boiling is the worst. so is bleach. boiling drives the grease and fat into the skull. bleach destroys the bone. after a few years the grease works it's way back out and looks bad. there are lots of secrets they use in the business. the best way is to send it to the pro's. if you are happy with what you did that is all that counts. just remember, it won't stay that way long and once it falls apart you can't get it back. if it is a "once in a lifetime trophy" get it done right.