We've been macerating deer skulls for about 4-5 years now. We process around 50 each year and have good success with them. We use an old chest deep freezer with a light bulb on a thermostat set around 100 degrees. We can have a clean skull in about 6-7 days. Freezer by Tnrandy posted Apr 24, 2020 at 10:22 AM Most skulls come out of maceration clean and pretty white, after degreasing they look good before going into the peroxide. Here lately we've had skulls come out of maceration with dark spots here and there, and even going through degreasing, heated ammonia, and dawn, back and forth for a few weeks, they still have the spots...they just won't come out until we put them in peroxide. The peroxide finishes them and they come out white and stay that way. I know its not grease, it looks stained, and sometimes it's got a green tint to it like mold. Any suggestions? Like I said, the finished product turns out great, but I just don't like seeing those spots before they go into the peroxide.