The Principles of Leather Manufacture

The products which are of no direct value to the tanner and currier in the manufacture of leather, and which are nevertheless obtained in fairly large quantities, are of very va...

As has been stated in the previous chapter, our knowledge of the chemistry of tannins is not sufficiently advanced to render possible any strictly chemical classification, while...

Although lime is in many respects the most useful and satisfactory means of loosening hair from hides and skins, it is of the greatest importance that it should be completely re...

After the softening and cleansing of the hide or skin is completed, and before proceeding to tan it, it is usually necessary to remove the hair or wool. The earliest method of a...

Fats and oils constitute a large class of substances, of animal or vegetable origin, which may be solid, pasty or more or less viscous liquids, but which in the latter case are...

Before the discovery of artificial organic dyestuffs, the only colouring materials known to industry were those of mineral and direct organic origin; and on this account the dye...

Questions of evaporation, whether for raising steam, or for the concentration of tanning extracts and other solutions are of considerable importance in the tanning industry, and...

_Iron tannages_ may be very shortly dismissed, as their practical interest is at present either historical or prospective, but iron salts enter in so many ways into the chemistr...

The nature of the changes which take place in the conversion of raw hide into leather, and the causes of swelling and “falling” in the various stages of the wet-work and tannage...

_Leaching._--The material, having been reduced to a suitable state of fineness, is ready for extraction. This requires a considerable amount of time, as the tannin is contained...

available to the tanner, but these are always costly and troublesome, and the possibility of running direct into a sewerage system, or a tidal river is of great advantage. Under...

The chemistry of the various constituents of skin is still very imperfectly understood, but Beilstein, in his great handbook of organic chemistry, places gelatin, albumens and k...

The processes employed in the production of leather with the vegetable tanning materials vary extremely according to the class of leather which is being produced, both in the ma...

Although the analysis of tanning materials falls more properly within the scope of a book for chemists than one intended primarily for tanners, and though it has been treated at...

The conversion of skin into leather by the agency of oils and fats is probably one of the most primitive methods, and is used in different ways suited to the skins and fats whic...

Of all the materials employed in tanning, none is of more indispensable importance than water, and its quality has undoubtedly great influence on tanning, though it is constantl...

A considerable proportion of the hides and skins used in leather manufacture are those of animals killed by the butcher for food, and these are frequently employed by the tanner...

“Antiseptics” are often defined as substances which check putrefaction without necessarily destroying bacteria and their spores, while “disinfectants” are poisonous to ferment-o...

the pelt, becoming converted into a basic salt (see p. 187). The acid not only swells the pelt, and renders it incapable of producing a soft leather, but the swollen pelt is les...

As has been explained in the last chapter, hides and skins come into the hands of the tanner either uncured (“green”), as they are taken off the animal, preserved with salt or s...

Before the tannin they contain can be extracted, most materials require to be ground, almost the only exceptions to this rule being divi-divi and algarobilla, in which the tanni...

Although, at first sight, the skins of different animals appear to have little in common, a closer examination shows that all the Mammalia possess skins which have the same gene...

In very early times leathers were produced, which were partly tanned with alum, and partly with vegetable materials. One of the earliest of these was probably the Swedish or Dan...

The chemical changes produced by the unicellular plants, such as yeasts and bacteria, to which allusion has been made in the last chapter, are known as fermentation and putrefac...

The essential constituents of tanning materials are members of a large group of organic compounds known as “tannins” or “tannic acids,” which are widely distributed throughout t...

The origin of leather manufacture dates far back in the prehistoric ages, and was probably one of the earliest arts practised by mankind. The relics which have come down to us f...

The larger part of the materials employed in leather manufacture are organic in their origin, and the skin itself is an organised structure, while the life-processes of putrefac...

We have now followed the raw material up to the final stage of preparation for its actual conversion into leather, and it remains to consider the means by which that important c...

The object of tanning has been stated to be the rendering of animal skin imputrescible and pliable, but as we now rarely require leather with the hair on, preliminary processes...

Hair -- Fleshings and glue-stuff -- Fat -- Bate-shavings -- Horns -- Spent tan -- Tan-furnaces -- Sewage and other waste liquids -- Chemical purification of sewage -- Settling t...

Characteristics of fats and oils -- Chemical constitution -- Nature and production of soaps -- Insoluble soaps -- Distillation of fats -- Solvents of oils -- Drying oils -- Satu...

