How to Remove Vinegar Stain on Mosaic Tile
Q. I was reading your Stain Management Application about cleaning vinegar stains, and in the types of stains on the left, vinegar is not listed. I was hoping you could clarify what poultice and method to use. Vinegar diluted with water was used in an attempt to clean new, unfinished natural stone mosaic floor tiles (like river rock). It's yellowed so I'm hoping to remove the stain. The texture (finish) of the stone was not affected at all, just the color. I don't think etched or anything. I think it's fairly porous. They appear to have been tumbled and ground at some point to flatten them and take the edges off. (I'm an architect and have worked a lot with tile and stone, though haven't come across this). I put the same vinegar mix that was used on some leftover samples and tested my sealer on it. It appears to mask the discoloration. I have 2 sealers on hand. one is enhanced providing a wet look which seems to do a pretty thorough job. ( I can't see the discoloration) The other is a penetrating sealer that leaves the natural finish appearance alone. Obviously the latter is out. I'm almost afraid to do anything more to the natural stone for fear of creating more problems. The only remaining question is if the dried vinegar would affect the sealer over time. After 36 hours, I can't see the discoloration at all.
A. If your mosaic tile is marble, then the problem is likely etch damage. The acids in the vinegar reacted with the calcium in the marble, creating the discoloration. You can try buffing with a honing powder and then cleaning with a stone-safe, pH-neutral cleaner. If your stone is not marble, but river rock, then the discoloration is likely due to the vinegar reacting with a coating on the surface. The stone will need to be stripped and recoated. In either case, we highly recommend leaving the restoration work to a qualified stone restoration contractor. If you are having success with the sealer, this is promising. The dried vinegar will not cause a problem. Once the acid in the vinegar has reacted with the stone, its acidic properties are gone. If you are unable to completely resolve the problem, and have need of the services of a Certified SurpHaces PRO Partner, please contact us.