Scoured and Tanned Leather

Cooking is not the only thing the Cauldron is used for. You can also tan Leather. This process requires leather to be put through a Mill Stone to get Scoured Leather, and then put into a Cauldron with either Dung or Bark. Throwing Scoured Leather and either 1 Dung, or 2 Birch Bark, results in Tanned Leather:

Tanned Leather can be crafted into leather armor, which is four times as durable as regular leather armor, and cost far less than traditional leather armor.