Grout is the material that fills the seams between tiles. Grout is not needed to stabilize tile, because mortar already holds the tile in place without any extra help. Most grout you will be using is called sanded, meaning that grout contains sand. Sand is used by manufacturers not just because it is literally dirt-cheap but also because it is a good material for what is a simple job: filling in a hole. Sand is porous, which means that grout is porous.
Unfortunately, once the grout has been applied and dried, it is ready to absorb any liquid that comes its way, like water. By penetrating the grout with sealer first, you are pre-empting water and other liquids from penetrating the grout. Grout sealer is that simple.
What Is Grout Sealer?
Grout sealer is a necessary component of the tile installation process. It serves to prevent moisture from working its way into the grout and under the tiles.
Do You Always Need Grout Sealer?
Yes, you need it, except when you happen to be using epoxy-based grout. Grout sealer is not needed with epoxy-based grout, because this type of grout naturally sheds water with no additives needed.
SpectraLOCK from Laticrete is one popular brand. Epoxy grout is more expensive and can be tricky to mix.
Is It Easy to Apply Grout Sealer?
Grout sealer is easy to apply but tedious. The smaller the tile size, the more grout you will have. If you installed small mosaic tile, for example, you're in for a lot of grout sealing. If you installed a large format tile, your sealing job will be exponentially easier and faster.
This matters because using the brush or roller sealer applicators on an entire roomful of small tile can take up a whole weekend. In this case, try the spray-on type of grout sealer.
How Long Should You Wait Before Sealing?
After installation of the tile, you should wait until the grout is 100 percent dry before applying the grout sealer. Any presence of moisture in the grout will prevent the grout sealer from soaking in. Keeping a freshly tiled room warm aids in curing grout.
Best Way to Apply
You have three choices as to application: brushing it on, rolling it on, and spraying it on.
- Brush on: The sealer itself is milky in appearance and is applied directly to the grout itself with a brush tip. Avoid getting the grout sealer on the tile itself, though a bit does not really matter. The brush applicator is difficult to use because the sealer doesn't feed smoothly into the brush and sometimes requires you to go back and reapply in dry areas where sealer failed to apply.
- Roll on: Rollers allow you to keep moving down the tile seam line, with little or no reapplication efforts. Rollers are not perfect, but they are better than brushes. The sealer remains relatively close to the seam line without slopping too far over onto the tile surface.
- Spray on: Dread the idea of laboriously following the grout lines with an applicator tip? Then, just spray it on. The theory behind spray-on sealers is that sealer fluids soak into porous materials (sanded grout) but not into smooth surfaces (the glazed surface of ceramic or porcelain tile). So, even though sealer will end up on the glazed surface, it should wear off over time, in theory. You pay the price for this convenience because you have more tile surface cleaning later on.