How Do You Seal Slate Floor Tile?
Slate tile, like all natural stone, is porous, and should be sealed with chemical sealant during installation to prevent moisture penetration and stains. The sealing process isn’t complicated–it’s basically a matter of brushing the sealer onto it–but it needs to be done in conjunction with the grout sealing. This complicates things, since grout will stain unsealed slate during the grout-application process. The solution is to seal the tile right after installation but before grouting, then re-seal the whole surface after it’s grouted. Use your brush to spread sealer over the surface of the newly installed slate, starting at one corner of the tiled area and brushing in the direction of the slate grain. Brush the sealer only onto the surface of the tiles, taking care not to let it drip into the spaces between the tiles. (The grout will set better in the spaces if they’re not sealed.) Let the sealer dry for two hours. Apply a second coat of sealer. Let it dry overnight. Grout the tile,
