Expert Answers
Why hasn't my grout harden?
QUESTION
My bathroom marble floor has been grouted twice now and has not hardened. I have a water softener. Would that make a difference?ANSWER
ANSWER - If you are using a cementitious grout it should harden. If you used too much water in mixing the grout and/or too much water in cleaning the grout during the installation of the grout you can weaken the grout causing it not to harden.In some cases if the grout dried too fast it may not have been able to fully hydrate, so if you wet the grout again it can then continue to harden.
I have never heard of water softener water affecting grouting.
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We are using Mapei kerapoxy grout in a new DIY finishing ( general contractor did most of the new build) of a tiled shower and bathroom floor. Once we open the 1 gallon container, are we battling the clock, or can we reseal the container for a short time, say a day or two? Thanks!
Kerapoxy is a two part epoxy. Once you open and mix them together you need to use it all and relatively soon. It is possible to mix a portion of the units, but the ratios has to be perfect or it won’t set up. Read the product data sheet for details.
Hello–we have Mapei Ultracolor Plus FA grout installed by a contractor in our shower, bathroom, and backsplash that has dried soft and powdery and gets softer when wet. Is it possible to harden this type of grout using a sealant? If not, does it need to be removed and replaced?
Normally a grout dries soft either because it dried too soon before it fully hydrated. If this is the case, normally if you wet tile grout for 24 hours or so it will harden.
Sometimes the grout won’t get hard because either they used too much water in mixing the grout or too much water cleaning the grout during the installation process. There are clear liquids like liquid glass or other products that manufacturers recommend that can possibly harden the grout. Contact Mapei and ask them what they recommend.
We are also having a problem with a lot of powdery grout in a kitchen backsplash installed about 5 weeks ago (2×6” glazed ceramic tiled was used for the backsplash). The contractor used Mapei Ultracolor Plus FA grout. The powdery grout is not everywhere but it is in several grout joints and if we run our fingers over the grout we get a fair amount of powder on our fingers and the counter. We are wondering how
this might
have happened and what to do about it. We have also
applied 2 coats of Miracle 511 H20 plus sealer and didn’t notice the powdery grout until
after sealing. Mapei has told us to strip
the sealer and then
try their Grout Refresh or their Ultra Care Grout Sealer – would one of these products stop the grout from being powdery (rust-oleum who makes Miracle has told me that their sealer can’t be stripped bc it is a penetrating sealer and they
do not make a product that strips sealer so additional question – how do we remove a penetrating sealer like the Miracle 511 H20 plus?). Mapei told me to contact rust oleum about what to use to strip the sealer. I also was told if Grout Refresh or the Mapei Ultracare sealer don’t work then the grout needs to come out. Do you have any suggestions for us?
As stated in the above answers, there are a lot of potential reasons why a grout might not get hard. There is a chance that the grout itself has some deficiencies that make it problematic. It can be the installer who used too much water in mixing the grout and/or used too much water cleaning the grout during the grout installation process. If the grout dries too fast then the grout can’t fully hydrate and that can keep the grout from getting hard. Regardless of what caused the problem it shouldn’t happen. Cementitious grout should get hard.
Unfortunately as a homeowner you get stuck in the middle because everyone points the finger at someone else. Your installer installed the grout so he is the one how needs to take the lead to resolve the problem.
Cementitious out manufacturers are use to getting complaints whether it is their fault or not, so they suggest a liquid that penetrates into the grout and hopefully makes it hard enough. Sometimes it works sometimes it doesn’t. The penetrating sealer does penetrate to some degree into the grout, but it tends to wear off. If you put a drop of water on the grout and the water beads up tightly and it doesn’t leave a wet spot on the grout then the sealer is working. If it leaves a wet spot then it is absorbing to some degree.
Thank you for your reply to my original message. After living with powdery and crumbling grout for several months, we decided to find someone to remove our kitchen backsplash grout and re do it. It looks great but unfortunately I am still getting some powder when I rub my finger across the grout joints. While it doesn’t seem to be crumbling onto the counter as our previous grout did ( and we have about 1 more week to go until it is fully cured). I’m assuming that there should be no powder on my fingers? Also the new tile guy removed about half of the original failing grout (Mapei Ultracolor plus FA) but it looked like a lot less to me particularly in the vertical joints. I’m wondering if that could be part of our continuing problem? He also switched to Mapei Keracolor U (we have 1/8th inch joints) mixed with Mapei grout stabilizer instead of water. Could putting this grout mix over the Ultracolor plus be part of the problem or could it be a mixing issue
(or both?). I’m also now wondering about the water absorbency of our tiles. They are a glazed ceramic tile made in Spain with a water absorbency rating of >10%. We live in Denver where it’s quite dry but I’m wondering if the absorbency of the tile could also play a role in the hardening of the grout? In summary, we are going to ask the tiler to come back and take a look. If we end up regrouting again I’m wondering what might have gone wrong and what he could do differently? Thank you.
