Food-safe stone sealer and enhancer protects natural stone surfaces such as countertops or tiles from moisture and staining by coating the stone with a resistant barrier. Natural stone like marble, travertine or granite is porous, and although many manufacturers apply a finish, this wears over time and the pores are opened, making the stone vulnerable to stains, discoloration and odor absorption. Sealing the stone prevents food, water and chemicals from damaging the stone and from transferring bacteria and smell.
Penetrating stone sealer repels liquids, preventing them from being absorbed into the stone. It does not actually coat the stone in an impregnable layer, however. If vapor is not allowed to transfer in and out of the stone, it would find its own way to escape, which can cause cracks, spalling and erosion. Stone sealers work by coating the pores with a layer that prevents the absorption of liquids but allows air to pass through. Sealer used on natural stone countertops must be nontoxic and safe for use with food. If a sealer says that it is food safe, the manufacturer is identifying it as containing no harmful chemicals that might pass into the food prepared on it.
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Sealer and Enhancer
Enhancing sealers have the same protective properties as penetrating sealers but have the added benefit of enriching the natural color in the stone. Because they use more water, enhancer sealers dry or dissipate from the stone more rapidly than straight sealers and must be applied more often. Sealers that contain enhancers should be tested in a small hidden area first, to ensure that the final color will be what you're hoping for.
Enhancing sealers will not prevent scratches, etching or pitting on the surface of the stone. They are not waterproof or stain-proof barriers. Instead, stone sealers and enhancing sealers give you time to clean up a spill before it is absorbed into the stone. If liquids are left standing on the stone, staining may occur even if it has been sealed. Most enhancing sealers will resist oils, but hot oil, such as cooking oil or grease, can melt the resins in the sealer and result in stains. For this reason, oils should be cleaned from your stone surface immediately. Acidic foods like tomato sauce or lemon juice will etch the surface of some natural stones, such as travertine and limestone, even if it has been sealed. Etching looks like hazy white marks in the surface of the stone. These can be removed by polishing or honing.
Enhancing sealers typically require reapplication at least every other year. Spills, cleaning and normal wear and tear cause the resins to break down over time, leaving the stone vulnerable to stains. Stone surfaces that receive a lot of use and cleaning might require more frequent yearly applications. You can test your stone surface by applying some water to a hidden area of the stone and leaving it for about five minutes. If the stone darkens and this does not fade after drying, it needs a new coat of sealer. But if the water beads, the surface is sealed and does not need resealing.