We had a ceramic tile entrance foyer and hallway at a preschool which had a "sealer" applied several years ago. We tried various companies and different processes, and we were never able to get it clean. The Koshgarian crew came and really worked hard, even doing final touches with a hand scrapper. Needless to say, their efforts worked and are appreciated as we now have a gleaming floor that we are proud of. Thanks Koshgarian and the crew who worked so hard for us.