Russia Leather (Gan., Juchtenleder). —This is tanned in Russia with the bark of various species of willow, poplar and larch, either by laying away in pits, or handling in liquors, much like other light leathers, the lime being first removed by bating, either in a drench of rye- and oat-meal and salt, by dog-dung, or by sour liquors. After tanning, the hides are again softened and cleansed by a weak drench of rye- and oat-meal. They are then shaved down, carefully sleeked and scoured out, and dried. The peculiar odour is given by saturating them with birch-bark oil, which is rubbed into the flesh-side with cloths. This oil is produced by dry distillation of the bark and twigs of the birch (see Oils—Birch-bark). The red colour is given by dyeing with Brazil-wood ; and the diamond-shaped marking by rolling with grooved rollers.
Much of the leather now sold as " Russia" is produced in Germany, France, and England. It is tanned in the customary way, occasionally with willow-, but more generally with oak-bark, and probably other materials. Economy would suggest the use of such materials as, from their red colour, are objectionable for other purposes, and therefore cheap. The currying is in the usual manner, care being taken that the oil used does not strike through to the grain, which would prevent it taking the dye. The colour is given by grounding with a solution of chloride of tin (100 parts perchloride tin, 30 parts nitric acid, 25 parts hydrochloric acid, allowed to stand some days, and the clear solution poured off, and mixed with 12 volumes of water). The dye-liquor may be com posed of 70 parts rasped Brazil-wood, 3 parts tartar, and 420 water, boiled together, strained, and allowed to settle clear. The grounding and dyeing is done on a table with a brush or sponge (see Glove-kid dyeing, p. 1239). The odour is communicated by rubbing the flesh-side with a mixturo of fish-oil and birch-bark oil, which sometimes contains no more than 5 per cent. of the latter.
Calf-kid.—Calf-kid is used for light upper-leather, and belongs to a different class from any yet described, being" tawed" instead of tanned. In this respect, and in most details of its manu facture, it resembles glove-kid.
The process is as follows. Selected calf-skins, dried or salted, are the raw material, and after a suitable softening in fresh water, are limed for 2-3 weeks, or till the hair goes easily. They are then unhaired and fleshed in the usual manner, pured with a bate of dogs' dung, scudded, and again cleansed with a bran drench. In Germany, the bran drench is used alone, and is composed of 33 lb. bran to 100 medium skins. Before use, the bran should, especially in summer, be well washed to free it from adhering meal. The temperature of the drench should not exceed 38° (100° F.), an .l the skins should remain in for 8-10 hours. Lactic acid is produced by fermentation ; this removes lime, and is itself neutralized by the products of putrid fermentation which succeeds it.
The tanning is accomplished in a drum with a mixture of alum and salt ; and after drying, the skins are again moistened, and worked in the drum with a mixture of oil, flour, and egg-yolk. In the German method, these two operations are combined. Eitner, who has written a series of articles on the process, gives 40 lb. flour, 20 lb. alum, 9 lb. salt, 250 eggs, or about 1-k gal. of egg-yolk, pint a litre) of olive-oil, and 12-16 gal. water, as a suitable mixture. The skins are worked in a drum-tumbler (preferably a square one) for 20 minutes, then allowed to rest ten minutes, and this process is twice repeated. The temperature must not exceed 38° (100° F.), and it is said to be important that the drum should be ventilated by holes at the axis.
The skins are allowed to drain, arethen rapidly dried at a temperature of 60°-71° (14F-160° F.), and, after " aamming," or damping with cold water, are staked by drawing them to and fro over a blunt knife fixed on the top of a post. They are then wetted down and shaved, either with the moon-knife or ordinary colliers' shaving-knife, and sometimes receive a second dressing of oil, flour, and egg, to soften them still further.
Dyeing black is accomplished either by brushing on a table, or by "ridging" or folding, grain side outwards, and drawing quickly through baths of the mordant and colour. To prepare them for the colour, stale urine is generally employed. A deeper colour, and ooe less liable to strike through the skin, is obtained by adding lb. bichromate of potash to 4 gal. of urine, or the follow ing mixture may be substituted with advantage, viz. s lb. Marseilles soap dissolved in boiling water, 5 or 6 egg-yolks added, and the whole made up to 4 gal. with water and lb. biehromate of potash. The colour used is infusion of logwood or its extract, or two-thirds logwood, which is best extracted by stale urine or old soak-liquor, with addition of a small quantity of soda (1 lb. to 25 lb. dye-wood). It is fixed and darkened by a wash of iron-liquor (1 of protosulphate of iron in 75 of cold water). After being again dried, the skins are grounded with the moon-knife, and rubbed over on the grain with a composition containing oil, wax, 86c., and are finally ironed with a flat-iron, to give them a fine and smooth surface. Eitner gives a recipe for the gloss :-1 lb. gum arable, lb. yellow wax, E lb. beef-tallow, I lb. Marseilles soap, 2 lb. strong logwood infusion, and 1 gal. water. The water is brought to a Boil in an earthen pot, and then the soap, wax, gum, and tallow are added successively, each being stirred till dissolved before adding the next, and lastly the logwood. After boiling for an hour, it is allowed to completely cool, being incessantly stirred during the whole process.