I received two bear skulls from a friend who challenged me to repair them. He tried preserving them on his own, but they ended up looking pretty awful. They are cracking in several spots and still have a lot of grease coming out. I suspect he may have boiled them. Now, I am looking for some tips on how to tackle this new project. When doing my own, I have used Dawn to soak the skulls for weeks/months to remove the grease. I have heard that soaking in acetone can work well on more stubborn areas, such as the lower mandibles, is this true? How long would one soak in acetone, if this is true? Are there any techniques or products recommended for repairing a dry cracking skull and refinishing it? Thanks in advance.