North american indians frequently used the brains from animals to tan their skins. During the leather course, two types of hides were brain-tanned, those with hair left on, and those with hair removed. Raw and cooked cow brains were used, both types producing very soft, pliable leather. The staking phase (when the skin is pulled in all directions until dry) was hard work but essential to produce good results. It has also been found to be a vital stage in restoring/conserving such skins.