Patchy Grout problem

[dangerSteve]

Hey guys,

On a job at the moment where another tiler has just finished the kitchen floor, 600x600 white polished porcelain on Gypsum screed. Anyway, he finished grouting over the weekend and come Monday the grout looks patchy all over, a bit like army camo effect, as though its still wet in places. The grout used was Mapei Ultracolour Plus in a light grey, a Washboy was used to mop-up.

Any ideas what could be causing this?? I have had jobs in the past myself where the very same grout has looked patchy but you didn't really notice against darker tiles, the white tile is obviously highlighting the variation and making it look really bad.

Steve.

[Dave]

Hi steve have a read of THIS i think it might help you out...

[dangerSteve]

Thanks Dave but i know its not efflorescence, its dark patches in the grout, as though its not dried out properly, the opposite to this.

We have been using impregnator on the tiles to seal them I'm wondering if this has reacted with the grout?? Other than that I'm clueless on this one.

[Dave]

Silly question but screed was fully dry ..?..

And how long was the grout left before sealing tiles..?..

[dangerSteve]

Screed has been dry for months, its an empty house that the customer has been working on for over a year now.

Tiles were sealed before grouting, they haven't been sealed again yet due to this problem.

[Dave]

Cheers steve..just eliminating options here....Is there any heating on in the house..lower temps can alter drying times of the grout...But after 3 or 4 days steve it should be dry..

Have you called Mapei tech line...?

[deanotile]

I don’t know if you will get me but I think I know what the problem is. If the grout in the joint was a little lower in parts and the wash boy sponge was a bit dry you end up cleaning the grout of the face of the tile but not smoothing the joint as much in the parts where the grout is darker.

[MrSpoon]

is it rouh patching to the touch? could be that hes decided hes not happy with a few hollow bits and decided to smooth it over after hes finished grouting and disturbed the top surface of the grout, i say this as im sure i did the same thing when i first started!

[Sir Ramic]

I asssume all joints were clean before grouting and grout was properly mixed ?

[dangerSteve]

No probs Dave, there is underfloor heating but its not functioning yet, I think they only had it on a couple of times to test it, but this was months ago. It has been chilly lately but as you say after 3 days its should have dried out.

Makes sense Dean, you might be onto something, best way would be to try and recreate this on a sample panel and see if it does the same trick.

[dangerSteve]

is it rouh patching to the touch? could be that hes decided hes not happy with a few hollow bits and decided to smooth it over after hes finished grouting and disturbed the top surface of the grout, i say this as im sure i did the same thing when i first started!

Maybe yeah I haven't actually been and felt it, how long after grouting can this occur? I have myself smoothed rough areas or where I've filled an air bubble, but this is usually as part of my sponging off process about 5/10 mins after grouting.

Joints were clean and the grout mixed using paddle mixer, he does mix it a bit runny though.

[Sully]

Steve,

I use a lot of Mapei Ultra Colour Plus and while the results are 'worth the pain', it's a tempermental product to work with. I would think of two things that could have happenned here or maybe a combination of both.

The volume of water in the grout mix must be followed as per their instructions - think it's 1.1 - 1.3 litres per 5kgs. Too much and the mix is too wet resulting in patchy grout - and other problems including grout failure. Secondly, too much water in the washdown - a overly wet washboy or just too much water pushed around the floor. Again, it may be a combination of the two.

I'd wage a blind bet on this being the issue

Solution: Grout colourant would be my choice

Andrew

Andrew

[MrSpoon]

Maybe yeah I haven't actually been and felt it, how long after grouting can this occur? I have myself smoothed rough areas or where I've filled an air bubble, but this is usually as part of my sponging off process about 5/10 mins after grouting.

Joints were clean and the grout mixed using paddle mixer, he does mix it a bit runny though.

during the washing off stage after 5/10 minutes, come to think of it it could well have been down to too much water while washing off as spend alot more time making sure i get asmuch water out of the spondge before wiping and the problem seems to have gone

[dangerSteve]

Cheers Andrew, I think you could be spot on mate!! When he phoned Mapei I think they mentioned something about too much water content in the mix. To be truthful its something I have never really bothered about myself, the water mixture amount on the bag I mean. I never like to mix a whole bag in one go because theres either too much grout to spread or because the room doesn't require a full bag. I might sound thick here but how do you manage this? Does it require you to start measuring out grout? Surely it doesn't have to be that accurate?

[whitebeam]

With mapei it does, A lab rat told me it's very high tech. Measuring jugs at the ready

[Dave]

Steve..if you read that link i put up it dose mention about amount of water in the mix..

[P'boro tiler]

ive bn on a mapei product training day and basically its all about using a good measuring jug! aparently measuring buckets arnt accurate enough for mapei grout. mine always smash to bits anyway!

[dangerSteve]

Aye... Well i think were agreed its pretty much the fact he's probably mixed it like **** and then for good measure not wringed out the washboy enough while removing the grout.

Solutions : Grout Colourant? We talkin about the grout pens?

Could he not scrape a couple of mil off the grout from the joints then mix up another batch and apply this ontop? Or is this a big no no?

[Sully]

Solutions : Grout Colourant? We talkin about the grout pens?

Could he not scrape a couple of mil off the grout from the joints then mix up another batch and apply this ontop? Or is this a big no no?[/quote]


Am I allowed to mention the brand on here? It would be Aquamix Grout Colourant for me but you will have to settle for the closest match. As for raking out the grout , rather him then me but might be a good way for him to learn from his mistakes . I would be raking it all out though and not depending on a 2mm 'surface bond' which might be weak.

Andrew

[MICK the Tiler]

Far too much water, see it all the time and with porcelain the edge of the tile is porous so some of the fines in the grout end up sucking into the edge of the porcelain leaving the grout streaky. You could try an intensifier on the grout, failing that you could try a little hydrochloric acid mixed 4:1 with water make sure the porcelain has been sealed first then using a nail brush scrub the loint with acid mix, neatralize with Bi-carb soda mixed with water then allow dry. Always do a small test area first before you get too full on with acid. Failing that it will need to come out and be re-applied using less water in the grout allow the grout to really firm up in the joint the cut back with an almost dry sponge.

[groucho]

Funny that . I was going to post a thread about this. everytime i use a cement grey grout there is always a few patches that i get. I never get this problem in any other colour grout. I agree its too much water. Ive tried all sorts. Leaving the grout as long as poss to set then just a quick wash down tiles. but whatever way theres always a patch somewhere.

[TilingLogistics]

Quite often an intensifier will work. Do a test patch with Aqua Mix Enrich & Seal then if it doesn't work go down one of the harder routes either a grout colourant or re grout. A word of warning Aqua Mix Grout colourant will highlight every imperfection in the current grout so bear that in mind if you go the recolour route

Kev

[chrisroe]

Mapei grouts are the best imho but can be a pig to use

medium grey always seems to be very plasticy

beige 2000 prone to efforecence

the white is flippin green not white

other than that

its a brilliant product and if you stick with it then you will win future work ia recommendations

[macten]

Using the beige 2000 now - dired a little patchy for me but luckily the effect looks good cos it really matches the tiles. Says on the pack that it contains anti - eff, doesn't seem to work though!
Will try the tips next time though.

[trisha flood]

hi
we have just had our kitchen tiled and our grey grout is patchy. we bought a very small tin of water based grey emulsion from b&q and painted it on with a very small brush. It now looks fabulous.
Ill get the name of the paint if that will help

[doug boardley]

thanks for that Trisha, I'm assuming OP got sorted as this thread is now 3 years old...

[Dave]

Emulsion ok lol