Before modern technology gave us machines and chemicals to tan animal hides, early civilizations used natural ingredients to preserve animal skins. This traditional way of tanning hides is used today by people who want their animal skins tanned without chemicals.
Since the Stone Age, animal brains have been used to tan and preserve animal hides. Frontiersmen wore brain-tanned buckskin, as did General George Washington's troops during the Revolutionary War. The work clothes of common laborers in 18th century America wore tanned buckskin as did the fashionable upper class in Europe.
First, you must scrape the animal skin to remove all fat and membrane. The brain of the dead animal is removed, heated and blended into a brain-and-water mix called a slurry. After the animal is scraped, the slurry is rubbed into the hide and left overnight. The slurry is scraped off the following day.
The brain method of tanning preserves the animal skin and leaves it soft and supple enough to wear as a garment and lasts as long as chemically preserved hides.
Contrary to what many people believe, an animal hide preserved with the brain-tanning method does not have a bad smell.
Chemical tanning methods leave chemical residue in the animal hide that can transfer to your skin. Brain-tanned hides have no such chemical residues. In addition, brain-tanned hides can be washed.