Hello, I bought a wallaby skull that had some grease in it: Before: I soaked it in straight ammonia for three weeks; some grease came out (the ammonia went yellow) but unfortunately some of the sutures widened. I am afraid of damaging the skull. Here it is now: I put the zip tie on it yesterday to try and stop it from opening more. Not all the grease is gone, as you can see. What should I do? Put it in fresh ammonia for a while more? Put it in 3% peroxide for a day? Leave well enough alone?