For eight days I have had the skins in the water along with the alder bark. I checked upon the skins today and turned them, as parts were not totally submerged before. The skins show yet no signs of having soaked up any tannin, no change in colour whatsoever. I am beginning to think my solution is too weak. The ear skins are thinner than the leg hides, so I will probably take them out of the solution to dry if they show signs of changing colour in another week or so.
If I find time, I may add more bark to the solution at a point over the next days.