In this segment we finally begin tanning the skin. Vegetable tanning is one of the neatest things I've ever learned. This is the most exciting part where the hide fiber is transformed into leather. Leather is not skin or tannic acid, it's a unique material made of the marriage of those two. It can be left in the weather for years, and though it may become moldy and damaged it will not rot away for a very long time. There are pieces in my compost piles that I pull out and throw back in every year just to see how long they will last. The first piece of leather I tanned was a rotten piece of skin that I should have buried, but I had some oak bark sitting around so I made a solution and tossed it in. The tan almost seemed to heal up rotten parts of the skin and knit them together. I still have that piece of leather. I left it hanging in a tree outside for a year or two once, but it appears pretty much unfazed.
In this segment we repeatedly rinse and scrape the skin to remove lime and unwanted gunk, then soak the skin in an acid drench made from fermented bran and water. Oak bark is prepared by chopping and cooked to make the tanning solution.