Studies on waterproofing wet-white leather

Water resistance remains one of the more difficult goals to attain in leather manufacture. Although much is known from a scientific perspective, a problem persists when waterproofing wet-white leathers. The aim of this work was the study of the effect of different retanning agents on the waterproofing of wet-white leather produced by glutaraldehyde and syntan pre-tannage process. For that, a waterproofing process based in a waterproof fatliquor and a fluorocarbon based chemical, was tested applying different retanning resins, vegetable extracts and a dispersing agent to small leather pieces. Water resistance was evaluated by water absorption during 30 min in a static water bath at 25°C. It was shown that retanning agents reduce water resistance when compared with the standard process without them. The reduction effect is stronger when a normal retanning acrylic resin, natural chestnut extract, and a dispersing agent are used. The water resistance reduction effect of tara extract, mimosa extract, quebracho extract, melamine resin, dicyandiamide resin and styrene maleic resin is not so evident. This work needs to be continued in order to evaluate other retanning chemicals, pass to a larger scale and then evaluate the water resistance by the common methods of the tanning industry.