I'm trying to brain tan my own hides but am unsure when I have fleshed down enough for the brains to penetrate proper. I did it wet with a dull knife, and took off a good layer mostly in one piece. When I started I could pull the membrane 1-1 1/2" from the skin, now they is a tiny bit, just enough for me to grab and pull it just a little. Does that have to come off too???
I cracked the skull for the brain but found so little I couldn't imagine it covering the whole thing. I think I will just wait until we butcher a cow or pig this week and harvest that for my needs.

Not sure if this will help because I did mine with the salt/alum method but after soaking the hides in the brine for two days I was able to peel the membrane off fairly easily in the thicker sections and with a bit of scraping on the thinner areas. The skin itself is very thin so a lot of care must be used when scraping but the texture of the skin is different than the membrane and fat. I've never done the brain tanning but I would think that it must be clean right down to the skin for it to be most effective. Hope that helps a little...

Truckinguy, do the reds hold up in alum tanning? I was thinking of doing the sulfuric acid method, since Eco2pia said the flesh peels off of the skin that way, but the reds aren't stable enough to hold up -- they brown a bit.

Since you say that you were able to peel a good bit of the hides after soaking in brine, maybe I'll do that instead, if the reds stay red.