What the deuce is leather currying? Luke Herbert explains in this excerpt from The Engineer’s & Mechanic’s Encyclopaedia, published in 1849:
This operation, which usually forms quite a distinct business, consists in a peculiar mode of dressing or preparing leather for boots, shoes, harness, and a variety of other things. The dressing of a calf skin for the upper-leathers of shoes, will give a general idea of the process. The offal parts, such as the head, tail, and shanks, being first taken off, (which is called rounding the skin,) it is soaked in a tub of waterpreparatory to shaving, which is performed upon a beam. The beam is a post fixed in an inclinedposition, and faced with lignum-vitse, about 8 inches broad. The knife is a stout rectangular blade, about 12 inches long and 5 inches wide, with two edges; one end has a straight handle, and the other a cross handle in the direction of the plane of the blade. A coarse and a fine grit whet-stone are used to bring up the edge of the knife, which is afterwards turned to a “wire edge” by means of a steel instrument, which the workman constantly holds between his fingers. The mode of using the knife has already been noticed.
In order to keep the substance of the skin equal, the man frequently examines it in the course of shaving in every part, by passing it double between his fingers; and when sufficiently reduced, he throws it a second time into a tub of cold water to be scoured and extended; for this purpose it is laid upon a stone table, to which the flesh side adheres, and is there worked with the edge of a small square stone fixed in a handle: pumice stone is sometimes used. With a brush the skin is cleansed from a substance called the bloom, which all leather, tanned with bark, is found to contain. After being thoroughly cleansed and distended while in its wet state, it is stuffed with a mixture of two parts cod oil, and one part tallow, called dubbing, which is applied to both sides of the skin, but chiefly on the flesh side. It is then hung up to dry, by which the moisture evaporates; and the oil, which cannot be dissipated by mere exposure, gradually takes the place of the moisture, and sinks deeply into the pores of the skin.
The leather is next boarded or bruised, by a grooved piece of wood (like a crimping board) that is fastened to the hand by a strap; with this the skin is doubled and worked until made very flexible; it is next “whitened,” that is, lightly shaved over again, by which the flesh side is well cleaned, and it is brought into a proper state to receive the colour used in waxing. Before it is waxed, however, it is boarded a second time, when it is in that state called finished russet, in which state it can be best preserved; therefore, until it is wanted for 6ale, the subsequent operations called waxing are left undone. The “colour,” or blacking, is a composition of oil, lamp black, and tallow, which is well rubbed into the flesh side with a hard brush, great care being taken to keep the flesh side clean. A coat of strong sizeand tallow is then laid on with a soft brush; it is afterwards rubbed with a smoothing glass; and lastly, it receives the finishing gloss from a little thin size laid on with a sponge. After the first coat of size the skin is laid up to dry and incorporate, and a lump of hard tallow is rubbed lightly over the surface; the skin is thus completely finished for the consumer; and leather so dressed is found superior in point of appearance and durability to any other method.
The curriers also blacken leather on the grain side, which is done by rubbing it with a solution ofcopperas, which, combining with the gallic acid of the tan, produces a black.
Russia Leather is prepared in Russia by a series of processes not essentially differing from our own. The tanning material is, however, seldom oak bark, the bark of the black willow being preferred; and where this cannot he obtained, birch bark is the next in request. Their dyed leather is usually red or black. For the red, the hide is first soaked in alum water, and then dyed with Brazilwood. The black is given, as usual, with an iron liquor. The leather is then smeared with birch tar, which gives the peculiar smell so much prized (and which, when used for book-binding, has the valuable property of protecting the book from worms), and is finished by various other manipulations. The streaked or barred surface is given to the leather by a very heavy steel cylinder, wound round with wire, which makes the indentations.
Saffian or Dyed Maroquin Leather, of excellent quality, is extensively prepared at Astracan and other parts of Asiatic Russia. Only bucks’ and goats’ skins are used for this purpose, and the favourite colours are red and yellow. The general method of preparing the pelt is the same as in this country for the dyed Morocco leather; that is, by lime, dog’s dung, and bran. Honey is also used after the branning. The honey is dissolved in warm water; and some of this liquor is poured out on each skin, spread out on wooden trays till it has imbibed the whole of the honey; after which it is suffered to ferment about three days, then salted in a strong brine and hung up to dry. The skin is then ready to receive the dye, which, for red, is made with cochineal, and the Salsola ericoides, an alkaline plant, growing plentifully in the Tartarian salt deserts, and the colour is finished with alum. When dyed the skins are tanned withsumach. To the very finest reds a quantity of sorrel is used with the cochineal bath; and the subsequent tanning is given with galls instead of sumach, which renders the colour as durable as the leather itself. The roughness always observed on the surface of the skins, is given by a heavy kind of iron rake with blunt points.
The yellow saffians are dyed with the berries of a species of shamnus (the Avignon berry answers the same purpose), or with the flowers of the wild chamomile.
Real Morocco Leather, as prepared from goat skins at Fez and Tetuan, is thus described by M. Bruffonet in the Bulletin des Sciences. The skins are first cleansed, the hair taken off, limed, and reduced with bran, nearly in the same way already described for the English Morocco leather. After coming from the bran they are thrown into a second bath, made of white figs mixed with water, which is thereby rendered slimy and fermentable. In this bath the skins remain four or five days, when they are thoroughly salted with rock salt alone (and not with salt and alum), after which they are fit to receive the dye, which, for the red, is cochineal and alum; and for the yellow, pomegranate bark and alum. The skins are then tanned, dressed, supplied with a little oil, and dried.