Fortunately, I've never faced that problem, not even with my 25-year old S&W Model 41. However, a company called "Formby's" makes several kinds of great fine wood-finish products. Their Lemon Oil did a wonderful job of cleaning up the finish on a pair of Italian-made speaker cabinets I have. They're Opera Callas monitors, which retailed for close to $3K per pair and have handmade wooden cabinets. I figure if Formby's can help those, it ought to do wonders for a good pair of grips.