the powdery material is efflorescence which are minerals in the underlying ground and concrete that is transferred to the grout surface through evaporation where the minerals are precipitated on the grout surface leaving a whitish substance. As long as there is moisture to absorb minerals and moisture to transport it to the surface to evaporate you will likely get efflorescence.
Porous tiles can cause the grout to dry to quickly and not fully hydrate.
You could consider cutting out all the grout and replacing it with an epoxy grout that is impervious.
Can you tell us how to tell the difference between efflorescence and grout powder? Our grout happens to be white so that doesn’t help. What is appearing on my fingers when I rub them across a grout joint looks and feels powdery and chalky. I had assumed that it was grout powder. Would the remedies be different if the grout is powdery and soft versus the problem being efflorescence? Also would a kitchen backsplash be a common place to have an issue with efflorescence? We have not had moisture issues in our kitchen. If our grout possibly dried too quickly I believe that I had read that you had recommended wetting the grout? Not sure if we should try this? Also, we are going to seal the grout to slow (or maybe even stop) the powder. Do you have a sealer recommendation to help with our grout problem (and a product that would work well with the keracolor U plus the grout maximizer)? We would like a strong sealer that will do a good job protecting the grout as well as preventing oil and other food stains in the grout as some of the backsplash is right behind our cooktop. We would prefer a water based product over solvent based but am not sure if the water based products are as effective? Last, if we decide to remove the grout again but don’t want to use epoxy grout, would a premixed grout such as the Mapei Flexcolor CQ or another brand be a suitable option considering all of the issues that we have had? If we were to decide to regrout again it seemed that you were suggesting that most of the grout would need to be removed? Would this only be required with epoxy grout or for any grout including the premixed variety? Thank you again for your assistance and for being an excellent resource!
regarding your last questions below:
If you scrape up some of the calcium efflorescence powder and drop it into a cap full of vinegar it will effervesce. If it doesn’t then it isn’t a calcium efflorescence.
Treating the symptom of the problem, removing the efflorescence, doesn’t fix the problem. You have to fix the problem that is causing the symptom or it will reoccur.
You have to research with the various grout manufacturers to determine what grout you want to use. We do not provide that information.
HELP! Our tilers used the incorrect coloured Mapei kerapoxy grout on areas of our new bathroom walls including in the shower area with waterproofing behind. Small 200x100mm ceramic tiles laid in a brick pattern, with walls 2.8m high. How can we safely take off the top layer of grout so we can put the correct colour on top without damaging the tiles?
Re the comment above – tile spacing is only 2mm
With a 2mm wide grout joint that is very narrow and it will be particularly hard to remove considering you are using an epoxy grout without chipping the tile edge. Normally you need at least 1/8″ depth to apply grout over grout, and then the underlying color of grout can affect the color of the new grout.
There are Grout Colorants that match most grout colors that is basically an epoxy paint. In theory you can paint over the existing grout and change it to any other grout color. It is a very tedious process to paint the grout joint and to keep them looking straight.
You might be able to get a heat-gun and heat the grout in the tile joints until it is soft and then take a utility knife and see if you can scape it out of the grout joint. Again, it can be tedious and messy to do this, and you still could chip the edges of tiles.
Thanks you! It sounds like a bit of a nightmare. Is the paint finish hard wearing? What products are there? If we use a heat gun what temperature-ish will soften the epoxy? Is it likely to damage the waterproofing layer behind the tiles? If you use a heat gun does that mean the epoxy left behind is structurally/waterproof wise unsound? Are you relying on the layer you put over the top? Our current thought is to heat the grout and remove some of it with a hard plastic tool so as not to damage the tiles but I guess the softening temp of epoxy would need to be less than the melting point of the plastic.. which might be tricky?
If you don’t have the experience with these materials then you should not try to do it yourself because there are too many variables to consider. You need to hire a qualified professional who understands how to work with these products and who can determine how deal with the potential situations that can occur. Regardless of what you do, be sure to always test an out of the way small area first and make sure it meets your satisfaction before applying it to the entire area.