How to Seal Marble Countertops: Protect These Porous Surfaces in 7 Steps

It’s worth checking each month to see how the seal on your marble countertops is holding up. You’ll know it’s ready for resealing if liquids absorb into it too quickly. You can test the sealant in two ways.

Put a few drops of mineral oil on an out-of-sight section of the counter. If a dark stain shows up when you wipe the oil away with a dry cloth after 10 minutes, it’s time to spread the sealant. And don’t panic about the stain—mineral oil evaporates well from stone surfaces, so it should disappear within an hour.

Alternatively, sprinkle drops of water onto the marble. If it absorbs into the stone rather than beading on the surface within 15 minutes, crack open the sealant. 

Thoroughly clean marble before sealing so you don’t trap mold and bacteria-creating debris on the surface. 

Remove crumbs with a clean, white microfiber cloth, and then clean the marble surface with a neutral marble cleaner or a mild, pH-balanced dish soap and warm water solution. Avoid harsh acidic cleaners, which can dull your marble's natural shine. Use a dry cloth to wick away any excess moisture. For hard-to-remove residues, you can blot with fast-evaporating acetone.

Allow the marble to air dry overnight—you don’t want to seal in any lingering moisture. 

To avoid getting sealant on your backsplash, painted walls, or floors, apply painter’s tape along the edges of your countertop and lay down drop cloths. 

As a precaution, test the sealer you select on an inconspicuous corner of your marble countertop before covering the whole surface. Before you get started, ventilate the space well to improve your indoor air quality—sealers often contain volatile organic compounds (VOCs) that emit harmful gases. Open windows and, if you have one, turn on a fan. 

Put on disposable gloves when applying the sealer and wait to see if it causes discoloration. Normally, you should only have to wait around 15 minutes, but always check the manufacturer’s instructions.

If the sealant results in discoloration, contact a marble countertop specialist near you for advice on the best product.

Pour some sealant into a portable, wide-mouthed container to minimize messy drips, and use a foam paintbrush or applicator pad to apply the sealant. Load the applicator generously (but not so much that it drips) and use overlapping, even strokes. Work methodically in sections to ensure all areas of the countertops receive an even covering.

After 15 minutes, remove any excess sealant on the surface with a dry, clean microfiber cloth.

If your marble countertops suck up all the sealant within 5 or 10 minutes, apply another coat to provide sufficient protection. The wait time between coats depends on the product, but you usually only have to hold off for 15 to 30 minutes before rolling up your sleeves again.

Maximize your marble countertop’s luxurious luster by buffing the surfaces after sealing. Work across the countertops with a clean, dry, soft microfiber cloth. Use circular motions and replace the cloth with a fresh one once all the sections are damp.   

Allow the sealant to cure for another 24 hours before placing countertop appliances and accessories.