If some grout joints are deeper than others, the grout will cure unevenly with resulting differences in color. Making sure that your grout joints are satisfactory depth will help prevent this problem. The practice of sweeping in the joints before grouting can cause uneven curing.
Inconsistent grout color is a condition where colored grout dries to its expected color in some areas, a darker color in some areas and varying shades in-between. The main cause for this variation in color is uneven drying of the Portland cement in the grout.
Grout almost always appears darker when wet than when dry. New grout can take 24 or even 48 hours before it dries completely.
Generally, a flush joint is desired on any square edged tile (including rectified tile), but the ANSI standard found in A108. 10 section 5.3. 4 states, “All grout joints shall be uniformly finished.
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.
Grout turning white is usually due to efflorescence, which the movement of salt or minerals to the surface of porous material (such as your grout) and forms a whitish coating.
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.
SHOULD GROUT BE DARKER OR LIGHTER THAN THE TILE? This is somewhat a matter of taste, but if you have a variegated tile with several shades, you have several options to choose from for grout color. Choosing lighter colors blends your design together. Darker colors create a more dramatic effect.
The color from the same bucket of grout can look different if on a wall or a floor in the same area such as a shower. The color can change based on the lighting/shadows. The color will change when the surface is wet because different grouts have varying water absorption rates.
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.
If your old grout is cement based, re-grouting might be necessary, especially if the grout was not sealed properly at the time of installation. Cement grout is porous and prone to absorbing moisture and dirt that can cause it to break down and deteriorate faster than other types of grout.
However, you must make sure you are re-grouting with the same type of grout you originally used. If not, the second layer will not adhere well to the first and you will have to do the same job over again in a few months' time.
No matter how good you are with a sponge, once everything is dry (usually overnight) there will still be a grout haze on the floor. You'll be tempted to use a wet cloth to wipe it off, but that will put you in a vicious grout-wiping cycle. A better idea is to use a dry towel to rub off any haze.
It is important to wait until the grout has set in before wiping the tiles clean, as premature wiping can result in gouges. However, don't wait too long, or the grout will dry onto the tiles, potentially causing irreversible damage.
Add too much water as you mix and the grout will never get as hard as will grout mixed properly. The proper consistency for grout, in fact, is like that of a thick cake batter. The grout, once mixed, should readily stick to the end of a putty knife.
Grey Grout
Softer than a dark grout but much more user-friendly than a white grout, grey is the perfect solution for a kitchen splashback as it will keep looking cleaner for longer. Large white tiles often look better with a grey grout as it will frame the tile.
The consistency of grout should resemble smooth peanut butter. It should be malleable but not dripping from the trowel when lifted. If the mix is too stiff or dry powder is visible, add more water.
A good grouting job can often mask imperfections in a tile installation, while a poor job can mar an otherwise outstanding tile installation. To look good, the grout must be smoothed so it forms an even border around each tile.
Yes, eventually grout haze goes away but you need to take special measures. Just by diligently wiping down the surface with a wet sponge, the haze will remain and won't come off. Will Vinegar Remove Grout Haze? Yes, vinegar remove grout haze.