Abstract

As an alternative to chrome tanning, and after having carried out a study of the availability at a local and regional level, chemically unmodified pine bark could be used as a natural source of tannins in order to obtain a vegetable-tanned leather. The aim of this work was to design a pre-tanning formulation using pine bark powder. To increase the penetration of vegetable tannins and use short floats in vegetable tanning, while reducing overall tanning times, three types of synthetic agents were studied: a phenolic syntan, a disulphonic agent and a naphthalene sulphonic syntan. Once, having selected the most appropriate syntan, an experimental design was developed in order to obtain an optimised formulation based on pine bark powder and syntan. The optimal pre-tanning formulation uses a 15% offer of pine bark powder and 2.5% of naphthalene sulphonic agent.