Once the grout has hardened, the tiles will be left with a slight haze on them. Clean it up by going over the area lightly with a damp cloth, then buff immediately with a dry cloth.
Yes new grout can be installed on old grout. Make sure the old grout is thoroughly cleaned and then wet before installation. I do this all the time. There is absolutely no need to start over and given the quality of the install you have had so far I would say that starting over might introduce more issues.
Per ANSI 108.10, the joints should be “uniformly finished. Cushion edge tile shall be finished evenly to the depth of the cushion.” This means that grout joints should be uniform in color, smooth, and without pinholes or voids. The voids or pinholes can be filled and re-tooled with a sponge.
Porous grouts attract water, dirt, oils, etc. While the tile industry does not require sealing, it is always recommended, especially in wet or high-traffic areas. Penetrating sealers are the most commonly used and offer high water, chemical and stain resistance.
Optimally, no more than 30 minutes should pass for the initial wiping off of excess grout. This process must be performed gently with a wet grout sponge during regrouting. Once the grout application is complete and excess grout removed, there will be a second waiting process.
It is generally better to use brushed grout sealer than spray sealer as you can apply more sealer with more control.
Once you've activated the micro-scrubbers inside, your Magic Eraser is good to go. Start by swiping it firmly across the desired surface. In just a few swipes, you should start to see grout messes and buildup begin to disappear!
We recommend waiting for at least 48 hours after installing a grout before you apply a sealer. Older grout should be cleaned thoroughly before being left to dry. Make sure to protect grout from spills and stains during this time, otherwise you'll be sealing in the dirt instead of keeping it out!
Steam cleaning is one of the most powerful ways to clean grout without the use of harsh chemicals. Professionals often use steam to loosen the dirt and other particles trapped in the grout without needing to scrub manually.
Choosing the correct grout is a basic step in the process of regrouting over existing grout. The most common grout types are cementitious (which is unsanded or sanded) or epoxy (which is also sanded or unsanded).
You can apply new grout right over the top of the old grout. To do this, all you need is a grout removal tool. Use the tool to strike out the old grout, making sure the depth is at least 2mm, which is about the thickness of two dimes stacked one on top of the other.
If you run into problems like your new grout not adhering well to the old grout, you may see your new grout chipping or cracking within just a few months. For the best longevity, it's recommended to remove old grout before applying new grout.
If cleaning is not possible after 24 hours, then you should not leave your grout haze uncleaned for more than 10 days, otherwise, it will be even harder to remove. Finally, you need to be sure you have the right cleaner for your tile material. Acidic cleaners, for example, should not be used on stone.
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.
Grout Must Set and Cure
Then the grout needs to be cured for a couple of days. 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.
Whoever installed your floors most likely did not seal the grout because it needs time to harden and cure completely.
It is important not to leave any excess sealer on the tile surface because it won't get absorbed and it can leave a sticky surface that can become a maintenance problem.
If the grout remains on the surface of the tile for more than 30 minutes, it is much more likely to result in grout haze. In some cases, grout haze may form after a few days.
Premixed flexible grouts are ready-to-use products that don't require any additional mixing. They're made with either acrylic or urethane resins and offer excellent flexibility and water resistance. These grouts are ideal for DIY projects as they're easy to apply and clean up as you go.
Mistakes such as using the wrong grout, uneven application, and using too much water can yield an end product that won't last long (and looks unsightly, too).