Vegetable and aluminium combination tannage: aboon alternative to chromium in the leather industry

Abstract

Severe restrictions imposed by the pollution control authorities on chromium have forced tanners to look for possible alternatives that are naturally abundant, easily obtainable, low priced, eco-friendly and offer competitive tanned leather performances. In this study, the interactions of vegetable and aluminum, with collagens, have been investigated. This type of combination process helps to improve the shrinkage temperature, percentage of elongation at break, tensile strength, tear strength at 125 o C, 65.5%, 38 N/mm 2 , and 98 N/mm, respectively. The combination offers full, soft leathers which have a shrinkage temperature comparable to conventional chrome tanned skins. Among the combination systems evaluated, a vegetable pretannage followed by aluminum retannage was better than the aluminum pre-tanning followed by vegetable retannage. Optimal results were obtained when 10% vegetable tannins and 2% aluminum sulphate were used.