Brain tan the Sioux way was the book I learned with. Crazy Crow should have it
Brain tan is how most primitive peoples tanned skin. The green skin is stretched as far as possible often on a frame, then the hair is scraped off, all the fat and membrane on inside scraped off too.
An animal fat, often boiled brains was used, hence the name, though tallow or lard or beats foot oil work well, was rubbed in to both side of the hide. It then taken off the frame and kept moist over night. One can cover it with wet towels or even soak in a bucket of water.
The next day re stretched and as it dries you ‘work the hide’ you want a baseball bat sized branch of wood with a screwdriver or axe shaped but rounded end three or four inches wide and from both side you go all over the hide in every which direction stretching and relaxing the skin.
This is the hard part as you have to stay dedicated to the job. And on a warm day it take three or for hours to dry.
When done and DRY it’s velvet soft and ivory white.
Now you make a cone of dowels or saplings and hang the skin on it. In side the cone you make a small very smoky fire.
I used to have two so three white hides and smoke them at once. I would make a pit. Build a fire in it. Dig a small trench and put the cone over one end. Cover the fire and let the smoke go through the trench and out through the cone. Turn and move the hide so you get it all smoked. The longer you smoke the darker it gets.
Hickory or sumac makes a grey color, oak or walnut makes a brown, cedar smells real nice and pine too, makes it a yellow.
From animal to leather is three days.
The green skin can be fleshed on the inside then put a a non metal water container with hardwood ash and water for a couple of days. This will cause the hair to slip and you can scrape it off with a knife leaving a smooth side.
Then you can make a five gallon non metal bucket and make a solution of Kosher salt or sea salt and alum. One pound BP per gallon each. Soak the hide in that. Twice a day pull the hide out and then replace so as to have no folds where the solution isn’t getting too well. After a week or so cut an edge of the skin. It should be white all the way through if done. If not it will be white on the edge and gray in the center. Do this at a thick side like the neck. Just to be safe go a couple more days.
Pull out. Rinse with water and let hang over night. In morning when stlll damp ‘break the hide. A 2x4 with a flat sharped edge that half buried in the ground and high enough to work back and forth over works well, and continue to work skin over until dry, about two to three hours. Then treat with neets foot oil.
Bark tanning takes several months.
You need a non metal trough, water proof pits were dug in the old days I used a fiberglass water trough. This need be done in warmer weather.
The inner bark of oak is used and shredded layer about an inch thick is laid in the bottom. Skin laid out and covered with the bark. Have in a sunny spot, cover with water you want a thick black bark tea. Leave it about six months.
Your solution is too high in tannic acid for bugs to grow in it. Keep a couple of buckets of bark tea handy to add as the trough evaporates, don’t add just pure water.
Place this down wind of your house as it smells strong of the bitter tannic acid. Tanneries were built down wind of town.
When done, pull out wash and treat like the alum tan. This makes the strongest leather
Get some books
And watch some you tube vids.
Lot of work but it is fun.