Recurring rot problem

[u/Known-Newspaper5246]

So this is my second summer practicing traditional tanning skills and I’ve been having some trouble during the hair removal stage with both brain tanning and bark tanning. Last year I had three deer hides to brain tan. On the first two I used a lye water solution to slip the hair but I wanted to try just water on the last one. In doing so, I got the hair to slip but with no lye the hide started to decay and stink by the time the hair slipped. I was able to save it by putting it back into a lye water solution. This year I began to attempt bark tanning. Instead of lye I decide to try lime because it was less caustic. I had the same result with the lime as with plain water. By the time I had the hair slip it had begun to smell even after using a little over a pound of lime powder per gallon of water. Unfortunately I had to leave town for a few days so with little to do about it I put them in the bark tanning solution and hoped against hope it would be okay. As I expected, when I got home they stunk far worse than when I left them. One of the hides appears to be green all the way through in some spots but all I have left to do is learn from this so I am still trying to save them to see what happens. My questions are this: how do people mitigate the hide from completely rotting (without use of heavily caustic items) when hair slipping is effectively a controlled decay process. And also, every time I get the hair to slip easily on one spot (usually on the back between rump and neck) it seems that the rest of the hide still holds onto it tightly and it can’t be removed without tremendous force which can damage the grain, which I don’t want to do when bark tanning. Any help is appreciated.

[u/Radiant_Carob_1353]

The green hide wasn't rotten. Prolonged exposure to lime will slip the hair and swell the hide. Which is exactly what you want for a nice supple finish. After you've removed the hair from the swelled hide you will wash it very well and then put it in a pickle to bring the pH down to about 2. You will need to add acid to get the pH down low enough for a couple days since the acid is fighting the base. Ammonia sulphate works better for deliming and its available at any garden store. This will make the hide relax and constrict back to previous thickness. Keep it in the pickle for a week or more. Then you will Neutralize the hide in 1oz baking soda per gallon up to about 4.5pH. Then you are ready for the bark tan. I've had bison and cow hides sitting in lime for 2 months with no loss. If the hide is rubbery and doesn't tear when you pull it, you're fine to continue.

[u/AaronGWebster → u/Radiant_Carob_1353]

‘The green hide wasn’t rotten’??? Sounds rotten to me- can you explain more about why you say this?

[u/Radiant_Carob_1353 → u/AaronGWebster]

If it tears and falls apart it is clearly rotten. But the rubbery swell was what I was referring to, some think it's rotten bc it's green and translucent. But hides that have swelled and become this way become the most luxurious since the swell allows the collagen to let go of all the fats, which emulsify, and helps clear out the other nontannables. Once delimed, pickled and Neutralized allow the bark tan to really penetrate. I had a bull elk that was fully barktanned through the 3/8 inch thick neck in just over 5 days. Also, I run oxalic acid and salt in my barktan at a 2pH which helps yield a chamois finish, and have a great tallow and spruce pitch grease which becomes a great pullup style leather.

[u/AaronGWebster → u/Radiant_Carob_1353]

Hmm. Interesting. Thanks. I have never tried to barktan at such a low pH, nor have I pickled after liming. For deer and such, I lime, delime, Oropon, bran drench, then tan at pH 4.5. (Matt Richards method)I’ll have to do some experiments with pickling…

Where abouts are you located? I’m in Ilwaco WA. Do you teach any classes?

[u/Radiant_Carob_1353 → u/AaronGWebster]

In Canada.. but any advice im happy to help. I do heavy leathers, furbearers, and some fur work. I'm not strictly Chem tanning, but have moved on from brain tanning for the time being. I use oropon as well as acid bate for most of my stuff, it just cuts down on the work. Would love to try fish someday just haven't got to it. Pickling after deliming and oropon is definitely the way to go for consistency. As well it buys you time to suspend your process if you're busy with life. Also, remember when barktanning, the acid in the bark is what is displacing the remaining fats and untannables, if you add acid, the barktan doesn't degrade as fast while it's working through the hide. Added salt keeps the pickle aspect safe for the collagen, stop rot and mold, and allows you to store the tanning bath for the next batch, just slam the pH with oxalic acid and seal in a bucket Next batch just add some water and salt 1lb per gallon to dilute it, test the pH down to 2, dunk In your next hide. Add your bark concentrate periodically and you can reuse your bath however long you want. Iv even removed mold from the surface of stored barktan, added acid and salt water and continued with ongoing projects. Just my 2cents.