grey discoloration on tiles after dark grouting

[tradey]

Dear all experts,
Me and my dad has put a LOT of effort into tiling a kitchen wall, and all was going swimmingly until the grouting: while sponging down the wall after grouting with antracite grey (rather dark graphite-like grey) some tiles showed flamy grey discolouration (see pictures). Grout was applied according to instructions (my dad has done this several times) and did not stay long before sponging off. The discolouration shows mainly on the corners of tiles, some worse than others, save for a thin strip by the edge where the glazing possibly is thicker. Can water get in from the front of a tile and through the pores if glazing is poor? Worst case scenario is, I suppose, that the pigment in the dark grouting has travelled with moist into the biscuit layer somehow through the glazing?! Could that really be the case? If so, is patience and a generous drying-out the best cure here?



I have browsed so many forums and am not sure what I find matches my problem. Some say vinegar, others say acidic products, I tried a few things but it is just too obvious that the discolouration is somehow "behind" the glazed membrane. Some might refer to this problem as ingression, and I have noticed the term "bruising" here and there on forums - does this apply to my kitchen tiles? As the pictures show, some tiles seem unaffected, but 40% of the mounted tiles show discolouring of various degrees.

We are so sad to see the result and desperate to find a solution other than tearing it all down and starting over again. Did we get a poor batch of an already poor product? I am embarrassed to say that we did buy the cheapest standard white tiles which were not particularly thick and has no glazing on the edges. That I will never do again, so help me the DIY god, if there is one. Immensely greatful for all advice from experienced tilers, wherever you are. Will the grey stains ever go away? Please help.

 

[Time's Ran Out]

I think that you have hit the nail on the head - a poor quality glaze, that has accepted the dark grout into the pores and stained the biscuit. I don't think that there is any remedy in the cleaning stakes as the grout will have gone in the side of the tile as well.
Unfortunately darker grouts do have warning instructions specifically for this and a test area is always advised (too late here:mad2

We had 1 case of marking the back biscuit of white tiles with a felt tip pen no's 1-5 and the discolouration came through from the
adhesive as it soaked into the tile and stained the front glaze from behind - you could see the no's.

:welcome:.

 

[tradey]

Thank you for a swift reply, and for welcoming me in the forum! Slightly discouraging as I understand my worst case scenario just might have happened. We used Casco antracite grout - I looked at the packaging and there were NO warnings or advice on testing printed on the box. I had no idea that tiles would behave like this, as if they were not sealed at all. Of all desperate solutions going through my head, one is to get white car paint and just spray on. Dear god.

 

[jay]

:welcome: good advice there by timeless , cheap tiles if you have trouble cleaning the grout off think about grease and germs ,might be best to remove and redo

 

[nybor62]

welcome, and sorry to here about your prob, as all above im afraid

 

[John Benton]

Hi Tradey, just had a look at the photos, and in my opinion I would take them off and start again. Once the poor glaze has been penetrated there's no chance of getting that out.

I have a saying "Buy cheap, pay twice" and I think you can confirm this is true. Good luck but get quality tiles next time.

 

[tradey]

Thank you all for replies. /humbled DIYer