Fat tanning general
Tanning originated with the preservation of animal hides using animal fats. The craft gained a bad reputation in the Middle Ages due to the use of feces and urine in tanning processes due to a lack of preservatives. One advantage of tanning with animal fats is that after the animals are killed, the tanning agents are automatically available and can be used immediately. Furthermore, tanning with fats is a comparatively quick method, taking only a few days.
Fatty substances
Treating hides with animal fats does not always result in leather-like properties. Only fats that oxidize and thus dry out can transform hide into genuine leather. Some animal fats from land mammals do not possess this characteristic and therefore lack the tanning effect. However, other fatty substances, such as some vegetable oils (rapeseed oil, linseed oil) or animal fats such as brain, tallow, marrow, or blubber, can be attributed such tanning properties.
Oily leather
If the animal hides are treated with tallow or brain, it is referred to as "oil-tanned leather." During oil tanning, the leather is further preserved by smoking the hides. This method is relatively quick, taking only a few days. Oil tanning followed by smoke preservation was particularly well-known among the Native Americans of North America. It is also believed that Ötzi's clothing was oil-tanned.
However, leather tanned with brain, for example, has not undergone any chemical changes. As a result, the tanning agents remain washable to a certain extent, and the leather can harden upon contact with water. This is referred to as a non-permanent tanning.
Tanning and chamois leather
Chamois leather is leather tanned with unsaturated glycerides (tears). Tanning with tanning oil is primarily used for chamois and traditional leather. Learn more in our articles on tanning oil and chamois leather.
Additional sources (accessed 07.12.2018):
- leder-info(dot)de/index.php/Fettgerbung
- lederzentrum(dot)de/wiki/index.php/S%C3%A4mischleder
- lederpedia(dot)de/leatherproduction/tanning/fattanning
- leder-info(punkt)de/index.php/Hirngerbung
