I’ve messed around with different ways of bleaching skulls. The best way I’ve found it making a paste of peroxide and borax. I paint it on the skull and re apply every couple days for a week. They always turn out alright. I think it helps putting borax in the water while it’s boiling. If you do a bear skull it’s a lot more greasy than a deer skull. I’ve submerged them in peroxide before and that works too, it uses a lot more peroxide though. I’ve tried the higher % peroxide and the cheap stuff at the dollar store. I honestly couldn’t tell a difference. Im amazed at the people that pay somebody to do their skulls. It’s really not that big of a deal if you cut off as much material as possible before boiling.