Ive been doing the CCH thing for a few years, (close to 20). Anytime I hear about using leather or horn/hoofs in the CCH mix, I chuckle and move on. I dont think any serious practitioner of CCH, or any manufacturer would use those sorts of products in their CCH.
Hooves and horns are made up of Keratin, the same thing hair is made up of, leather is primarily Collagen and Elastin, neither is a good case hardening compound.
Theres several different ways to tan leather, chromium salts, vegetable tanning, brain tanned, each one has different chemicals which will change the outcome.
Horn/hooves? Just the sheer amount of crap thats in them rocks, nails, dirtand literal crap that makes them a bad choice
