GB180758A - Improvements in or relating to the tanning of skins and hides - Google Patents

Abstract

180,758. Hell, J. March 1, 1921. Mineral tanning; tanning with aldehydes, sulphite liquors, and other special chemicals; combination tanning processes; currying, impregnating, and the like.-Hides and skins are tanned by means of soluble magnesium salts and soluble carbonic-acid salts of other bases in the presence of water. A mixture of the dry salts may be introduced into a drum containing the wet hides, the moisture being sufficient to dissolve, the salts and render them active, or the hides or skins may be drummed successively in separate solutions of the salts. The process may be applied to partially-tanned hides, or may be combined with other processes such as tanning or treatment by cellulose sulphite liquors, formaldehyde, chrome, iron, or other mineral tanning-agents, or vegetable tanning-agents, used in admixture or separately. In an example, 100 kg. of unhaired hides are drummed for four to six hours or longer in a concentrated solution containing 21 to 22 kg. of magnesium sulphate and 7 kg. of sodium bicarbonate or 9 kg. of sodium carbonate, or the hides mav be first drummed in a solution of one of the salts, the other salt being added subsequently. This treatment may be followed by rinsing and oiling or by treatment with fat, grease &c. to which formaldehyde has been added, or the hides may be pressed out or exposed to the air, then coated or brushed over with cellulose sulphite liquor and afterwards rolled and greased. Alternatively, the cellulose extract may be added to the tanning mixture. Formaldehyde, chrome, alum or salts of iron, zinc or barium or small quantities of vegetable tanning materials such as oak extract may be added to the tanning mixture described in the example, or may be employed in separate solutions for subsequent treatment. In a further example the hides, after treatment with the mixed salts and formaldehyde, are steeped in milk of lime and then further treated as in the first example. The various processes are stated to produce heat-resisting qualities, durable graining or embossing &c., firm or soft texture &c. as required. Specification 2873/98 is referred to.