Improving the properties of wet-white tanned leather

Tanning is the main process for obtaining leather, which is satisfactorily durable and less susceptible to decomposition. Nowadays mineral tanning is of technical importance for leather manufacturing considering the properties and performance. Mineral tannage is the preference in many leather types so that leathers become softer, lighter and more flexible as well as having higher hydrothermal stability as compared to vegetable tannage. Also it is too appropriate for dying and fatliquoring processes and can be finished through different ways. Among the mineral tanning agents, chromium salts have a distinction and it is known as ideal tanning agents considering the characteristics. Although chromium salts are being mostly used due to their high hydrotermal stability and good organoleptical properties, their usage has been restricted because of advers effects on environment and human health. The risks deal with heavy metal accumulation and oxidation to toxic hexavalent form. Due to the risks, recently alternative tannages have been replaced with chromium in order to make use of the mineral tanning advantages lacking with other organic tanning procedures. In today's trends toward chrome-free tanning technology, zirconium, aluminium, titanium and organic phosphoniım salts are principal options alternatively to chromium tannage. Although leathers are mineral tanned having distinct properties such as better durability, superior performance and good dyeability, they are not chemically stable and satisfactorily soft and flexible as well as having appropriate hydrothermal stability. Thus the leathers, namely wet-white, need to be upgraded with some other tanning agents in order to eliminate some economical and technical drawbacks. In this thesis, it has been studied on the leathers having compatible properties to that of chromium by using zirconium, aliminium, phosphonium salts and their combinations along with natural polymers such as gelatine, whey protein. Also an alternative technology has been introduced to the industry for improving the wet-white characteristics using waste proteins such as gelatine by products, thereby helping promote the ecofriendly aspects in leather industry. Keywords: Leather, tanning, Wet-White leather, Chromium free leather.