General Overview of Ashing
Ashing is an important step in leather production.
Ashing takes place before tanning and serves to loosen the hair and epidermis (the outermost layer of skin) from the raw hide, making it easier to remove. Additionally, ashing prepares the skin fibers to absorb tanning agents.
The term "ashing" comes from the wood ash that was historically used in this process.
Ashing Process
The raw hides are placed in barrels or so-called mixers with an alkaline solution.
During the chemical process, the following happens:
- The hair and epidermis on the raw hide are loosened so they can be easily removed.
- The subcutaneous fat is loosened. Fats and proteins that could affect the quality of the leather are removed.
- The skin is "opened," and the fibers are loosened to allow the tanning agents to penetrate and bond with the skin.
- A swelling of the skin follows, which is crucial for the leather's quality later on.
Scouring / Scouring Treatment
Another process for hair removal is scouring or scouring treatment. In this case, the fur or wool is intended to be preserved. A chemical is applied to the flesh side of the hide, which penetrates the skin and dissolves the hair roots without damaging the hair. After ashing or scouring, the hide is called "bare."
Additional Sources (Accessed 15.01.2019):
- lederzentrum(punkt)de/wiki/index.php/Äschern
- leder-info(punkt)de/index.php/Äscher
- lederpedia(punkt)de/lederherstellung/aescher/aescher
