X2

I use corn cob dust. It's not really dust but real fine cob grit. I get it from Research Mannikins. Live close to them so pretty easy to get. I only clean tanned hides nothing green or just dried. Add a little mineral spirits to each batch.
I've bought commercially tanned hides that have some of the same grut still in them.

It also works quite well in a brass tumbler. It does aa every good job shining up brass for reloading.

Be careful, if you look at some "sawdust" you will see it is actually very small cork-screw pieces of wood Do not use this material, you will never get it out of the underfur. I made this mistake once when I got some "sawdust" from a cabinet shop.
Since then I have purchased both sawdust and wood-flour from taxidermy supply companies.