although they are said
to have been made at least 3,000 years ago, the colour and natural
strength of the leather are unimpaired.
Judging by the advanced state of the art of leather manufacture in
the early Egyptian period, it is obvious that the origin of its
manufacture must have considerably antedated that period, and,
indeed, it would be necessary to go back almost to the creation of
man to find the origin of the use of preserved animal skins for
clothing. The primitive method would naturally consist of simply
drying the skin, in which condition it would keep for many years
unless it came into contact with moisture, though its horniness
would no doubt cause the wearer much discomfort. It must not be
supposed that the wearing of dried raw skins with the hair left on
was impracticable, for even to-day some of the skins of fur-bearing
animals used for personal adornment are cured in this primitive
way, with the additional treatment with napthalene for disinfecting
purposes and keeping away injurious insects and moths, the object of
the limited amount of dressing being to preserve the natural strength
and coloration of the fur. In such a condition, however, the skins
are liable to acquire an unpleasant odour, and for hygienic reasons
it is advisable that all skins in the hair used for clothing or rugs
should be properly dressed, so that no decay sets in to loosen the
hair or fur.
Even now, the process of simply drying hides and skins to preserve
them before sending them to the tanner is largely practised,
especially in hot climates and in those countries where salt is not
readily available. This process of curing rests on the chemical
theory of dehydration, which, in a modified form, has recently been
successfully applied to some experiments in making leather.
Finding that the simple drying of skins would not properly prepare
them for clothing, primeval man would naturally look for some means
of treating them to conserve their original softness and pliability,
and the nearest substances at hand would be animal fats and brains.
It is almost safe to assume that this process was the first by
which hides were preserved in a state differing from their original
condition, the oxidation of the fatty matters naturally producing a
partial tannage. The effect of smoke may also have been discovered in
the earliest days of skin-curing, and it is reported that even now
one or two tribes use smoke to preserve skins.
The somewhat imperfect preservation of the hides by this method would
lead to further experiments being made, which evidently resulted in
the discovery of the tanning effect of leaves, twigs, and barks of
trees when soaked in water. It may be that the preservative effect
of alum was discovered even before the vegetable tanning process,
for the original Japanese white leather was made simply by steeping
the raw hides in certain rivers which contained a bed-rock of alum.
This primitive process is even followed to-day in one or two places
in Japan, but the leather is afterwards treated with oil to impart
tensile strength and increased suppleness. Strictly speaking, these
hides are not leather when finished, and they are quite unsuitable
for boots; but, being the toughest material known in the leather
trade, with the possible exception of raw hide, it is particularly
suitable and chiefly used for brace ends, and occasionally for
ladies' belts. It must not be inferred from reference to this process
that the Japanese only use this earliest method of making leather;
on the contrary, they are producing all classes of leather, and
especially belting and sole, by modern European methods, and it may
not be long before their competition with American and European
productions becomes an accomplished fact.
The available information seems to show that, until about thirty
years ago, the development of the industry was mainly the result
of accidental discoveries, and that the theory of tanning and
leather-dressing was imperfectly understood until within quite recent
times. Records of the leather trade 300 years ago prove that the
methods then in vogue were of the rudest kind; further, they show
that the practice of skimping the tanning process was not unknown
in those days, for a contemporaneous author describes the horny
condition of some of the leather which, despite the Government
inspection, appeared to have passed into the old Leadenhall
market for sale by the simple operation of "greasing the fist of
the seller." Spain and Hungary had by that time established the
manufacture of morocco and curried leather on a fairly sound basis,
while a few years later France began to develop the industry of
leather manufacture. Until about twenty years ago, waxed calf,
crup, calf kid, and alum-tanned kid were staple upper leathers,
together with the old Spanish cordovan leather. The sole leather
used in England was chiefly the output of tanneries in the United
Kingdom. About twenty years ago, however, the successful application
of the chrome tanning process caused quite a revolution in the
leather trade, with the result that about nine-tenths of the world's
production of boot upper leather is chrome-tanned. The introduction
of this process on a practical scale gave a great impetus to the work
of chemists, who have since made some remarkable discoveries and have
placed the art of leather manufacture on a scientific basis.
The old methods, however, are by no means obsolete, and it is
somewhat remarkable to find that a British patent was taken out last
year (1914) for converting hides and skins into leather by treating
them with brains and smoke.