Methods of removing lime and reducing swelling -- Use of acids -- Lactic, acetic and formic acids -- Boral -- Sodium bisulphate -- Boric (boracic) acid -- Borax -- “Pulling down...

As few architects have specially studied the construction of tanneries, and in most cases much of the arrangement depends on the knowledge of the tanner himself, a short chapter...

Methods of depilation -- Sweating process -- Liming -- Sources of lime -- Quicklime -- Slaking of lime -- Solubility of lime in water -- Analysis of lime -- “Available” lime --...

Causes of swelling and contraction -- The essentials of the tanning process -- The constitution of matter -- The nature of molecules -- Vapour-pressure -- Surface-tension -- Sol...

Leaching -- Early forms of leaches -- The press-leach system -- Handling of liquors -- Distributing troughs and valves -- Construction of leaches -- Influence of temperature --...

Theory of evaporation -- Boiling point and vapour-pressure -- Consumption of heat in evaporation -- Heat-units -- Mechanical energy of heat -- Evaporation by “multiple effect” -...

Iron tannages -- Chrome tannages -- Chemistry of chromium compounds -- Knapp’s method of chrome tannage -- Cavallin -- Swan -- Heinzerling -- Hummel’s improvement -- Schultz’s m...

Distinction of antiseptics and disinfectants -- Lime -- Sulphur dioxide -- Manufacture of sulphuric acid -- Bisulphites and metabisulphites -- Boric acid and borates -- Mercuric...

The nature of ferments -- Organised and unorganised ferments -- Classification of organised ferments -- General properties of ferments -- The alcoholic fermentation -- The actio...

Impurities of natural water -- Hardness -- Soap test -- Temporary hardness -- Clark’s softening process -- Archbutt and Deeley’s softening apparatus -- Other appliances -- Effec...

Coal-tar colours -- Acid and basic colours -- Theories of dyeing -- Fixation of colours on leather -- Mordants and mordant colours -- Curriers’ inks -- Glazes and finishes -- “A...

The International Association of Leather Trades Chemists -- The American Official Association of Agricultural Chemists -- The sampling of material -- Preparation of solution for...

Primitive use of oil in leather manufacture -- Chamoising and the production of washleather -- Manufacture of Moellon, or Dégras -- Sod oil -- Formaldehyde leathers -- “Crown” a...

Primitive methods of grinding -- The bell mill or coffee mill -- Disc mills -- Disintegrators -- Carr’s disintegrator -- Carter’s disintegrator -- Adjustment of disintegrators -...

Similarity of Mammalian skins -- Development of skin -- Structure of calf-skin -- The epidermis -- The structure of hair -- The sebaceous glands -- The development of hair -- Th...

Selection of site -- Arrangement of buildings -- Fire insurance -- Automatic sprinklers -- Possibility of extension -- Production and distribution of power -- Electric motors --...

The keratin tissues -- Production of gelatine from connective tissue -- Analyses of hide and gelatine -- Constitution of gelatine -- Analysis and Reactions of gelatine -- Decomp...

Marking of hides -- Fellmongering of sheep-skins -- The use of salt -- Salting of packer hides -- Brining -- Dry-salting -- Indian plaster cures -- Analysis of salt-earths -- Sa...

Methods of sole-leather tanning -- Finishing of sole-leather -- Theory of vegetable tannage -- Deliming of sole-leather -- “Mellowness” of liquors -- Penetration of tannage -- D...

Primitive methods of leather manufacture -- Use of leather by the ancients -- Progress of leather manufacture in England -- Methods of production of leather -- Vegetable tannage...

Early combination tannages -- Respective effect of mineral and vegetable tannages -- Use of fat-liquor -- Action of mineral and vegetable tanning materials on each other -- Dani...

Washing of fresh hides -- Danger of putrefaction -- Soaking of salted hides and skins -- Soaking and softening of dry and dry-salted hides -- American wash-wheel -- Chemical met...

The object of tanning -- Washing and soaking -- Removal of hair by liming -- Unhairing by putrefaction -- Unhairing and fleshing -- Deliming -- Bating, puering and drenching --...

Nature of leather -- Mineral tanning substances -- Salts of aluminium -- Alums -- Aluminium sulphate -- Effect of salt in tawing -- Basic alumina solutions -- Tawing of skins fo...

Sources of tannins -- General qualities of tannins -- Chemical constitution -- Catechol- and pyrogallol tannins -- Catechins -- Tendency of Catechol tannins to darken with light...