Looked at a tile floor yesterday. tested a small area on the grout cleaned up fine but there is a area where rug laid that has stained the tile I thought it was ceamic but lady told me that the tile is flexible never seen that before. Any chance to remove tried groutmaster on small spot but did nothing. I"m guessing rug off gassed with the sun shining down on that area and its permament. Sorry no pictures she told me about the tile after i left and she found old one in the basement.