I had a hog skull de-greasing for over 3 months. The water it came out of was finally clear,so I whitened the skull and sealed it with paraloid/acetone . While it was drying the top of the skull turned yellow. My guess is that more grease came through when the acetone hit it. My question is what can I use to get the paraloid out so I can try finish de-greassing the skull? also what caused the skull to leach more grease since it all seemed to be out when I whitened it?