Fig. 60.
The dry leather is rapidly passed through tepid water, and after being hung for a very short time, to allow the water to drain off, is trodden tightly into chests, and allowed to remain in them for about 12 hours, so that the moisture may be uniformly distributed. It is then trodden on hurdles (Horden), composed of square bars of wood, joined corner to corner, so as to make a floor of sharply angular ridges, [Fig. 59]. The next operation is stretching over a circular knife, called the Stollmond (stollen, Eng. "staking"), shown in [Fig. 60]; then the leather is dried nearly completely, and staked again.
Dyeing.
The dyeing of glove-kids is done in 2 ways:—a. The skins are plunged into the dye-bath (Tunkfarben). In this way, all light colours are ordinarily produced, such as gris-perle (pearl-grey), paillé (straw-yellow), chamois (reddish yellow), silver-grey, aquamarine, &c. b. The skins are spread on an inclined or rounded table of stone or metal, and brushed over, on the grain side, first with a mordant (Beize), then with the dye-liquor, and lastly, with a solution of a mineral salt ([Plate 7]). The mordant serves to fix the colour on the surface of the skin, to prevent its striking through, to produce certain modifications of colour, and to enable any parts of the skin which yet contain fat to take the colour evenly with the rest. To satisfy these conditions, the composition of the mordants is very varied. Potash bichromate, ammonia, potash, soda, and stale urine are among the most frequently employed, seldom separately, but usually in a mixture containing 2 or more.
Dye-stuffs of vegetable origin have always held the first place. Those most in use are logwood (Blauholz), Brazilwood (Rothholz), the two fustics—Cuba Gelbholz (Morus tinctoria) and Ungarisches Gelbholz (Rhus cotinus), several species of willow-bark and of berries, indigo-carmine, and indigo dissolved in sulphuric acid.
Aniline colours used alone remained in fashion for a short time only, but are now usefully employed as top-colours (Ueberfarben), viz. brushed in very dilute solution over vegetable colours. In this way, particularly tasteful shades of green, violet, and marine-blue may be produced.
After the mordant has been applied once or twice, and the colour 3-6 times, a wash (Ueberstrich) containing some metallic salt is generally applied, with the object either of bringing out the special tone required, or of making the colour more lively and permanent. The so-called "vitriols" are mostly employed: "white vitriol" (zinc sulphate), "blue vitriol" (copper sulphate), "green vitriol" (iron sulphate), and occasionally other salts.
Before dyeing, the greater part of the flour, salt, and alum must be removed from the skins by washing with tepid water; and they therefore require a second feeding (Nahrung) of egg-yolk and salt. In the case of the skins which are dyed by plunging into the dye-vat (Tunkfarben), this is done after the dyeing is completed; in that of brush-dyeing, before the dyeing process.
After the dyeing, the skins, if dipped, are wrung out; if brush-dyed, sleeked out with a brass plate, to get rid of superfluous water. They are then dried in an airy room. Before staking (stretching), the skins are laid or hung in a damp cellar, or in moist saw-dust. They are staked twice: once damp, and once nearly dry.