There's something I have noticed on a few occasions now, and don't quite understand the cause — suppose I let my pipe go out, tinker for some 20 minutes and get back to smoking and then relight. The taste is suddenly sour, the smoke is choking, feels as if I were inhaling ashes. It completely ruins the whole thing, I usually just go and dump when this happens. Not sure if tobacco is relevant — smoking Danis Black Vanilla at the moment. Any ideas on why this is happening and how it could be prevented? edit: Could I ask a moderator to move this thread to the "Pipe Smoking Advice" forum?