Dyeing of Leather : Different colours may be imparted to leather, according to the uses for which it is designed. Thus, a blue is given by immersing the piece for the space of twenty-four hours in urine and indigo, after which it is boiled in alum ; or this colour may Le communicated by tempering the indigo with red wine, and steeping the skins in the mixture.
A red colour is obtained, by first washing the skins, which are then soaked for .the space of two hours in galls, wrung out, and immeresed in a liquor prepared by a solution of privet (Ligustrum vulgare, L.), alum, and verdigrease in water ; when they are steeped in a dye made of Brazil-wood boiled with ley.—In order to communicate a purple, the skins are wetted with a solution-of Roman alum in warm water; and when dry, they are rubbed by the hand with a decoction of logwood in cold water.
Leather acquires a light-green tinge, by applying to it sap-green diluted with boiled alum-wafer :—. a dark-green cast is communicated by means of steel-tilings and sal ammoniac, steeped in urine for a considerable time, and well rubbed into the skin, which is then to be dried in the shade.
A yellow colour is given, by anointing the skin with a decocition of aloes and linseed-oil, previously strained; or, by immersing it in a solution of dyer's-green weed. Lastly, if fustic-berries be boiled in alum-water, and the skins dipped in the liquor, they will acquire a light-orange shade; but, if a deeper hue be required, it will be necessary to substitute turmeric for the berries.—For an account of the preparation of red, yellow, or other Turkey Leather, we refer the reader to the article Morocco.
Leather being an article of extensive utility, especially for shoes and boots, various processes have been contrived for rendering it water-proof': we have already stated a simple method to this effect (vol. i. article Boot) ; and that our readers may become fully-acquainted with this interesting branch of economy, we shall now give a - supplementary account, of the different preparations, etc.invented for that purpose.
In the 2d vol. of Medical Inquiries and Observations (8vo. Philadelphia, 1793), Dr. Rush states the following mixture to be eminently calculated for rendering shoes, etc. impermeable to water. One pound of linseed-oil, eight ounces of mutton suet, six ounces of bees-wax, and four 6unces of resin, are to be melted together ; and, while moderately-warm, to be applied both to the upper leather, and the soles of boots.—Dr. Rush remarks, that this cheap recipe was taken from. The Complete Fisherman, a work published during the reign of Queen Elizabeth; and has, for many years, been employed with great success by the fishermen in America.
A patent was granted in 1794 to Mr. John Bellamy, for his new-invented method of making all kinds of leather water-proof.—For this purpose, the patentee has contrived two compositions, which are prepared in the following manner :
First method: One gallon of nut-oil, and an equal quantity of poppy-oil, are to be mixed with three gallons of linseed-oil; or, one gallon of nut, or poppy-oil, may be added to three of that expressed from linseed : or, two gallons of the latter may be combined with one pint of nut, and a similar quantity of poppy-oil. These ingredients (in the proportions above mentioned, or such as the nature of the oil may require) are to be poured together in an iron-pot, and placed over a gentle fire : to each gallon of oil must be allowed one pound of white copperas, sugar of lead, colcothar, or any other drying substance. The whole is to remain for the space of six or seven hours over such a degree of heat, as it will bear without rising, till it become sufficiently dry;
L£A when it may be taken off; and, as soon as it is cool, the compound will be fit for use.
Second method: Gum resin, one pound; pitch, half a pound; tar and turpentine, of each four ounces, are to be added to one gallon of the oils prepared according to the first method: these ingredients are to be we 1 mixed with the oils, first by gently heating the whole mass, then increasing the fire, till the whole become thoroughly incorporated.—The patentee specifies various proportions, in which the ingredients may be used ; but experience will be the best guide to ascertain them.
When the oils, prepared conformably to the first method, or the gums, etc. according to the second, are sufficiently cool, Mr. Bellamy directs a brush to be dipped in the preparation, which should be rubbed into the leather. As soon as that article is thoroughly impregnated, it ought to be laid on an even board, and the superfluous matter removed from its surface. With respect to sole leather, or similar thick substances, he observes, that they should first be gently warmed; the composition is then to be applied till they are fully saturated ; and, after being properly dried in a warm place, they will be ready for use.
In the Memoirs of the Academy of Sciences of Turin, for 1789, we meet with an interesting communication by M. de St. Real ; on the. means of rendering leather (especially that destined for soles) impermeable to water, without diminishing its strength.—This object, he conceives, may be effected, without any alteration in the usual method of tanning, by the common operations of currying; provided the skins be compressed in certain heavy rollers, after being previously immersed in beef-fat, or oil. The additional greasing, and pressing, will not greatly increase the price of sole-leather ; which, after being a whole year in tanning, imbibes water in a much smaller proportion than cow-leather, when dressed with fat.—We regret that our limits do not permit us to specify the very ingenious experiments made by M. de St. Real ; as we are convinced they will contribute to improve the art of tanning.
Another method of preventing leather from being penetrated by water, consists in exposing it with the flesh-side towards the fire : after winch, a coat of warmed tar is to be applied with a proper brush, three or four times successively, according to the thickness of the leather, till the liquid matter penetrate through the whole skin. The durability and strength of shoes, etc. will be considerably increased, if, in laying on the last coat of tar, they be sprinkled over with a small quantity of fine iron-filings, which will, in a manner, fill up the pores of the leather. Lastly, shoes may be rendered impermeable to moisture, by occasionally rubbing the soles with hot tar: thus the feet may be preserved dry and warm; an important object in this climate, especially during the winter season.
Various acts of parliament have been passed, relative to the dressing, bringing of leather to market, etc. for the greater convenience of trade, and to prevent fraudulent practices; but, as they relate wholly to curriers, tanners, and leather-cutters, we shall not enter into detail respe6ting them.- This article pays at present, on importation, the prohibitory duty of 841. 14s.
per cent, according to its value and is entitled only, to a drawback of 25 per cent, on being again ex-ported.