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Beth P 10-14-2011 09:46 PM

Grout Discolouration
4 Attachment(s)
Hi Everyone,

We recently grouted brand new tile on bath/shower surround walls. We used Mapei Keracolour U and followed all the directions with regards to dry-mixing, using multiple buckets of water when washing, and washing the tiles before grouting. We are still getting tile discolouration. I am not sure if it's efflorescence or not. On Mapei's site, they said to dampen the areas of grout that look whitish and then scrub with a nylon brush to get rid of efflorescence. Well, no dice.

When I rub my finger along the lightened areas, I do get a bit of fine powder remaining on my finger. When I dampened the grout, the lighter areas remained lighter even when wet. The lightness is spotty around the whole tub surround. We did use tap water to mix the grout.

Behind the tile we used a 6mm poly vapour barrier sealed to the tub with the tar-like substance we were told to use. We then used 1/2" hardibacker board, attached with the correct water-resistant screws. We used a thin-set mortar directly on the hardibacker to attach the tiles. The tiles sat for 24 hours before we grouted.

I've attached a few photos, hopefully they help.

Any help? Is this efflorescence? How can I remove it? If not, is there something wrong with the grout or did it just not mix right? Can I use a grout colourant? If I do use a grout colourant, will it actually make all the grout the same colour or will the light areas still stay lighter?

Any help would be greatly appreciated as Mapei's technical support wasn't very helpful.


JazMan 10-15-2011 09:27 AM

Hi Beth,

Sorry you're having this problem. What's the size of those tiles? How wide are the joints? From here the tiles appear to be 12" or larger and at least some of the joints look over 1/4", the last one especially.

If so, why use Keracolor U?


Bud Cline 10-15-2011 12:42 PM

Efflorescence is a word that gets thrown around these DIY websites like it was a beach ball. Efflorescence is a neat word that everyone likes to say and a lot of people like to think they have been stricken by it. Some people can even spell it correctly some of the time. Efflorescence in tile work is rare but the word itself sounds so exotic that people like to think they have it. It's kind of like: "Oh wow I have a slight fever and head ache and my joints are aching I must have; MALARIA."

Use clean water, mix in a little white vinegar and scrub the tile. If that doesn't rid you of the disease then go buy some "Grout Haze Remover" because that's all the problem is: Grout Haze.:yes:

Beth P 10-15-2011 12:43 PM

Hi JazMan,

The last picture is a close-up. The tiles are 13"x13" with 1/8" joints. We used spacers so they'll be within +/- 1/16" of 1/8".

As an update, I did "wash" one wall by wetting it with distilled water and then scrubbing with a nylon brush. Although it still has lighter/darker colouring, some of the splotchiness seems to be gone. By "splotchiness" I'm trying to describe the almost scale like appearance that you can see in the last photo.

We're really concerned about this because we need to grout our counter top next, and we don't want it to turn out like this! Any help you could provide would be much appreciated!

Beth P 10-15-2011 01:23 PM

Hi Bud, thanks for the response. Is it still grout haze if there's no residue on the tile, but just on the grout?

Bud Cline 10-15-2011 01:32 PM

Okay now I'm lost.:) Can't see anything in the photos to complain about to begin with, with the exception of possibly some grout remaining in small pockets in the tile's surface but I'm not really sure what I'm seeing there. In addition I think I see some sponge marks in the surface of the grout from a less than attentive cleaning process maybe.:)

I guess I don't know what the problem is....:no:

Beth P 10-15-2011 02:02 PM

The lighter spots on the tiles is just the pattern on them. On the last photo, if you look at the grout lines, you can see lighter and darker areas, almost like a scale on it. It's a bit hard to tell from the pictures - it's pretty hard to get a good close-up shot without whiting the whole thing out with the flash, but that's what's bothering me. Is that what you're thinking is sponge marks? When I rub my finger along the area with the whitish scale, I get small amounts of dust left on my finger.

Bud Cline 10-15-2011 02:13 PM

Beth your problem may be (is) you basically used the wrong grout in my opinion. Unsanded grout is for small grout joints up to 1/8". In my thinking 1/8" is pushing it. Unmodified grout will shrink terribly and sometimes crack when used in a joint that is too wide. The next problem is the grout has no bulk (sand) so as you continue to drag a sponge over the grout surface you continue to pull grout pigment from within the (too wide) grout line. At some point this will stop and you will be able to clean the grout. If what I am seeing in the surface of the grout is streaks and not ridges...that's a good thing. Try some white vinegar. If that doesn't clean it up use some grout haze remover.:)

To tell you the truth...sealer may also do the trick for you.:)

Beth P 10-27-2011 05:30 PM

Thanks for the help everyone. We got the grout to be fairly uniform in colour (still too light - argh!) and it's now sealed and we're well on our way to being done!

Bud Cline 10-27-2011 08:22 PM

So...are you going to tell us what it is you have done or is it now a secret?:)

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