I've tanned a few pelts. The thing to do to keep the hair from slipping is to try to keep the fur side dry. If it's got blood or yuck on it you can wash it with a mild soap or Dawn dishsoap, rinse well, and then use a blowdryer to get that fur dry immediately. Massage a warm brain slurry (1 part brain to 2-4 parts warm-not hot-water) into the flesh side of the fleshed hide. Let it sit for a few hours and do it again. Then scrape and stretch it dry. Do not stop till it's dry and no longer cool if you put your lips or cheek on it. If it's a thick hide you may want to let the brains stay on for 24 hrs. If you must leave it before it's dry, fold it along the length of the spine and try to match up the legs and all. Then roll up and put in a bag, in the fridge. It will keep there for a few days. If it doesn't soften up enough for your liking after it's dry, just rehydrate with brains and pull and stretch dry again. You can also smoke it after the first pull-dry to make it easier to pull-dry the next time. Smoke (or re-smokeif you already did it once). Do not put hide in a bucking solution such as lime or lye. This is specifically to make the hair slip.