This section is from the book "The Manufacture Of Boots And Shoes: Being A Modern Treatise Of All The Processes Of Making And Manufacturing Footgear", by F. Y. Golding. Also available from Amazon: The Manufacture Of Boots And Shoes.
For best bespoke, high prices are obtained, and quality is a great consideration. Economic cutting would therefore be a secondary consideration, fitness and suitability for the purpose intended being the primary object to be attained. The parts would be matched from opposite places, either side of the backbone. When bespoke is produced in a factory, or where economy is a consideration, order or stock work would be cut, and the special run in.
Calf or Wax Calf Skins are first tanned with bark, afterwards being curried or stuffed with oleaginous substances. These skins excel in strength and flexibility, notwithstanding their comparative thinness. They are curried and blackened on the flesh side of the skin. The French-dressed calf is considered the best, being mellow, more durable, conforming to the last easier, and is of a better appearance than English skins. The English skins are darker on the grain, harsher in hand, and are "kippy " in appearance. They should be well rounded and the offal well got out. There should be a freedom from growth marks and the shoulders free from veins. The neck should be short and level in substance, and the skin feel plump and firm. The shanks, etc., should be short, and free from ragged ends. The edge of the butt should be as straight as possible. The backbone should not fall away suddenly. The skin should feel firm and mellow, and when folded between thumb and finger should not be flabby nor "tinny," and not exude grease. There should be a freedom from flesh cuts that are oftentimes hidden on the black face.
The female skins are considered best for superior work, the texture being finer. In cutting, the hip bone and backbone should be usually avoided, except for inferior purposes. The necks are oftentimes reversed, and make serviceable material when blackened. Several grades of qualities may be produced, and good judgment is needed in the cutting and costing.
Memel calf is dressed on the grain, and is not much used.
Russet calf is imported both for lining and currying purposes. Bordeaux calf is considered the finest sort.
Satin calf is buffed, hence its smooth appearance.
The American calf at first sight appears finer, but it is not a reliable article, either for appearance or wear.
Chrome calf, under various trade names, is largely coming into general use, and is usually a good wearing and good looking article.
In brown calf-skins the so-called growth marks are conspicuous, and care should be taken in placing the patterns so that they may be arranged where the least strain is likely to be experienced, owing to the tendency of their opening and cracking when subjected to strain. The shades of colour should be mated or matched.
Willow calf is boarded and finished on the grain.
Calf Kid is tawed and not tanned. The dried or salted selected calf-skins are softened in water, after which cleaning they are limed until the hair is loose. They are un-haired and fleshed, and pured with dung. Next, they are scudded and cleansed in bran drench. The tawing is accomplished in drums, with a mixture of alum and salt. After drying, the skins are moistened and a mixture of oil, flour, and egg-yolks worked into them. In Germany these operations are combined. The skins are drained, and after damping, are staked, i.e. drawn over posts, working with a blunt knife. They are again wetted and shaved, and sometimes, to soften them, are dressed with oil, flour, and egg-yolk. They are dyed black, and after grounding are rubbed on the grain with a fatty composition, being finally ironed to give them a fine, smooth surface.
The cutting of calf kid requires good judgment, the work when cut feeling different in substance than when in the skin. Firm, large kids are adaptable for systematic cutting, but the lighter, softer kinds have to be carefully watched for the correct disposition of the relative tighter material. The number of qualities producible, and the importance of keeping them well paired up, make this leather a very fluctuating one for commercial purposes. The three kinds usually met with are English, French, and German.
The English kid is firm and fine on the grain. It does not readily break up or pipe, if of good dressing. The fibres on the flesh side appear short and closer than the German. They are not so soft or supple as the French, especially near the grain. They take the edge readily from the knife when being skived, and do not therefore make an ideal leather for "turning in "or" beading." The varieties have both white and blue backs.
The French kids are of the small kind, and are therefore finer than the English. The fibres are dense and compact. The leather is soft, and suitable for " turning in' or "beaded" work, where suppleness or softness is required. The grain readily breaks up, or pipes, and hence does not make a suitable selection for factory produce, owing to the handling necessary for the processes, and the consequent poor appearance when completed. They are not so nice in appearance for such purposes as those of German or English makes.
The German kids are larger skins, and as a consequence are coarser in grain. The fibres are of such a nature that they skive easily, having a flannelly or loose appearance on the back. They are usually white-backed. Some of the makes are equal to the English. The smaller sized skins in some makes are similar to the French skins. The German skins are considered cheap cutting, but owing to the introduction of chrome calf they are not being dressed in sufficient quantities to supply adequately the demand.
Calf Patent is well stretched before enamelling or japanning, and is japanned on the flesh side. The japanning is done by coating the stretched skins with a paint of linseed, lampblack, and Prussian blue. Several coats are applied, and finally they are varnished. The skins are dried in a stove at a temperature from 160° to 170° F.
Patent should be free from flaws, and have little offal. It should also be firm in texture, not flabby, and the japan should be elastic without any tendency to brittleness.
It should be cut from the brown or grain side, the japan coming next to the board. This will ensure clean-cut edges. Vamps may be "turned in " or folded, if skived on Amazeen, and folded on the Luf kin, having a better appearance than if left raw edge. The toe of the vamp when cut from patent should be solid, but not brittle. Vamps may be cut up to the neck, or across the butt, according to the class of work and quality of patent, when a couple of rows may be taken each side of the backbone. Caps are best cut if worked to a system, a straight line being drawn to regulate same at the butt. If the cap be peaked, the second row may be so cut that the point left in first row may be utilized. Straight caps cut to advantage also when the patterns are systematically placed.
Patent tipping is japanned or enamelled on the grain side, and varies considerably in quality. It is made from split hides.
Horse Hides are dressed as cordovan, a leather that is durable, fine in texture, and susceptible of taking a high polish. It should not be lasted so tightly as calf. Crup butts, cordovan-cross-pieces, etc., are made from portions of horse hides. Crup, when properly tanned, is waterproof, and easy to wear; but if badly tanned, burns and blisters the feet of the wearer. Horse hides are split, and enamelled, and marketed as enamelled horse. The bellies are stuffed and sold as grain or smooth. Horse hide is also used for "flat calf " and horse kid.
Goat Skins vary considerably in size, thickness, and quality. They are finer in texture, and tougher than sheep skins. They are variously dressed. Moroccos - oily and shumac tanned - are made from goats. Persian goats, memel goat, levant goat, and Strasbourg, are varieties of leather made from goat skin.
They are chromed as glace chromes, and if carefully selected are a very durable leather. An outline of the chroming by the two-bath process is as follows :The skins having been brought into a suitable condition for tanning, are first treated in a solution of bichromate of potash, to which has been added sufficient acid to liberate a part of the chromic acid. In this solution they remain until the fibre is thoroughly struck through. They are then drained, or pressed, and passed into a second bath consisting of thio-sulphate of soda, to which acid is added to liberate sulphurous acid. In this manner the chromic acid and bichromate in the fibres are reduced to a green chromium salt, which fixes itself in the fibres, rendering it quite insoluble, even in boiling water - in fact, converting it into a perfect kind of leather.
Sheep Skins when tanned with bark are known as "bazils." Sometimes they are split, the upper, or grain, side being tanned with sumach, and called "skivers." Roans are made from sheep skins. Imitation moroccos are made by tanning with sumach. The value of a sheep skin for leather purposes is in inverse proportion to its value for wool. Sheep skins are tawed, and known as alum mock kids. When tanned and stuffed, they are called mock kids. Persian sheep skins are considered the best. Sheep skins have not much wearing capacity, and are not favoured for the covers or outsides of boots or shoes.