1) After showering, the off-white colored grout turns into a gray color in small patchy areas. Once the shower dries up these patches fade away and look normal. Should I worry about this? Why it happens in patches, unless you sealed it with a non-breatheable sealer and didn't do a complete job, I don't know. But conventional grout SHOULD darken when it gets wet, and lighten when it dries. 2) The grout on the ceiling tiles seems to have shrunk. It might be on the verge of cracking in some places--I'm not sure. The white edges of the ceramic tile are slightly visible in some places. You might just be noticing it now. Once grout dries (within the first 72 hours) it won't shrink any more (not measureably, anyway). Let me ask you-- was it sanded or unsanded grout that was used, and how big are the grout joints?

Well, I'll throw out another wild one. I'm looking at those joints and they look wider than 1/8". And you said he used unsanded grout? And it appears this guy like to water his grout...I'm almost thinking that if he did a lousy job the first time around, he had problems with the unsanded shrinking during the curing. Especially if he likes water. Maybe a little flaking, a little cracking, a few pinholes opening up. Then he came back on the subsequent visit and grouted again over the existing grout to hide and fill in the blemishes. But that's just too crazy for me to speculate like that. I'm almost tempted to recommend a few ideas, mainly try a Q-tip dipped in bleach to see if the dark stuff low on the wall isn't mildew, and try a bit of an acid, even mild vinegar, on the white stuff down low on the wall to see if the white stuff is efflorescence that the acid will dissolve away. I keep coming back to your first photo: In the vertical wall-wall corner joint that is grouted, the right part of the grout joint looks like the original quartz color. the white stripe on the left part of the grout joint, as well as the white in the horizontal grout lines above the first course of tile, looks like efflorescence. The dark along the tub looks like mildew or moisture. But if the light and dark have been there forever, both efflorescence and mildew take a while to form. If your water has heavy minerals or it's heavily chlorinated, that might be a player. If is he used old bags of grout that were past their shelf life that could be an issue too. Or a contaminated mixing bucket. Or... But as you can tell, I'm just scratching my head and guessing. Does the white grout have a different texture? If you scrape the white with a fingernail, does it powder off? If it does come off, is there any of the true "quartz color" underneath it? Have you tried cleaning this grout at all? Like in my first post, I just keep leaning towards the idea that too much water was used. When I first looked at the photos of the upper walls, they looked like areas of good grout with a few blotchy dark streaks. Now I look at them and see the uniform light color being almost all efflorescence, or I'm seeing grout that has had the surface cream/pigment washed away, and the "dark blotchy areas" are actually the proper quartz color! I'd love to see this shower with my own eyes to figure it out. I probably have to take my son down to William and Mary for a college visit later this month. Bill, how about a road trip? A few crab cakes, catch a lacrosse game while we're down there, we can check out this shower all while taking my son for a college visit? Too bad the Orioles are going to be at Fenway instead of the other way around. Road trip!!! Seriously though, have you tried cleaning the grout with anything? A neutral pH cleaner and a bit of elbow...

I've tiled my own two bathrooms and my kitchen backsplash, so when my adult daughter's shower sprung a leak at her "new" (circa 1950) home, DH & I came to the rescue. Ripped out the whole tub surround (it gave up without a fight), fixed the plumbing, reinsulated, added backerboard, taped, mudded and commenced to tiling. Got complicated around the tub; being an old steel tub, it has about a 1" flange around the top edges as though it's supposed to bolt to something? We ran the backerboard down to within 1/4th" of that flange, did the tape /mud/dry time thing and then commenced to tiling. When I got to the grout, I must say, the grout was a tad drier than I'd liked for it to be, but I worked quickly and thought I'd done okay. We spaced the bottom row of tile to cover that backerboard/flange gap, which it did okay. Then I left my daughters to finish grouting the normal 1/4th gap around the edge of the tub. I would have used caulk, but since the gap varied some, the girls used the regular grout to finish off that bottom edge and the corners. Are you with me so far? It looked really nice. Now I notice a lot of little tiny cracks in the grout all over and I'm thinking I'll be okay to just smash in another coat of it. (She hasn't used any tile sealer, yet.) EXCEPT.........she called tonite to say the whole bottom row of that grout is soaking wet, coming out in big soggy clumps and some of the tile with it. My thoughts are that she didn't let the tile cure enough before going in and using it, so now we need to pull out all the soggy stuff and redo it from there. So, the questions are: did we handle the backerboard/tile/grout around that flange right? Or is there just enough movement in a steel tub to disallow a grout (vs caulk) to flex. If that makes any sense.......And the second question is: am I on the right track to fix it? How long does it REALLY take for tile to cure enough to take a shower? Please tell me I don't have to take down this whole job.....this is a single mother with a TEENAGE daughter who will just DIE if she doesn't get to shower. Thanks for reading this far............. mm

So I have a little more information. The grout used is Mapei’s Ultracolor Plus, which supposedly does not require a sealer. We've had the tile installer out to inspect, and they scratched at the black spots with an exacto knife and found that the stain is only on the surface and could be scratched away. Also in the few days of no use since they scratched out some grout, the remaining black stain did not go away or “dry up.” They did not identify any specific source or reason for the stain but concluded they will just remove and re-grout with more of the same product. It‘s not clear why we’d expect a different result the second time around. They’re scheduled to come re-do the grout tomorrow. Any other questions I should be asking or things they should be looking into? Has anyone had a familiar problem with this or any other kind of grout? Thanks!