In the cleaning pre-inspection, determine if the grout is sealed or not (if previously sealed, you may not have to do it again). After the grout is cleaned and starting to dry, you need to decide what sealer to apply. In most cases, you will apply Premium Grout & Stone Sealer. The only time you will not apply Premium Grout & Stone Sealer is when a colored sealer is needed to even-out the color of the grout, or a darker grout is developing a white haze on its surface as it dries. This is called efflorescence and needs to be removed before applying a sealer. This phenomenon is caused by water; therefore, Premium Grout & Stone Sealer should not be used. Solvent-Based Grout Sealer and Clear Grout Sealer with color additives can be applied after 24 hours.