Here is a novel idea. Ronn Lucas has suggested soaking fatty duck skins in lacquer thinner. You can find his post by searching the board for 'lacquer thinner'. I tried this once with a duck skin and is seemed to work fairly well. You have to be careful with the container you use for this. Lacquer thinner will eat through most plastics in time. I ended up tossing that particular skin though because I let it get too rotten before I started processing it. The thinner couldn't get rid of the stench of death. So I'm not sure how it would have ultimately turned out.