hi loader
Never used arm and hammer only boiling water. Make sure the antler does not contact the water or it will lighten in colour. As for bleaching??.well once mine have boiled off the flesh I pick whats left the let it dry for a week. Then i fill the skull plate cracks with poly filler light sanding the paint it what ever colour of white you like ........flat....... gloss

see what they look like here....not the best picture

http://forum.hunting.net/asppg/tm.asp?m=785425