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.
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.
Once all the joints between the tiles are grouted (working in small areas), allow approx. 15 minutes for the grout to touch dry (at 20°C). Using a dampened sponge (not wet), clean the surface diagonally to the grout lines. Rinse out the sponge frequently with clean water.
Floor grout, in general, usually dries completely after 24 hours, although humidity and other factors can extend this drying time to 48+ hours. Grout haze can sometimes be simply buffed out with a dry towel or cheesecloth, if done immediately within the first 48 hours.
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.
As go-to grout and tile care specialists, The Grout Medic truly wants what is best for your tile. Waiting too long to wipe grout could result in unsightly grout haze. Don't wait too long to wipe off grout!
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.
There is no reason not to wait to apply grout, unless you have used a quick-set tile adhesive. The thin-set mortar needs time and air to properly set and cure for strong bonding. Improper curing can lead to a flaky adhesive, which will cause loose or failing tiles and bonds.
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.
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.
That is another very important clue. Grout almost always appears darker when wet than when dry. 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.
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.
Dampen the substrate and tiles
The use of water is an important part of the entire installation process. Before grouting, use a clean sponge with potable water to dampen the substrate throughout the tile installation. Next, dampen the edges of the tiles with a light water spray bottle.
But if you are using 2mm or 3mm tile spacers and don't have a grouting tool to hand you can use the top of a round pencil to get the uniform finish. Leave in water to moisten and dip each time you use the pencil.
Grout prevents shifting, not just acting as a buffer between the tiles but holding those tiles firmly in place and preventing movement in the first place. Grout is a very important part of your tile floor or backsplash.
Grout that hasn't dried properly or gets wet before it cures may also allow water to seep into the gaps and behind tiles. Plus, if grout isn't given sufficient time to cure before sealing it, it may flake or peel.
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.
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.
But once the job is finished, there is a curing process to follow. The curation generally occurs in about twenty minutes; however, the tiles should not be walked on for a solid 24-hour time frame to allow them to set fully. It is a crucial period that will ensure the beauty and endurance of the materials.
You will need to wait another two to three days for the grout sealant to cure. Then, you can finally jump in and take your shower!
So yeah, we're really glad we decided to do the haze remover. Although it was a bit tedious to apply over the whole wall (you basically apply it with a sponge, let it sit for a few minutes, then rinse and dry it off). But it was actually good practice for the next step: sealing.
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.