Page:Encyclopædia Britannica, Ninth Edition, v. 14.djvu/405

 LEATHER 387 purpose, the skin is boarded, or worked with a grainin^ board or pommel C (fig, 10), the effect of which is to bring up the grain, or give a granular appearance to the leather^ and also to make it supple. The pommel is a piece of hard wood, grooved like a crimping-board, and attached to the hand by means of a strap, whence the word pommel, from the French paumelle, or palm of the hand. The leather passes through various manipulations, each having its distinct name ; thus graining consists in folding the skin with the grain sides in contact, and rubbing strongly on the flesh side ; bruising, or rubbing the extended skin on the grain side; whitening, or passing a knife with a very fine edge over the skin at the beam, so as to clean the flesh side preparatory to waxing, which is done just before the skins are sold ; for at this point the currier stores his skins, as they can be kept best in the state of finished russet, as it is called, previous to waxing. Waxing consists of two parts: the first is the laying on the colour, or black ing of oil, lampblack, and tallow, which is well rubbed in on the flesh side with a hard brush ; then, secondly, the skin is black-sized with stiff size and tallow, laid on with a sponge or a soft brush, and thoroughly rubbed with a glass slicker, a finishing gloss being given with a little thin size. The curried skin is now said to be black on the flesh, or waxed, in which state it is used for the upper leathers of men s boots and shoes. In the case of any of the numerous varieties of grained leather which are blackened and dressed on the grain side, the finishing operations are different. These are hard dried after slicking, and the operation of stuffing or dubbing is omitted. They are grained in the dry state, often by machinery, then boarded to soften them, and next blackened on the grain side with a solution of copperas. The flesh side is whitened ovflvffed and the grain is treated with sweet oil or some similar oil, and finally glazed with a thin solution of gelatin or of shellac. For almost ever} operation in currying efficient machinery has now been adapted, the use of which not only modifies the operations of the currier, but also enables him to split up hides and to linish his splits as imitations of any kind of leather he may desire to copy. In machine currying the tanned hides, duly damped, are struck out in a &quot;stoning &quot; machine. It consists of a strong oscillating arm or bar having a blunt steel blade fixed on its end, which works back and forward over a concave bed on which the hide is laid, and which by its scraping and striking action on the softened leather .smooths and equalizes the grain, and produr.es a compact uniform surface on FIG. 11. Belt Knife Splitting Machine. it. From the stoning machine the hide may pass to the splitting machine, of which the.re are numerous forms, the American union splitter with a fixed knife being the oldest and best known. A much more perfect machine, however, is the belt or band splitting machine. In this machine (fig. 11) the knife or cutter a is an end less band of steel which revolves at considerable speed with its cutting edges close to the sides of a pair of rollers through which the leather is fed and pressed against the knife. The lower of these rollers is made of short segments or rings, each separately capable of yielding to some extent so as to accommodate itself to the inequal thicknesses of various parts of a hide. The thickness of the slice ot leather to be cut is gauged to the utmost mmuJeness by means the hand screws b, b, which raise or lower the upper roller. The kuiie edge of the cutter is kept keen by rubbing against revolving emery wheels c as it passes round. So delicately can this machine eilect its work that slices of leather uniform throughout and as thin as paper can be easily prepared by it, and with its help it is no uncommon practice to divide a comparatively thin East Indian kip into three useful splits. Another machine now largely used by curriers is the scouring machine (fig. 12), a level table or platform treely movable in all directions, having mounted over it a recipro cating frame m which are fixed brushes and pieces of slate or thin FIG. 12. Scouring Machine. stone. These, with a small jet of water, scour and brush the entire surface of the leather lying on the platform, effectually scouring out bloom and all soluble impurities. Other machines are washing and stuffing drums and whitening machines. In the latter the leather is pared and equalized by the cutting action of a small cylinder armed with oblique cutting edges. The cylinder, moved to and fro with a pendulum motion, and revolving at the enormous rate of from 2000 to 3000 revolutions per minute, pares and shaves the leather on the same principle as the lawn-mower cuts grass. Embossing or graining cylinders, boarding cylinders, glassing machines, and emery wheels for fluffing the flesh side of levant leather are also among the mechanical adaptations for currier s use. Patent or Enamelled Leather. Leather finished with a brilliant, smooth, and glossy surface, used for dress boots and shoes, dress belts, and fine harness, is known under a variety of names, as lacquered, varnished, japanned, and enamelled leather, &c. Such leather is finished principally from tanned calf skins, and in more recent times from seal, goat, and sheep skins, but lighter ox hides and horse leather are also japanned for special purposes. The finishing of leather in this style involves two processes (1) the grounding or preparation of a smooth surface, and (2) the varnishing and polishing. The grounding material used by French and German finishers, who greatly excel in the production of such leather, consists of a thick syrupy mixture of lamp-black with a varnish of boiled linseed oil, umber, and litharge. This is uniformly spread over the surface of the leather, which has been previously stretched and tacked on a wooden frame. The first coating is dried in the air, then exposed in the japanning stove to a heat of about 170 Fahr., and afterwards rubbed smooth with pumice stone. This process of coating, drying, and smoothing is repeated several times, and the leather is next varnished with a compound of boiled oil, Berlin blue, litharge, and some dryer, thinned either with oil of turpentine or petroleum spirit. Two or three thin coat ings of such varnish are given, the surface being carefully polished after each ; but the composition of the varnishes, &c., and the number of coatings applied, vary much in the hands of different manufacturers. Coloured enamel leathers receive two preliminary coatings of oil, rosin, and spirit of turpentine, which are sun-dried ; they are then brought up