Leather and Textile Uses of Fats and Oils

Abstract

Although most of the 20-odd steps of leathermaking use fats and oils as detergents, by far the majority of these materials are used as additives to soften leather. Oils are usually applied in aqueous emulsions while the leather is still wet from tanning. Several oils are conventionally used, often made self-emulsifying by partial sulfation or sulfonation by treating with sulfuric acid. These oils are called fatliquors. Aside from softening, a smaller amount of oils and fats as detergents are also used in preliminary cleaning of the raw skins and hides; to suspend lime particles, buffer the alkaline solution that removes the epidermis and hair, and suspend these materials when they come off; to remove grease; to tan certain types of leather; and to control the penetration of dyes. The discussion shows the importance of oils and fats in the processing of textiles. As a result of oxidative stability, synthetic oils have superseded their natural counterparts. However, fatty acids from natural oils still play an important role in the processing of textiles. There is considerable pressure on the textile industry to reduce the amounts of these additives, or to eliminate them completely, because of the environmental implications of the effluents. In response to this, considerable effort is being made in the industry to develop additive-free processes. Keywords: textile processing; leathermaking; fatliquors; leather softening; synthetic oils; spinning; scouring; dyeing