Why Bark Tan?

Driftless Tannery has switched over to using bark tanning as our main method of tanning hides. Why the change? We feel that the bark tan produces a more consistent and superior product. Up until this point we used Alum to tawn our hides. What does tawn mean? The process of preserving hides with alum and salt is not a true “tan”. True tanning happens when you use tannins from trees or other vegetation to alter the skin’s chemistry and preserve hides. Alum tawning produces lovely, white supple leather products that are perfect for indoor use. Alum tawned hides are well preserved and long lasting. Garments tawned with alum and have even been found in tombs in ancient Egypt.

So why switch? Alum tawned hides are not water resistant. Hides tanned with bark are. Now, we have used our sheepskin around the house for years and have never needed to throw them in the washing machine, but life happens. Someone might find themselves needing to wash their sheepskin. If you do that with an alum tawned hide, you will have to oil and work the hide again in order to return it to its original soft, supple finish. Some people don’t have the ability or the knowledge to do that.

We use Mimosa bark to tan the hides at Driftless. Mimosa trees are a part of the acacia family. These trees are often thought of as weeds as they reproduce rapidly and can crowd out native plants. In our opinion, that makes them the perfect trees to harvest for tanning.

Items tanned with Mimosa will have a light salmony color on the leather side. We work hard in our process to rinse the tannin out of our sheepskin so that there is very little change to the color of the fiber. You can see examples of the different shades of leather in the pictures below. The photo on the left shows the leather of a bark tanned sheepskin and the photo on the right shows the alum tawned leather. Notice the fiber on both hides retains their natural color.