How to Seal a Slate Countertop

Allow freshly grouted tile to cure for a week before sealing the slate tile. Wash the tile several times with clear water to remove all remnants of grout that remains on the tile. This step is very important because the sealer will seal grout remnants left on the tile making it difficult or impossible to remove and will adversely affect the tile's appearance. Cleaned slate tile must dry for several days before applying the sealer.

Select the type of sealer you wish to use on the tile. Topical tile sealants will remain on the surface of the tile and will wear away quicker than a penetrating sealer, which gives longer-lasting protection for the slate tile. Decide which finish you prefer for the slate tile. The choice for sealer finishes range from glossy, wet look or matte. Matte retains the most natural appearance for the slate tile. Water-based polyurethane sealants have a lower level of fumes and will not crack or yellow.

Wipe on a thin coat of sealer with a clean terry cloth towel and allow it to dry the recommended time before applying a second coat of sealer. Maintain good ventilation in the room because all sealers regardless of type have some fumes. Dependent upon the usage of the slate countertop, plan to reapply the sealer at least once a year.

Maintain the countertop by using a mild cleaner to remove food residue from the sealed slate.