QUESTIONWe have a dark pebble and dark grout shower floor. After 6 months, the dark grout has turned bright white and nothing works to remove it. Tried cleaners, vinegar, scrubbing. We were told by the tile store to use grout with a special sealer mixed into it and then seal the floor afterwards, too., when thoroughly dry. It was carefully and painstakingly installed. We even sealed the stones separately before any other sealing.
The floor looks horrible and is getting progressively worse. How can we remove the "efflouresce "? And then what.....reseal with a different sealer?
ANSWERANSWER - It is not clear what kind of sealer you used. Normally sealers are not mixed into the grout when you install the grout, so that may be part of the problem?
Grout turning white can be caused by efflorescence which is the calcium from the water and the underlying concrete or mortar migrating up through the porous cementitious grout. Excessive efflorescence is considered a symptom of an excessive moisture problem. If the water isn't draining away properly in the shower pan that cause be the cause of the excessive water that is causing the efflorescence. If the weep holes in the drain or if the waterproof membrane in the shower pan isn't sloped properly to the drain that can cause water to not be able to evacuate. The only way to determine if this is the problem is by either intrusively removing tiles to inspect the underlying conditions. You could let the shower not be used for a few days and monitor it with a moisture meter to see if it dries out or not.
If the while condition is actually efflorescence then it should be able to be removed with a slightly acidic solution like vinegar, which should only be used as a test to verify it is efflorescence. If it is efflorescence, then purchase a tile cleaner that is made for removing efflorescence. Removing the efflorescence does not solve the problem, since it is the symptom of the problem, so it will likely return.
You could have latex leaching where vinegar will not remove it. You can test this out by buying a tile latex leaching remover and seeing if it works.
The other condition that can cause grout to turn white or cloudy is if water is trapped under the tile and the grout is sealed with a non-breathing sealer. If this is the case then you have to remove the sealer if it is a surface sealer. If the sealer is deep into the grout then you might have to replace the grout. There are grout colorants where you can paint the grout color a different color and it seals the grout at the same time, which is another option to consider. But again, you are treating the symptom of the problem and not the problem.