Prevention of chromium(VI) formation by improving the tannery processes

Abstract

This work has been funded by the European Commission through the Chrom6less Project (CRAFT -1999-71638). The objectives of the project were: - Establishment of the analytical methodology which provided reproducible results that may be free of interferences. - Identification of the factors that facilitated or impeded the transformation of Cr(III) to Cr(VI). - Establishment of the best conditions that allowed the production of chromium(VI) free leather, even during the life of the product, in contact with environmental agents such as light or heat. The following partners participated in the project: Inpelsa, Dercosa, Proquip, Igualada Leather Technology School, CID-CSIC and Miguel Hernandez University, from Spain, Gmelich, Knoll Sitzleder, and Lederinstitut Gerberschule Reutlingen from Germany, and Conceria Il Cigno, Calzaturificio Accademia and Stazione Experimentale from Italy. Hundreds of samples have been analysed during the project. In order to study the influence of several factors in chromium (VI) formation, a lot of skins/hides have been produced. Several leather articles (hides for clothing, footwear, upholstery, leather goods and furniture upholstery and skins for suede and double face)) have been manufactured free from Cr (VI). The main results obtained were: - The new analytical method CEN/TS 14495 has been validated. - Protective measures for the prevention of chromium (VI) formation have been identified. - New formulations for several hides/skins have been developed. - A handbook for the production of chromium (VI)-free leather has been published. The main conclusions of the project were: - The Chrom6less Project has shown that most of the skins/leathers did not contain hexavalent chromium. - It is now possible to confidently determine the Cr(VI) content in all kinds of leather regardless of their colour. - The application of protective measures developed in the Project allows leather to resist the effect of ageing without the formation of Cr(VI).