Epoxy Removal (black grout stains) from Unglazed Products
The film of epoxy grout will not come off with an acid cleaning. The epoxy cures quickly and cleaning needs to be attempted within no more than 48 hours of grouting sooner better.
When using a dark grout on an unglazed paver or unglazed quarry product the tile should be sealed in advance with a penetrating sealer. The sealer will not change the tile appearance but it does fill the minute holes in the surface that will trap and hold the dark grout. If the tile was not sealed it will likely have discoloration that may need to be removed. The success rate with this type of stain will probably be no more than 90%.
From your supplier obtain and use a heavy-duty stripper or a sealer and adhesive remover that is compatible with the product you are going to clean.
- Work the stripper with a stiff bristle type of scrub brush or a nylon-scouring pad. If the stains are stubborn try steel wool.
- Clean the area with a household cleaning product and scrub vigorously with a scrub brush or power floor scrubber.
- Rinse the area thoroughly, repeating as may be required.
- Using lacquer thinner, dampen a cloth and apply the thinner to the epoxy film. Using disposable cloth pads or rags, promptly remove the softened film from the tile surface. Repeat as needed until all traces of the film are no longer visible.
- For heavy coatings of epoxy use a heat gun to soften the coating and scrape off or rub off until the film is no longer visible.
Recommended book: Tile Council of America Handbook of Ceramic Tile Installation.
