How should tile/grout joints be sealed?
Tile grout joints can be sealed with a penetrating/impregnating type grout sealer. Sealing grout with these products will not change the appearance or color of the grout, and they are designed to prevent moisture from absorbing into the grout where it would otherwise leave a stain. However, sealers do not stop topical dirt buildup, which can be removed easily with a mild neutral cleaner if the grout has been sealed.