The Best Concrete Sealers Tested in 2023

Seal-Once Nano + Poly Concrete and Masonry Sealer combines proprietary penetrating nanotechnology with polyurethane to provide durable, long-lasting protection. It penetrates concrete pores to protect against water damage with a stable, water-resistant shield inside the concrete surface. It claims to prevent efflorescence, cracking, spalling, mold and mildew growth, lime bloom, and freeze-thaw damage.

We liked the eco-friendly aspects of Seal-Once, which is safe around children and pets when completely cured. It does have a bit of an odor, however, and we had to open the windows in the shop to air out the smell during application to a concrete paver. We used a brush to apply the sealer, which was milky at first but cleared up as it dried. After 24 hours, a film was visible on the paver, but it was attractive—it didn't change the color of the concrete, just added a uniform finish. We took it outside and ran it through a battery of tests, including mud, grease, de-icing salts, and rubbed-in sand. What's more, this specific paver happened to be sitting on the ground near a downspout, and when we got freezing rain, the water covered it and froze about an inch thick on top. We couldn't have planned a better ice test!

After testing, we power-washed the paver and noticed a bit of dulling where the de-icing salts were applied. We double-checked the specifications and found that the manufacturer does not guarantee protection from chemicals. Water still beaded on the surface and didn't soak in, making this sealer well suited for use on concrete where de-icing chemicals will not be used. In addition to penetrating the concrete to coat its internal pores, Seal-Once Nano + Poly creates a durable surface coating that protects against UV fading, wear and tear, and water damage.

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Get the Seal-Once concrete sealer at Amazon, Ace Hardware (5 gallons), The Home Depot, or Seal-Once.