Salt-Acid Tanning
Prepare the solution as follows:
Dissolve 1 pound of sodium chloride (salt) in 1 gallon of water.
Carefully add 1/2 ounce of concentrated sulfuric acid to the salt solution....never add water to the Acid!! (Caution: Sulfuric acid is very corrosive and must be handled with care. Avoid contact with skin or clothing. Store acid and the finished solution in glass or earthen containers--never metal.) When adding acid to the salt solution, pour in slowly with constant stirring. If the acid or mixture contacts the skin, rinse immediately with a solution of bicarbonate of soda.
Addition of the acid generates heat; the solution is ready for use after it has cooled.
Place the skin in the salt-acid solution so that it is fully covered and allow it to remain for 1-3 days with periodic stirring. When tanned, remove from tanning bath, rinse in plain water, rinse a second time in a solution of borax or soda (1 ounce per gallon of water), and finish with another water rinse. Squeeze out excess water, stretch, allow to partially dry, Stretch, and when nearly dry, work the skin by rubbing and pulling over the edge of a table, as in polishing shoes with a cloth. Stretching and working the skin is necessary for softening the finished skin. If the skin is rough, it can be sanded with a coarse sandpaper block. A thin coating of Neat's foot oil, glycerin, or other leather conditioner improves pliability.