Grouting tile gives it a finished, professional look and prevents dirt and debris from getting clogged in between the tiles. Grout can be applied in its natural white color, but tinting it makes it less apt to show dirt and detract from the beauty of the tile. When applying grout to tile, mixing it to the proper consistency makes the job easier and ensures the grout won't crumble and loosen when the tile is washed or exposed to moisture.
There is no hard and fast formula for mixing grout to the proper thickness. Start with a small amount of grout mixture in a small container, slowly add water to it and gently mix it with a putty knife. When the mixture resembles thick cake batter and sticks to the end of the putty knife, it is the proper consistency.
Thin and Thick Grout Perils
If the grout mixture is too thin, it will not properly harden and as soon as it is exposed to water, it will disintegrate and fall out of the crevices between the tiles. Grout that is too thick will not fully seal the tile, as its viscosity will prevent it from reaching the bottom of the cracks. Overly thick grout will also adhere to the surface of the tiles and be difficult to remove when the job is done.
Good vs. Bad Grout
Grout powder, which is mainly comprised of Portland cement, should have the consistency of all-purpose flour and be free of clumps or lumps. The mixture is highly sensitive to moisture exposure, which is why it is typically enclosed in an airtight plastic bag inside the container or bag in which it is packaged. If the grout has any clumps in it, it has likely been exposed to moisture and will not set up properly. Discard any grout mix that is not free-flowing and powdery.
Tips and Hints
Since mixed grout quickly dries out, only mix enough in each batch to last about 30 minutes. Have a damp sponge handy to lightly wipe each seam in the tile as it is grouted, but avoid too much water in the sponge, as it will adversely affect the grout and make it crumble. If you live in an arid climate with low humidity, lightly cover the grouted tile with damp paper towels and change them as they dry out. If possible, run a humidifier in the room to keep the air moist. The slower grout dries, the sturdier it is. Grout that is dried in a moist environment for at least 48 hours will usually last indefinitely.