I was looking through a catalog of plants that contain tannin, and wouldn't you know hops have a bit of tannin in them about 2-5% tannins by weight. My brother home-brews and has quite a field of hops growing at the moment. I wonder if it would be possible, with enough hops, to make an extract that you could then use to tan hides. Is it feasible? How much would I need to boil down for a standard deer hide?