Efflorescence or...? Grout too light
Apologies for cross posting here & at John Bridge, but I didn't get any responses over there yet.
I just had tile installed in my basement and the grout has dried about 3-4 shades too light. The color *should have* almost matched exactly the color of the tile, but now have almost white grout lines.
I'm wondering if the too-light grout could be efflorescence? I did notice that at the very edges of the room against the walls, the grout color looked OK. But everywhere else it was too light.
For example, in the attached photo at the top right, my contractor had grouted between the marble threshold and the tile; and also under the door moulding; and those grout lines are the right color (which is why you can hardly see them there in the picture as they blend in); whereas everywhere else the grout lines are obvious.
The color is not uneven or blotchy looking -- just too light. When the tile is wet, it looks exactly how I want it -- but then it dries light again. I tried scratching at the surface; not sure if I went deep enough but the color underneath did not appear any darker.
We used sanded grout from The Tile Shop together with their recommended "flexible grout admixture". The tile is installed in a basement on top of a cement floor. Two different types of thinset were used, grout appears the same (too light) in both areas.
First thing I tried (on the recommendation of the Tile Shop whose grout it was) was an enhancing sealer (Aqua Mix Enrich 'n Seal). I did a test area and it came out terribly uneven and blotchy looking.
My next plan was to do a sulfamic acid wash, but I'm not positive I'm dealing with efforescence here. I suppose it can't hurt?
Then plan C will be to use a grout colorant.
Would appreciate any thoughts -- thank you!