Home Tanning Beaver Tails - Day 14 One of the unique features/challenges when working with beaver tails, is the difference in thickness from one end of the other. Before tanning, the tail feels too gummy and spongy for planing to be effective. Once the tannins have partially absorbed, the tail texture feels more solid, and planing is possible. Planing will help the remaining tanning go faster, and make the tail easier to work with after tanning. The most effective tool out of the planers I tried