A short history of the tanning process. Only three tanning processes were known until fairly late in the 18th century: 1) fatty materials such as brains and marrow used in conjunction with smoking; 2) alum and salt, often in conjunction with fatty lubricating materials; and 3) vegetable tanning solutions in which skins were steeped. With the coming of the Industrial Revolution came an incentive to speed up the process; tools were improved, new materials imported, active ingredients in traditional materials such as dog dung explored and finally isolated, and chrome tanning came into use.