I have heard of people just soaking them in formaldahide (not sure of spelling) but I believe that is no longer available. There is some new and improved version now that is evironmentally friendly I am sure. I know one taxidermist in Okeechobee is ususing a pressure vessel. Says that if you put the head in with the mixture then put the pressure to it, it speeds up the time. Wish I could be more help.