Hi, All. I am in need of some advice. I have a few pipes that I've acquired that have some char on the rim. I'm not convinced that this is all burnt pipe, as this appears more "cake-like" and has flaked off in places to reveal uncharted rim. If possible, I would like to remove this "cake" from the rim (without damaging the pipe). Any suggestions? Or, should I just leave well enough alone? Thanks in advance.