If you are looking for just dubbing, it sounds like you want to intentionally, completely mess up a fur-on-braintan.
Let squirrel come down to ambient temp. All of the 'passengers' will go looking for someplace warmer to live.
Skin it - long, underside center cut, then out the arms and legs. Unwrap the hide from the carcass.
Flesh it. With squirrel and other small creatures, these is easiest on your knee (with a towel) and a sharp knife. Scarp off everything that is slippery or shiny. When you get down to the actual skin, you will see a texture change and start to see the pores of the skin.
Wash in de-greasing dish detergent and rinse.
Get a bigger peanut butter jar or something similar. Separate out the yoke form 2 large eggs. Put the yokes in your blender with maybe half a cup of warm water and ZAP it on HIGH until it is good and foamy. Put fleshed skin and solution in jar, cover, shake well every hour or so. Leave it on the counter or someplace warm for 12 hours or so. Take the skin out and see how much hair is left on it and if that remaining hair will 'slip' easily. When the fur 'slips' easily, strip the fur from the skin. Put a coffee filter in a strainer and pour the slop threw it, rinse as needed and let air dry.
With the skin, dry it off as best to can and 'shoe shine' over a coated nylon wire of 1/2 dowel until dry.
Result: a pile of squirrel hair & small, fine piece of brain-tanned leather.
The foot of a nylon stocking is a good container to hold the fur when dying.
I was LMAO when I found this thread. My faithful bird dog, after seven years of chasing the squirrels in the back yard, finally got one. She learned to vector, I'm so proud. So now I've got this dead squirrel and a dog that is full of herself to boot. So I go inside to find the skinning knife and I look at this thread. Great advice given. But when I hit the yard, knife in hand, the little tree rat is gone. I guess it was playing possum. Oh well, I'll give the dog a C+ and either buy my squirrel or get out the pellet rifle. ROFL.
I give the bird dog an A++. A+ for determination and doing exactly what she should have done, brought it to you; not her fault YOU failed to shoot in first. (The second plus is for working out of her pay grade.. Squirrels are not birds!
Doesn't seem fair though. The dog wins. The squirrel wins, and you get to go on a wild squirrel chase for nothing.
Learned it as a kid. My uncle was a trapper I grew up in a hunting/fishing environment. Also learned about in some anthro glasses. Also learned about it when dealing with a "paleo-tech" and ancient-tech stuff.
Braintanning is really simple actually, and every creature does have enough brains tio tan their own hide. The good thing is you don't have to use actual brain. "Braining solution" is just a fat emulsified in water - egg yokes and crated up ivory soap or the two common substitutes. Oils tend to create an un-needed set of proplems.
At one point in time, near the end of the time I was forging steel in 900 AD tech, I had a really good blender and a really good food processor that NEVER saw food.
Bucking and braining a squirrel skin at the same time is a very good way to get the right size, shape and thickness leather to splice 2-piece atlatl darts togeather.