Leather is a popular material - be it for the manufacture of shoes, bags or furniture. However, production, or, more precisely, the tanning process, is very inefficient. The chrome tanning agent used is only bound between 50 and 70 percent in the leather. On average, 40 percent ends up in wastewater and can only be recycled at great expense. Fraunhofer UMSICHT has therefore set itself the goal of completely avoiding excess chrome tanning agents and chromium-laden waste water in the tanning process. The sustainable and cost-effective tanning process CLEANTAN® was developed within the framework of several projects funded by the BMBF.