Content: To reduce the environmental impact of tanneries at source for all types of leather, a series of investigations started at laboratory, then large pilot scale, to rationalise liming and tanning processes. This included the elimination of washes at the end of these processes, with retention of residual processing floats at maximum concentration as a chemical resource for reuse in subsequent processing. Adopted by four tanneries manufacturing more than 70,000 hides per week to the chromium tanned state, analysis detailing the equalisation of ions and solubles within these closed-loops was possible, and the subsequent release mechanisms. Large scale wet blue units specifically built to match the technology are now in the final stages of construction. From foundation level these differ from normal design, also uses of equipment, management of discharges, and plant operation. Low-impact chemical processing is locked into the fabric of these new tanneries. The technology has also spread to large scale nappa sheepskin production. And at cottage scale, thirty small tanneries in a tanning cluster processing sheep, goat, and bovine leathers to the wet blue are already changed their processing to meet a policy of no chromium discharges from their tanning areas by June 2019. The aims of low-impact manufacture, where the use of active chemicals is complete, quality fully maintained, and waste minimised are being met. This new approach to leather making offers considerable benefits at both large and small scale for wet blue manufacture. Take-Away: Closed loop systems for liming and tanning are highly effective in leather manufacture. Hight quality leathers can result fron this technology. There are considerable savings in chemical use and minimisation of waste water treatment.