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Our bathroom has been completely refurbished including the laying of 33 square metres of wall and floor tiles. While the general standard of the work is good the grout on two walls has not dried to an even colour and in some large areas it is noticeably darker than that on the other walls and the floor. We have left it for over two weeks but the problem is still evident. The bathroom fitters say that they have no idea what has caused the discolouration and have not as yet suggested a solution.

Grateful for suggestions.

I would suggest it is batch variation. I am always careful to measure the same amount of powder with water for each mix. If you have to use two separate powder packs then there is always a chance of batch variation. I do not know any method to sort this out, the pro's might have some tips, but to me it sounds like a job for the Bosch PMF180 to hack the grout out and start over.

DWD

Many thanks for your response. The difference is very noticeable - using this grout colour chart at
http://tilecouture.co.uk/pages/Ardex_Fl ... =62814.cfm
as an example, the colour variation is from 04 Spring jasmine (the required colour) to large areas of several square metres matching 08 Floating driftwood and some small areas as dark as 23 Stormy mist. I wonder if batch differences would account for variations as noticeable as this?

No, it should not. I suspect that the powder mix was not given a good stir/shake to ensure the pigment was at an even level through the bag. If the bag was simply opened and scooped from the top then this might cause the variation. I am not an expert on this but I think coloured grout mix is a mixture of of cement based products and colour agents. If this colour bonds onto the cement particles then the mix is even if they are individual particles that come together when mixed with water then you would see the chance of there being a variation. My speculation might be a load of pants but it would give you one explanation. So, is it product failure or the operative not taking enough care? Have a chat with Ardex and seek their view.

I do not know how you can overcome this simply and if you can prove the bath fitters are at afault they wil have to rake it out and redo it in my opinion.

Have a look at this video which shows grout removal http://www.ultimatehandyman.org/video/t ... emoval.php

Let us know how you get on.

DWD

Interesting. When you say 'rake it out' does it all need to be removed or just the surface layer?

I would say enough to allow a good cover of new grout. As you can see with the vibrating action of the Bosch tool in the vid it does a fair job of removing grout lines.

As I said earlier, I think it is worth contacting Ardex and seeking advice on the problem.

DWD

It could have be a number of things, such as not being mixed correctly or what is often the case, the grout has been washed too soon and with too much water.

By that I mean at the time of install not you washing it

Oh the grout can be recoloured with Fuga Fresca to correct the different shading

http://www.mapei.com/GB-EN/product-deta ... &IDLinea=1

sounds like the grout has been either over-watered or washed down too soon.

Contact your supplier and get them to send a rep from Ardex out to inspect it.

We've recently had a few people do this with us, and each time it's been down to installation problems.

Cheers

I had a chat with the grout manufacturer's tech people today and they asked me to scrape the surface of a small section of the discoloured grout which revealed a much lighter surface. Given this they are certain that it is the cement base brought to the surface by too much wetting too soon after the grout was applied ie not sufficient time was allowed by the tilers from grout application to their initial (and perhaps over enthusiastic) cleaning.

They suggest that the tilers should try a 1:1 solution of Lithofin cement residue remover. In the event that this does not produce an entirely satisfactory result they recommend the use of a polymeric grout paint (such as the Mapei product suggested by Colour Republic).

Many thanks for the very helpful responses.

I can't see the lithofin saving this. I'd personally get a raking tool and re-do it.

Lithofin cement res. remover is best used for clean up jobs, such as grout film on tiles etc.

Have you contacted lithofin's support team? They're their pretty much all the time just to answer any techy questions you may have.

Cheers