Grout haze is caused when tiles are installed and the grout is not completely removed from the tile surface after the project is complete. To clean it, you can use common household ingredients or a commercial tile cleaner. The best time to remove grout haze is within 24 hours of completing a grouting project; however, it is possible to remove haze even days or weeks after the tiling project is finished.
It's always best to start with the simplest removal method first. If you're trying to remove the grout haze within that first 24-hour window, plain elbow grease may just do the trick. Fill a bucket with warm water and, using a green scouring pad, give the haze a good scrubbing. For stubborn haze or haze that's had a little more time to sit, this may not work.
If your grout haze refuses to come up with just warm water, try a mixture of warm water and vinegar (50 percent of each). In many cases this will remove the haze, provided you use enough force against the tile to remove the excess grout causing it.
By this time, if the haze has still not been removed, then it may be time to resort to a commercial haze remover. You can purchase this type of product at any large home improvement center in the tile department. Following the instructions on the package and wearing protective gloves, soak a cloth and use it to wipe the haze from the tile. If the haze continues to be a problem, then the next step is to try applying the remover directly to the surface of the tile. Take care when resorting to this measure that you try small amounts at a time in small areas to avoid possibly damaging the grout you want to keep. Also, be sure to clean up the remover thoroughly, using a new cloth if you have to.
Again, keep in mind that the longer grout haze is allowed to set, the harder it will be to remove.
What Not to Use
The primary products to avoid when attempting to remove grout haze are commercial detergents that may be overly harsh on the grout and leave their own film on tile.
Be aware that attempting to remove grout haze may actually soften the grout between the tiles. If this occurs, then use a putty knife to smooth the grout into place and then reseal the grout to prevent further damage.