I will try the Borax method. I have had several suggestions. I used a little bit of dish soap in my boiling watter but I don't think it helped at all.
I've bought some 35% peroxide cream to put on the skull. Instead of soaking the whole thing, I figured I could apply the peroxide cream and let it sit on the skull for several days. I will still cover up the antlers to protect them -- I don't want to have to "fix" them with wood stain... )
