ABSTRACT
The use of leather goes back to prehistoric times when the principal raw material was hides or skins of mammals including, to a small extent, reptiles, fish and birds. A tanning operation consists of converting the raw skin, a highly putrescible material,
into leather, a stable and mechanically resistant matter, which can be used in the manufac ture of a wide range of products (shoes, clothing, bags, furniture and many other items of daily use). The whole operation involves a sequence of complex chemical processes and mechanical treatments, of which the fundamental stage is tanning. When coupled to preand posttreatments, this confers to the final product specific properties as stability, appear ance, water resistance, temperature resistance, elasticity, permeability to perspiration and air, etc. [1],
The valorization of hides and skins also generates by-products that find outlets in several industry sectors such as pet and animal food, fine chemicals including cosmetics, photogra phy intermediates, soil conditioners and fertilizers.
