How do you patina warthog tusk?

[Gahagan]

I have a set of damascus push daggers ordered by a customer the handles are to be made of warthog tusk. I want to add a patina to them, currently they are bleached white, to make them look more antique. I just dont know how to go about doing so or how to finish them. I know some of you have done this before and I would like your feedback on this if possible.
Thanks

 

[LRB]

Soak it in Fiebings med brown leather dye. The spirits type. May take half a day or more to get a lasting penetration. Experiment with a piece of scrap.