Dear Rhonda and others: The cleaner I used to clear the black stuff off several headstones, including limestone, marble and granite is called, "CRUD CUTTER" manufactured by Supreme Chemicals Inc. of Atlanta, Georgia (800) 466-7126. They should be able to tell you what retailers in your area sell it. Again, good luck and best wishes for success! Sincerely, Kevin O'Brien Laguna Hills, CA Researching: Dorchester Gauley, Gillie, Lowe, Nelson, Perkins, Shannon, Smith ( Jefferson County, NY),Sundell, Van Schaick, Warner...