- Proper installation of the grout is crucial for the later sealant application to work properly. There are two basic types of grout--sanded and unsanded--which refers to whether the mortar contains sand. Sanded grout is for grout lines of 1/8 inch or wider, and is standard in ceramic, porcelain and most clay-based tiles. Marble, slate and other stone tiles generally set to 1/16 inch, and require unsanded grout to fit in the narrow lines. Either type needs sealing. Let the grout ``slake'' for 10 minutes in the bucket before application to allow the chemicals to meld. The grout should sit in the lines of the tiles for a minute before you wipe off the excess with a damp sponge.
- Curing the process by which the grout completely dries and sets to its final state, so there will be no further movement or moisture transfer. Different types of grout call for different curing times before sealing--some as little as two days. Generally, though, you're best off waiting 30 days to ensure that it's fully cured. During that time, the grout is vulnerable to stains, so use the area carefully. To prepare the grout lines for sealing, clean the grout thoroughly, using a 50-50 solution of bleach water and a stiff toothbrush. Let it dry completely. Make sure there are no stains on it before you seal it.
- Sealant comes in two general types: surface, and penetrating. Surface sealant sits on top of the grout and forms a shiny coat, and is the best choice to go with high-glaze tiles. Penetrating sealant soaks into the grout and is less shiny, making it better for flat or natural-stone tiles. Both kinds are usually applied with a thin sponge applicator on the sealant bottle, though for very thin grout lines you may want to use an artist's detail brush. Keep a damp cloth handy to wipe off any sealant that gets on the tile surface. Let the sealant sit for a day before resuming use of the area.
