388 LEATHER
with several coatings of oil, varnish, and the special colouring substance, and finished with a thin coat of copal varnish.
Seal Leather. – The tanning of seal skins is now an important department of the leather industry of the United Kingdom, in which this branch has been specially developed. The skins form one of the items of the whaling industry, which principally centres in Dundee, and at that port, as well as at Hull and Peterhead, they are received in large quantities from the arctic regions. A considerable number are also imported at Greenock from the coast of Newfoundland. The skin of these seals is light but exceedingly close in texture, and yields a very strong tough leather. The skins are prepared, split, and tanned in the same way as other light leathers, tanning with mixed oak bark and sumach usually occupying about six weeks. Seal leather is generally finished on the grain side as "levant" seal with a large coarse grain, and in that form it is principally used by bootmakers. A proportion of seal leather is finished as enamel and japanned leather.
Russia Leather was originally, as the name implies, a speciality of Russia, where it was made from the hides of young cattle, and dressed either a brownish-red or a black colour, for upper leather or for bookbinding, dressing cases, purses, and similar objects. Russia leather is now made throughout both Europe and America, the best qualities being obtained from Austria. Horse hides, calf, goat, and sheep skins, and even splits, are now finished as russia leather; but most of these are decidedly inferior in quality, and, as they are merely treated with birch bark oil to give them something of the odour by which an ordinary observer recognizes russia leather, they scarcely deserve the name under which they pass. Genuine russia leather is tanned like other light leathers, but properly in willow bark, although poplar and spruce fir barks also are used. After tanning, scouring, and setting out, the hides are treated on the flesh side with an empyreumatic oil obtained by the dry distillation of birch tree bark and buds, to which the peculiar smell of the leather is due. The red colour commonly seen in russia leather is given by dyeing wkh a preparation of brazil wood, rubbed over the grain side with a brush or sponge. Black-coloured russia leather owes its colour to repeated stainings with acetate of iron. The leather of genuine quality is very water-tight and strong, and, owing to its impregnation with empyreumatic oil, it wards off the attacks of insects.
Morocco and Thin Leathers. – Originally morocco leather was a product of the Levant, Turkey, and the Mediterranean coast of Africa, where the leather was made from goat skins tanned with sumach, and finished either black or various bright colours. Such leather was peculiarly clear in colour, elastic, and soft, yet firm and fine in grain and texture, and has long been much prized for bindings, being the material in which most of the artistic work of the 16th century binders was executed. Now, in addition to genuine morocco made from goat skins, we have imitation or French moroccos, for which split calf and especially sheep skins are employed, and it may be said that, as the appearance of morocco is the result of the style of graining, which can be artificially produced on any leather, and of the finish, morocco can be made from all varieties of thin leather. The Germans distinguish between saffian and morocco, including under the former term leather tanned with sumach, and dyed bright colours without previous stuffing with fats, while as morocco proper they reckon leather which may be prepared with mixed tannage, is stuffed, and afterwards is finished black. Saffians are, according to this classification, the leathers principally used for bindings and fancy purposes, morocco being more especially devoted to shoe work.
The preparation of skins for morocco leathers must be conducted with much care. The skins, being usually hard and dry when received, are first soaked and softened by milling in the stocks and working on the tanner's beam. They are next limed, unhaired, fleshed, and trimmed in effect as already described in the section on sole leather, and they are pured or bated in a preparation of dog's dung. After undergoing the influence of this preparation, the skins are washed and slated with a knife-edged piece of slate to remove from their surface fine hairs and adhering dirt, and then they are put into a drench of bran and water, heated to about 185° Fahr., after which they ought to be perfectly free from deleterious impurities and ready for tanning. Several processes are adopted in tanning, but that most approved is based on the original Eastern practice, which consists in first treating the skins with an already used sumach infusion. Next they are, in pairs, sewed up as bags, grain side outwards, and these bags are filled with concentrated sumach liquor and a proportion of powdered sumach, and by the exudation of the liquor through the skins, partly aided by pressure, the tanning is quickly completed. After ripping out, the skins are thrown into vats containing sumach liquor, to tan the edges and shanks, which are not reached by the liquor in the bags. The fully tanned skins are now struck out on the beam with the striking pin, and hung in the loft to dry, when they are ready for the finishing processes. A large proportion of the goat skins imported into western Europe from the East Indies, whence they are exported in enormous quantities, are received in the fully tanned condition, and ready for the morocco finishing operations, after a short treatment with sumach liquor. For finishing, the leather is first damped in soap-suds, and shaved on the flesh side to equalize the thickness of the leather, and next on a table worked over repeatedly with slickers, which renders the skin firm, smooth, and uniform. The skins are next blacked on the grain side with a solution of acetate of iron, and from this point the methods of finish diverge in an endless manner according as it is desired to finish the leather as "kid," "levant," "peebled," "bright," or "dull," &c. The bright-coloured moroccos are dyed in two different methods, the dyeing being done as a preliminary to the finishing operations. In the case of genuine moroccos, the skins are dipped and drawn through small troughs containing the dye liquor; two skins are taken, placed flesh side to flesh side, and so worked through the liquor by hand, the operation being repeated as often as necessary to bring up the requisite strength of colour. Imitation morocco, on the other hand, is usually dyed by stretching the skins on a table and brushing the dye liquor over the grain side. After the dyeing the skins are shaved and dressed, the dyed surface is rubbed over with an emulsion of white of egg, linseed oil, and dye liquor, and afterwards grained and glassed, or finished smooth and glossy, according to the purpose for which the leather may be required. In recent times aniline colours have been very largely employed in the dyeing of all bright leathers.
In the tanning of sheep and lamb skins the general operations outlined above in the case of goat skins are necessary. Previous to tanning, the prepared skins are submitted to hydraulic pressure, to expel the oleaginous matter with which sheep skins are richly impregnated. Sheep skins tanned, generally with beech bark in the United Kingdom, and uncoloured are known as basils. Roan Leather is sheep skin tanned in sumach, coloured and dressed throughout in the same manner as imitation morocco, excepting that it is finished smooth and glassed. Skivers are split grain sides of sheep skins tanned in sumach, and similarly finished, the flesh split being shamoyed for inferior qualities of shamoy or wash leather. Skivers from their thinness are quickly tanned through in a sumach
