Machinery and chemicals have made the preparation of animal skin for human use a far less gory process in this day and age. But for hundreds of years, tanneries were relegated to the outskirts of a town because of the foul materials used in the process. Fresh from the slaughtered animal (cow, deer, rabbit or any creature with a workable skin), the skin would typically be stiff with gore, so the remaining flesh was scraped away, while any hair was removed by soaking the skin in urine.
Chicken faeces or other animal dung was then mixed with water in vats and kneaded into the skins by the tanner, who worked the leather into the vile concoction with his bare feet, like the way a worker would squeeze grapes at a vineyard. Animal faeces – especially that of dogs – contains an enzyme that breaks down the collagen in the skin, making it soft and pliable. In some cases, the mashed brain of the animal slaughtered was used to make buckskin or a fur hide, with the lecithin in the organ softening the surface of the hide. Finally, a tanning agent like cedar oil (or a similar natural tannin) was applied while the leather was being stretched in order to keep the material supple.