Taken from the" Landscapes of Memories". A highly recognized government of Ontario booklet on repairing[tombstones] stones.. by Tamara Anson-Cartwright. Page 15 Column 1 paragraph 4 " It is important to be sure about the motives of cleaning stone. Cleaning is expensive and can cause damage, if is not carried out with appropriate expertise. " Column 2 paragraph 2 " .....it is best to hire only skilled stone masons and conservators with extensive professional and expertise in this specific area." There is only one other person ( in my opinion) who is expert other than , the author of " Landscapes of Memories " . That person , whose view I greatly respect is Bill Gilchrist. If Bill would like to give his opinion to this list , he is most welcomed. Other than Bill's anticipated e-mail, this subject is now closed. Thank-you to all members for your co-operation on this matter. Sheila List Mom