Stone Tile Gurus - Granite Darkened After Mortaring
Cross-posted from Flooring, because I'm not sure which forum Bill V and Mongo (the BR and tile gods!) check most often - this forum seems more active. :-)
Hello Stone Tile Gurus,
Yesterday I laid my first self-installed granite floor - moderate size bathroom, 1/16" spacing for 12" x 12" Beige granite tiles - and the tile darkening that I assumed yesterday was just due to the tiles absorbing fluid from the thinset has only lightened marginally in the past 24 hours. I used Mapei white unmodified tile mortar (thinset) mixed with Mapei Keraply latex additive (instead of water) to get the (hopefully) strongest bond possible to the substrate. I was careful to select white, not grey, thinset to insure that the natural stone color wasn't darkened.
The lippage is minimal, the grout lines pretty well straight with the 1/16" spacing, and the thinset seems to be cured from the little I can access between the grout lines and at the edge where I've yet to install the transition. My fear is that the darkening of the tiles may not be self-correcting as they dry. The tiles were unsealed (I was planning on sealing before grouting, but didn't want to seal before laying for fear it would negatively impact the bond with the thinset) and only the ones cut by a wet saw were moistened before laying. Does the darkening mean that the tiles have absorbed the latex additive and been permanently stained from beneath, or are they just taking longer to dry than I've seen on granite counters?
I'd really hate to have to take them back up - the bond seems reallly good and the spacing/levelness I'm really happy with, so I'm hoping time will cure what ails them. How long should it take for 12"x12" porous granite tiles to dry out to their final color? These were purchased to coordinate with the vanity counter that's going in, so I'm really hoping the thinset hasn't darkened them permantly. Thoughts?