Shall not the tile grout Been More Flexible — The problem with this tile installation, open joints where a cement-based grout was used at the juncture between the horizontal and vertical planes, might have been prevented had a mildew-resistant flexible grout been used instead.
Who Wants Powdery Tile? — This surface of this floor tile shows evidence of efflorescence caused by the water-borne migration of the salts in Portland cement-based setting materials.
Discoloration, shading and mottling are probably the most common causes of grout-related complaints. Many contributing factors can be at play in such situations — so many, in fact, that I’ll list the top 10 here.
1. Grouting done on different days or by different crews.
2. Excess bonding mortar squeezed into joint. Proper depth of tile grout is two-thirds of the tile thickness.
3. Tile grout not mixed properly — either not sufficiently mixed, mixed too slowly or mixed too quickly.
4. Over glaze. This occurs when the grout comes into contact with the glaze over the edge of the tile, which alters the drying and hydration time in portions of the grout.
5. Use of cleaners before the grout has set.
6. Use of old tile grout, particularly when the components of the product have separated within the bag.
7. Mixing water contaminated by chemicals.
8. Excessive cleanup causing water to wash pigment out of the grout.
9. Chemical deposits that migrate from the mortar bed to the grout surface.
10. Inconsistent joint sizes.
We suggest that you may be able to advoid these problems by dampening the grout joint before grouting, using polymer-modified flexible grouts, damp curing the grout and sealing it.