I tiled my shower niche last night, this is my first step tiling the bathroom, today I'll move on to walls etc. I used white thinset, and some portions of the tile turned dark after installation. I believe they soaked up moisture from the thinset, and theoretically will dry out and lighten up again.

Can anyone confirm? I finished about 8 hours ago and it's still dark so I'm starting to wonder.

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  • White thinset is always used on light colored marble, you used the right stuff. Give it a few days, it will turn back to the dry color. I see Ditra around the niche, you planning on running Ditra in the east of the shower?
    – Jack
    Nov 28, 2013 at 23:37
  • Thanks! I knew this was technically the correct way, I was worried regardless though. About the membrane, no, just surrounding the niche. I used schluter kerdi-niches and the edges where they met the cement board had to have a waterproofing membrane thinsetted across the seam. In their demos they always had membrane covering the entire shower, but that's because they use it over drywall. I'm using cement board so I just did the seam. Oh, and that part was done a week or so ago, that grey thinset is dry and will be covered with white thinset for tiling (I had some grey left over from the floor) Nov 29, 2013 at 2:59
  • Please please do consider using Kerdi everywhere from and for the floor pan and up onto the walls as far as the walls could possibly get wet. Cement board still allows water to pass through. If it was a tub with shower is one thing, but a full shower requires the extra moisture protection, especially at the base. If you have a PVC pan in place is good, I usually add redundancy in an important spot as a shower floor. BUT, if the floor mud is already set for the thickness of the floor tile, then that's that. Then, there is always Red Guard, good stuff, that is what I used along with my PVC pan.
    – Jack
    Nov 30, 2013 at 1:56
  • Kerdi is what I meant in the first post.... Ditra is for floors....
    – Jack
    Nov 30, 2013 at 1:59
  • thanks Jack, I forgot to mention this is a tub with shower. I put tar paper behind the cement board, and overlapped the lower edge onto the lip of the tub . Of course that area will be grouted in so I'm not sure how it will work, but that's what the recommendation was so I did it.. Nov 30, 2013 at 13:30

1 Answer 1


White thinset is always used on light colored marble, you used the right stuff. Give it a few days, it will turn back to the dry color. I see Kerdi around the niche. Are you planning on running Kerdi in the rest of the shower?

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