Bill, We have honed 12x12 white marble tiles which were sealed on the backside as well and the front before installation. This has resulted in the marble failing to adhere to the thin set and separating from the wall. The tiles are in perfect condition but obviously in order to reinstall them the sealer on the backside must be thoroughly removed. Can you suggest a product which would do this job? If there isn't a chemical product to remove the sealer what means are available for this task? Thanks so much for giving me some advice on this matter. We need to get it done urgently. Sincerely, Bonnie Gallogly