Wow. Great questions. I wish I knew the answer. I would not want to try anything that could further blemish the work and might suggest you make up a tiny sample board and test the results.

Tile, Grout and sealer then try the fix.

I bet Bill would know.

JW

Do you mind me asking(in light of your problem)if you like the look of two different grout colors in the bathroom?

That's a good point JW. Maybe I shouldn't be doing experiments on the actual floor.

Paige, I love the two different grout colors. The gray is perfect with the carrara hex tiles, but I really wouldn't want gray with the subway tiles. I live in nyc and gray grout with subway tiles is too much like the actual dirty subway for my tastes! I also didn't want white grout on the floor because I can't imagine spending the time to keep it flawless. So for us it was an easy decision.

Now if only I could figure out the best fix for getting the gray grout back to gray!

{{gwi:1439843}}

Here is two tone grout installed out in UBC Vancouver. The floor is a mix of Italian White and Black Marble. To insure this was done perfectly I advised my clients (under my setter's recommendation) to allow the black grout to cure and be sealed. We left the black grout for over a week I think and then I installed three coats of enrich in seal. Then we taped off the floor a couple days later and did the white.

{{gwi:1439846}}

Same process.

Be careful with two tone grout installs. There is no room for error. And a mistake is set in stone sort of speak.

Make up that test board and don't practice on your new floors.

Good Luck.

JW

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It sounds to me like too much water was used in the cleanup of the floor grout, and now you're getting a little efflorescence on the top of the grout surface. If you hadn't sealed it, you could've scraped it down a bit and skimmed it with grout. At this point, though, you're better off digging out the grout joint, refilling it, and then resealing after it dries.