As they said above, plenty things will burn when in your bowl... pot, hair, paper, resin, G.I. Joes, etc etc..

Ash isnt one of them. The only thing to ever worry about with a pipe that involves ash is suck-through, depending on the pipe you have, which sucks balls.

Thats seriously a delay of game showstopper for me, I have to take a break if I get a mouth full of ash.