Hello!
Today, I tore out a fireplace with an accompanying insert. I removed two tiles at each end of the floor that the fireplace was on with joint compound and sent them for analysis beforehand, since the house is from '65. The results were negative. It looked like they set the tiles in regular mortar, it didn't look like adhesive, but the joints could, of course, contain asbestos. When I had chiseled away the elevation that the fireplace was on, I saw that maybe 10 of the tiles had a white coating underneath, not the gray that regular mortar gives.
Upon further inspection, I saw that these approximately 10 tiles were set with a very thin layer, about 1-2 mm, of some white mortar on top of regular mortar. They were completely random on this elevation. I thought it could be some form of lime efflorescence, which made the outermost layer of mortar white?
The surface area is about 1x1.5m, so it seems likely that they set all the tiles on the same day; I can't believe it would be adhesive applied in a super thin layer on top of the mortar??
I'm just curious if anyone has seen something similar; everything is gone, so the damage (if any) is already done, but maybe one can learn something new anyway.
