I really don't know what this stuff is. The used it to stick up the tin tiles. Some of it crack off when we took the tiles down and we see a pure white wall underneath (maybe horse hair wall, as most of them in this house are). The odor smells something like must (it was very strong after we took off the tiles). This stuff is hard and cannot be scraped off. I just wondered if anyone knew what they use to use to adhere tin tiles to the wall and then maybe I could get an idea as to how to remove it from the wall. I want to put up wainscotting (bead board).