From your personal experience,
- do grey color C2 cementitious tile adhesive stain white marble tiles?
- do white color C2 cementitious tile adhesive stain black marble tiles?
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It only takes a minute to sign up.
Sign up to join this communityYes, mortar can cause staining and can show along the edge of tiles. It's advisable to use a mortar that's the color of the tile, and some mortars are specifically designed for natural stone.
Thinsets/adhesives/grouts that contain water can permanently discolor adjacent portions of some marble tiles, it does not matter what color it is. In those situations, epoxy "thinsets" and grouts can be used.