How to clean stone stained by slate cleaner/sealer?
Three years ago we had our interior travertine and exterior slate floors cleaned, polished and sealed by a 3rd party. The visible area in the back has light stucco, so any splash stains from the cleaner, polisher or sealer used are not visible. But later we noticed in the front, in a rarely visited part of the front of our home, the stone was stained damaged with whitish, light-colored stains by these agents per the attached photo.
Would anyone know the specific cause/agents of the staining from the slate cleaning, polishing and sealing process, and how best to remove the stains from the stone?