Have a toilet in a house 30+ years old with black deep in the bowl. At 1st thought it just needed to be cleaned but that isn’t it. I guess finish has worn off. I know tubs & sinks can be refinished but never see anything about commodes being refinished. Bathroom needs a lot of cosmetic work that I can’t get to now (neither time nor money). As a temporary solution, can the commode be refinished or touched up in some way either by myself (with Klenks) or by a professional? It looks gross and dirty.