Started yet another project yesterday. The ear skins and two of leg hides of an elk (moose) were thawed and the excess moisture was soaked up by the snow.
I scraped the bark of two alder trees off with my cannon bone flesher. It is very effective for that purpose and even shreds the bark at the same time. I gathered enough bark to about equal the weight of skins.
The bark was distributed evenly on the flesh-side and the skins laid in a stack.
Lacking a waterproof primitive container I decided to cheat a little here, please bear over with me. I used a empty ice-cream box, put the skins with the bark on in, filled it with water and have now left them to soak up the tannin with the lid on to conserve moisture. I will leave them for a few weeks, but I do a check every now and then to see how it goes.