What Is a Granite Countertop Sealer?

Homeowners and contractors who install granite countertops in kitchens, baths and bars often choose it for its beauty and durability. To maintain the integrity and appearance of this stone, one must apply a granite countertop sealer before use. This product protects the granite from discoloration, oil stains and water damage. Formulations available from retailers are liquids and waxes that one also can use to give granite an appealing shine.

Formed by pressure and cut from natural deposits on mountains, granite is a type of stone composed of millions of crystals. The color and structure of each piece of granite depends on the geologic history of the location that produced the stone. Unlike countertops created from synthetic materials, granite is porous, with layers of open cells that will absorb liquids. Quarries in different geographic regions produce granite varieties with different levels of porosity.

Cutting granite to remove it from its source also creates small cracks inside the slab and on its surface. These cracks might not be visible to the naked eye or detract from the stone’s usefulness or beauty. After one installs the granite slab, however, the cracks are entry sites for dirt and spills that can damage the stone.

One must choose which type of granite countertop sealer to use when protecting the stone. One generally applies water-based formulas to the surface of a granite slab to create an external barrier to oil and water. A penetrating granite countertop sealer seeps into the layer of crystals below the slab’s surface and creates an internal barrier that protects the integrity of the granite. Manufacturers produce penetrating sealers from a variety of chemicals that have oil- and water-repelling properties.

Before applying either type of granite countertop sealer for the first time, it is important to make certain that the stone is completely dry. If it is necessary to clean the surface of the granite with any liquid before sealing it, one should wait 24 hours or more before applying sealer. This allows the stone to release any moisture it absorbed during the cleaning.

To apply a granite countertop sealer, one works on small sections instead of coating the entire slab at once. As the sealer begins to dry on the first section, one applies a second coat on the same section. After the waiting period recommended by the manufacturer, one buffs and shines the first section before moving to the next area of the countertop. A shop rag or similar cloth is the only material required for applying the sealer and buffing the granite.