Mink don't have any fat, the skin should slip right off. If it doesn't take a sharp knife and gently nudge where it's sticking, careful not to poke holes in the hide. You don't have to buy tanning solution. Wash your pelt real good with dishsoapy water to clean oils & blood, rinse in cool water then put it in a solution of:
1 pound salt
1 gallon water
dissolve salt thouroughly then
carefully add 4 ounces battery fluid. Do not let the acid splash on you, however, once it's mixed with the salt solution it's neutralized and completely harmless.
Give your hide a stir now & then, it should be tanned in a couple days. Squeeze all possible tanning solution out (don't twist the skin tho) and transfer the hide to a solution of one ounce borax per gallon of cool water for 30 minutes to neutralize the tanning solution. Rinse really well in cool water. You're now ready for stretching & drying at which time you'll want to rub a little neatsfoot oil into the skin.
If you're not ready to tan it yet just roll it up in a plastic bag and stick it in the freezer 'til you are. Or you can stretch and dry it out.
Wanna see a marten hide trapper's hat I just happen to have finished yesterday? I had a friend give me a dozen marten hides so I made him a hat in return.