This was a lesson. And the lesson is: avoid white natural stone, unless you have a very light grout. But even then, dirt will accumulate in the stone, giving it a dirty appearance.
The client had selected a dark sanded grout and the natural stone has craters and divots, that hold the dark grout, creating a dirty appearance, despite rigorous cleaning. Read to the end to see the solution we came up with.
Typically, a new tile floor – which is mostly tile and maybe 5% grout surface area – sheds grout for a couple cleanings. In this case, the grout was 40% of the floor’s surface area, and, being dark, contrasted with the stone, which, again, held pockets of the grout in its surface.
This floor was about 160 square feet with a fair amount of angles.
A schulter backing was installed over backer board.
The stone was difficult to clean up, if untreated. So it was sealed.
Believe it or not, these are not manufactured stones. They were triaged to interlock with millimeter-specific sorters, and glued onto a mesh. So, the pattern is indiscernible.
After several days, this is what we had:
The dark grout wanted to get stuck in the craters and divots of the stone. In the end, after using bleach and an eco-friendly cleaner, we were able to make it look better. Finally, a low-pressure pressure wash was recommended, and another sealant pass.