Blotchy Grout [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-07-2007, 12:38 PM
First off I must say this is a fantastic website and all the pros input is to be commended.

I have recently tiled my 26 square foot bathroom floor with 6" tumbled Noce Travertine and all went well. I have just begun grouting (only the small area around where the toilet goes so far). The grouting went well I thought, but it is fairly blotchy this morning now that it has dried.

I am using Custom Products Haystack grout and at the suggestion of the Home Depot guy who runs the tiling seminars, mixed 2 to 1 ratio of sanded and non sanded. The grout lines are approximately 3/16.

Any suggestions as to what is causing this blotchy color effect? I have tried to keep water during cleanup to a minimum, but I am scared of the grout drying on the somewhat rough tiles. If I can figure out what I have done wrong before I continue the rest of the floor, the area around and under the toilet wont be that noticable.

Many thanks for any suggestions.

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03-07-2007, 01:56 PM
Hi Chris. If blotchy grout isn't the #1 problem we hear about, it certainly is amongst the top five.

Here's an article I'd like you to read on it.

My recommended next step is give it one more day to dry out. Then scratch through the surface in some inconspicuous area where the grout is lighter in color and tell us what you find. Is it darker below? If so then maybe a light washing and brushing with a mixture of 50:50 vinegar and water will clean up that lighter surface layer.


03-07-2007, 02:25 PM
Thanks for the quick reply Mike. I will do the scratch test you mentioned later this eveing. The majority is lighter, with the darker areas appearing to be mainly at the corner joints.

I did not follow the instruction for mixing the grout on the box since the sanded and unsanded grout call for very different amounts of water. I wonder if my issue has to do with mixing the grouts and if it might be wise to finish the rest of the job with purely sanded. This way I could follow the mixing directions rather than go be eye.

Thanks again,

03-07-2007, 02:30 PM
One other point I should bring up is that I cleaned the grout joint of thinset only where I thought it might result in the grout getting in smoothly. Some of the grout lines I left partially filled with thinset because it appeared that it would not interfere with the grout.

Is is possible that varying depths of grout lines could cause color variance/


03-07-2007, 03:08 PM
It's possible thin set in the joints contributed to the problem. But if the top half of the joint was clear then I'm guessing your problem is either water management or uneven drying due to other causes.

Too much water in the mix, during clean-up, or both can cause it. If you have a heat register in the room, plug it up. Hot air (or even cold air) blowing across fresh grout can cause you grief. Even sunlight coming in through a window will cause problems. Sometimes fresh grout is covered with kraft paper to manage these drying issues.

Then again too, if you had a lot of thin set near the surface this could prematurely draw moisture out from the grout, another cause of uneven drying.


03-07-2007, 03:30 PM
I went home at lunch and tried scratching the lighter areas a bit and no difference in color. Strangely, stratching the surface of the darker areas resulted in the color being lighter below.

I am going to try really cutting down on the water during cleanup on the next section as per the link you sent. I guess I will continue to mix the sanded and unsanded. since Ive gone this far.


PS There is no window in the bathroom and I closed off the ducting and plan on heating the room with a truecomfort underfloor heating system.

03-07-2007, 04:12 PM

plan on heating the room with a truecomfort underfloor heating system

Just don't try to dry the grout with the heating system.. :D

03-07-2007, 04:15 PM
I have actually not wired the heating system to the fuse box yet so I resist the temptation to turn it on without giving the grout a couple of weeks to fully cure. I really would like to see how well it heats the room though.


03-07-2007, 10:08 PM
Speaking of the radiant heating, how long should I wait for the grout to cure before using it?

I used Megalite thinset and the Polyblend grout.


03-08-2007, 06:24 PM
I'd give it 2 weeks...

03-08-2007, 07:08 PM
Thanks again for the help. My second go at the grouting is far better. I made every effort to use the float to remove excess grout from the tiles and then resisted the clean process a little longer to allow the joints to firm up more. I then used barely wet sponges to clean up the remaining grout on the tiles.

It appears my problem was too much water at cleanup. Thanks again to Mike for the great link. It was the best of all the many I have read on grouting in the past few weeks.


10-06-2009, 05:40 AM
Good morning gentlemen. I come to you today with a grouting problem.

I just finished grouting my 200sqft kitchen. Lowes sanded grout with the admixture was used, 1/4 spacing. Gray thinset, dark tan grout. Ceramic tile.

I read many posts on this form about grouting and had a good idea what I had to do.

After properly mixing the grout with a slow speed drill I applied it. Floating it in the joints and raking off. The tiles have a recess so after about 10 minutes I raked the joint to achieve proper joint height. Then I began the sponging process. There was obviously more material left on the tile than I would like but I used the scrubber side of the sponge 1st at a diagonal and after subsequent wrings I had what would say was a clean floor. My last and fatal sponge move was raking it across the joint to remove that little bit of water that came from the spongings. This smoothed over the top of the joint.

So now I have blotchy grout and I don't know where to go from here and I must admit, I'm a bit nervous.

I have not given it the scratch test as mentioned above. What are my options here to achieve. Can I scrub the grout with a wire brush to scuff the upper glazed over surface?

Thanks in advance for the advice :/

10-06-2009, 08:59 AM
I hope your grout color evens out. A few years ago I tiled a floor and the grout dried all blotchy, I was at my wits end, about to tear it up and start over. I ended up painting the grout. It was tedious, but in the long run better than tearing it out and starting over.

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10-06-2009, 10:46 AM
paint the grout! i dont even want to entertain that option!!

so any other suggestions before i reach my wits end?

(thats for the good luck BTW, i think im going to need it)

10-07-2009, 07:46 AM
So right now I am entertaining a few options

1- scratch test, if darker color is underneath what I messed up above, can I use a stainless steel wire brush to rough up the top layer exposing the layer underneath?
2- Use a grout rejuvenator? (can anyone give advice on that) not too familiar
3- Wait 10 days and use a Sulfamic acid with a nylon brush
4- I know they make colored grout rejuvenator (?) but I really wanted to bring up the intended grout color.
5- Whats this I hear about vinegar and a brush?
6- RUN!!!

Your advise and opinions are very welcome as tonight im trying the scratch test with the wire brush 1st.

Should I wait 10 days before using any kinda of liquid (aside from the acid) i.e. vinegar or I read somewhere about baking soda…

Thanks in advance.

10-13-2009, 11:36 PM
I had the same problem in my bathroom tile job. I used Aquamix grout colorant. That was about 3 years ago. Still looks good. I tried everything before I used the colorant.