I'm going to post this for @Zamb, mainly because he is probably the only person who might know the answer, but please, if anyone else has tried this and knows the answer, please tell me.
I'm been thinking of using a discharge dye on leather. I think that it could be a cool effect, and I could also play with graphics and color blocking. The leather is not drum dyed, so I'm fairly confident that the color will leach. However, I'm concerned that the treatment might leave the leather brittle and dry. Also, I have to do all this post manufacture, for logistical reasons.