Ideally, the final wipe-down will take place after the grout has been allowed to cure for 24 hours. However, grout haze could still potentially be removed within a few days. When it becomes impossible to remove with a sponge, it's time to call The Grout Medic for tile cleaning to eliminate the grout haze.
Sponge the surface
Once the grout has started to harden (20 to 30 minutes), begin sponging. Don't use just any sponge, especially one from the kitchen; choose a “hydrophilic” sponge. Make sure the sponge is damp, not wet, and sweep diagonally across the face of the tile and wipe the grout off the tile surface.
Before trying to remove any haze, make sure your tile surface is totally dry. About 24 hours are usually needed for this. To find out how long it will take, check with your installation specialist or, if you did it yourself, the grout's package. However, you shouldn't leave grout haze on for longer than 10 days.
Wait 24 hours for the best results
Though contractors may tell you to wait at least 12 hours before using your new tile floors, household members should wait a full day before walking on or grouting newly-installed tiles for optimal results.
The standard cement grout commonly found in most hardware stores and used in most residential homes takes around 48-72 hours to cure. But it is worth pointing out that you need to know how to mix grout the right way. If too much water is added it will obviously take longer to dry and won't do its job as well.
Grout Must Set and Cure
That usually takes between 48 and 72 hours. If you can avoid walking on your floor for that amount of time, that would be ideal. Once the grout is fully cured, you can walk on your new tile flooring with no concerns about damaging it or causing tile pieces to shift.
They say it's “grout haze:” the silent enemy that can ruin any beautiful tile surface, which doesn't discriminate against color, material or size. It can strike any floor or wall — from porcelain to natural stone. Some grout haze problems result in the worst scenario of all, “picture framing.”
Make sure your tile surface is completely dry before you attempt to remove any haze. This typically takes about 24 hours. Consult your installation professional—or, if you DIY-ed it, your grout's packaging—for the exact amount of time. But do not wait more than 10 days to remove grout haze.
The shortest time after laying tile that you can grout is 24 hours. However, it is much better to wait at least 48 hours before grouting. This is to give the mortar ample time to set and dry before pressure is applied. Choose a nice and dry day to lay your tile.
New grout can take 24 or even 48 hours before it dries completely. It depends on the humidity and temperature in the room where the grout is installed.
Remove Excess Grout Using Sponge
This time, make sure there is no excess grout on the tile's surface or beyond the grout line. Rinse the sponge you are using in a bucket of water and change as needed as you clean off any excess. Then leave the grout to dry overnight.
Rinse immediately after you finish a section of tile, and wipe it down with a damp grout sponge. Remember to frequently clean the sponge and replace your rinsing water. Repeat the process until your entire floor is clean.
Here's the secret: magic erasers! I know there are grout pens out there that whiten grout, but that's just paint. I want to actually clean my grout. Magic erasers get the job done, and they do it quickly and relatively painlessly.
First, wash your tiles and grout with sugar soap using a toothbrush and scrubbing brush. We used Selley's Sugar Soap concentrate for this, mixed with warm water in a bucket – it works a treat. Use your toothbrush, scrubbing brush and some elbow grease to scrub the grout and give it a good going-over.
Two factors can produce this haze: efflorescence and sealer haze. Efflorescence appears as a white powder, normally on the grout. Sealer haze appears as a milky white haze where sealer has pooled and dried on the surface rather than penetrating the grout or stone. It is easily seen on dark-colored grout.
Grout almost always appears darker when wet than when dry. New grout can take 24 or even 48 hours before it's completely dry.
The first thing to try is to clean the tiles with a scouring pad and lukewarm water. If this does not work completely, use a mixture of 50% water and 50% vinegar. The acid dissolves the lime residues that make up a grout haze.
Grout needs to be sealed. It's naturally porous and will stain easily. Most installers of tile floors do not seal them because grout has to cure first.
You can run a dehumidifier, an air conditioner or an electric fan to help keep humidity levels low as the grout dries.
If grouted too early for instance of adhesive that takes 24 hrs to dry the white grout may discolour because of the moisture still in the adhesive and it cant get out due to the grout.. so will discolour... Small tiled area, there's nothing wrong with using rapid set and grouting the same day.
ANSWER. ANSWER - It is possible to grout over existing grout if there is enough depth to do so. 1/8 inch depth may or may not be adequate depending on the type of grout used. A latex modified grout may work, but you have to properly clean the existing grout to ensure the new grout adequately bonds.