I have a lovely Ashton Freehand pebble grain, and for a while I was lighting it with a Zippo. (Now I light pipes with plateaus with matches.) Unfortunately, not knowing any better, this has left the raw looking, heavily textured plateau dark looking and sticky, as if covered by a residue. I'm not sure if rusticated is the right word to use in describing the remarkable plateau on this pipe; rather it looks cut right from the briar, with the rest of the pipe sandblasted. This is my favorite pipe--a hard judgement for most of us to make about any of our beloved pipes--but I'm not taking any chances, so I thought I'd ask the wiser heads here for advice on the best way to safely clean the plateau. Thoughts?