Tanning is simply taking an organ from an animal and preserving it so it will not rot. The skin is an organ and it will rot unless it is prepared right.
There are two main styles of tanning. Hair on and hair off. Obviously, for Head Mounts and rugs we want hair on. For leather to make gloves and saddles and things like that we want hair off. There are dozens, maybe hundreds of different types of tans. Each type of tan takes whatever will rot in a hide, like proteins, glues and such, and replaces it with things that don't rot. Skin (hide) is made up of lots of fibers. The tanning chemicals penetrate the hide and coat all these fibers, basically changing the chemical structure of the hide.
Elk Skin 200x
Elk Skin 60x
Elk Skin 60x
Elk Skin 10x
Some tans turn the skin white. Others turn the skin brown or green or whatever. Some tans are oil based, some are vegetable based, others are alum based. Some tans can be washed out with prolonged exposure to water and some will not. Tans can go on the hide in various ways. Some are a paste that is put on the hide, some are oils that are put on the hide, some are liquids that you soak the hide in and some are a dry powder that you work into the hide. Like I said, lots of different types. The vegetable based tans can take months to work. Other tans can take weeks. Some tans take only a few days to a week to work.
Right now, I use a tan called Lutan-F. It was invented by the Germans in World War Two. It produces a nice, garment grade leather. In the past I have used both Salt-Alum and Dry Preservative quite a bit. I don't really like the Salt-Alum tan because it produces such a dense leather. It was the tan I used when I was first learning Taxidermy and has been used for hundreds, maybe thousands of years. It's a good enough tan, but I like Lutan-F better.
I like Dry Instant Preservative. It's a dry powder and is worked into the raw skin. Some people may say that the Dry Instant Preservative does not actually tan the skin. I disagree. I have several deer skins that I have used it on. I let it sit on the skin for several weeks and then I rehydrated the hide, oiled it, and worked it (Broke it) till it was soft. It sure looked tanned to me ! Others may fell differently. So why don't I use it anymore ? I just like Lutan-F better.
I'm experimenting right now, with some very promising paste tans. I'll let you know how it goes.
One of these days I'm going to try the old Indian way of tanning. Brain Tanning. From what I can gather, you take the brain, add water, mix it all up and cook it a bit. Then you take a well fleshed hide, and work this brain mixture into the skin. The oils in this brain mixture penetrate the fibers of the skin. As the skin dries, you work it and work it. This breaks all the skin fibers loose from each other. Once the hide is completely dry and broken, you put the hide in a tent or some kind of enclosure. Then you channel smoke from a really smoky fire into this enclosure. The smoke coats each skin fiber with creosote, making it waterproof and giving it a nice light brown color. Apparently this works quite well. I have brains, well, deer brains anyway, and deer skin. What I don't have is time. If I ever get around to it I'll let you know how it turns out.
In the old, old, days they used crushed bark for tanning. This took as long as six weeks. In the old days they used arsenical paste. This worked great as long as you are very careful ! I read a story about an early hunter and taxidermist in Africa. While collecting specimens for a museum, he had shot a leopard. He came up to it thinking it was dead. It was not. In the exciting minutes that followed, he killed it with his bare hands. In that process the leopard bit his thumb off ! He sent the thumb, preserved in a jar, to the museum in the next shipment of hides. Kind of a joke ! Not to be out done, the museum people noticed that his thumb nail had a discoloration due to arsenic poisoning. they told him he needed to be more careful ! Hard core boys, these.
All the tanning chemicals I use are quite safe. However, I still use rubber gloves, safety glasses, etc. just to be safe. I guess I'm just not dedicated enough. I'm not willing to die for the glory of tanning !
The drill is this. After skinning off all the meat, fat and doing all the fine detail skinning, the hide is salted with fine salt. This is called curing the hide. It must be cured for at least 48 hours and it can sit in the salt for years. You then pickle the hide in an acid bath, using one of the new "Safety Acid" pickles, to remove proteins and glue. Then the hide is neutralized with baking soda and weighted. The proper amount of Lutan-F solution is made up and in goes the hide. It sits in the tan for several days till it is tanned. Then it is rinsed in cool water and allowed to dry till it is moist and then it is oiled. It is now ready for mounting. This all sounds very easy and quick but it really isn't. I spend a lot of hours preparing hides for tanning, tanning them, and then preparing them for mounting. There is a lot of detail work involved.
I've always tanned my own hides. If you have your hide tanned by a big tannery, and you want to mount it, you will need to re-hydrate the hide and either mount it immediately of freeze it in a plastic bag. If you read the fine print you will find almost all tanneries say to mount the hide within six months or so. I have mounted a number of hides that have set for one to ten years after tanning. They all were kind of rubbery after re-hydration. This made them real hard to mount. One was a cougar skin and I just could not get the claws to extend. Another was a caribou. It's wonderfully soft hair seemed to be growing out of a piece of springy rubber. I was able to mount everything but it works much better if the hides have not set around for too long. Remember, most tans change the chemical composition of the hide. Each tannery will be using their own version of what works best for them. Read their tanned hide care instructions and follow them !
I feel another problem is the marking system most tanneries use. It's just a bunch of holes in a pattern. What if someone else uses your pattern ? Getting the wrong hide back must happen more often then the tanneries let on, because a number of customers have told me that they have gotten the wrong hides back. I tan each hide separately so there is no danger of getting them mixed up. I never reuse any tanning solutions, although I suppose you could. I figure each hide deserves it's own new, fresh, tanning solution.
You will find there's a lot of MACHO mixed up with all this skinning and tanning thing. Why I don't know. It's just a hide ! Lots of testosterone here. I guess it's like an Elk in rut. Pee's on the ground and then rolls in it ! Oops, I've said too much. The tanning guys will get mad at me !
I thought about putting up one of those sneaky, pop-up ads to get people to come and buy a Bear Skin Rug from me ! but I figure this little blurb ought to be irritating enough, Right ?