The question was regarding darkening, not charring. And any method of lighting can be used without scorching the rim.I find that using wooden matches for lighting stops the charing of the rim.
There is nothing sanitary about smoking. But a flame thrower can do wonders for ridding an estate pipe of germs.All this talk of saliva has me drooling for a fresh zombie-thread. The one about "thoroughly sanitized" estate pipes, perhaps?