oh my. I'd have given them the hose outside! lol. yeah,,that would have stained any porous material.
I have a deep cleaner that my stone restoration guy recommended for my stone and marble (you know, cement tiles are pigmented w/marble dust and coloring) try this one and use it at a stronger ratio. after it's clean, seal again. if water is not beading up on the tile, it's not sealed enough.
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Fireplace
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