Sealing, heat and the granite radon question

Sealing

The Natural Stone Institute states that sealing makes stone more stain resistant rather than stain proof, that many stones do not need sealing at all, and that a food-preparation area should use a non-toxic sealer safe for food use. The manufacturers differ by material. MSI recommends a penetrating sealer reapplied annually on granite. Daltile says natural quartzite should be sealed against stains, says its ONE Quartz needs no sealing, and says its Panoramic Porcelain, being non-porous, does not need sealing unlike natural stone. HanStone states its quartz never requires sealing. Laminam describes its porcelain as non-porous and not absorbing liquids or stains.

Acids and etching

The Natural Stone Institute states that products containing lemon, vinegar or other acids may dull or etch calcareous stones such as marble, that siliceous stones resist most kitchen acids but acidic cleaners are still not recommended, and that hydrofluoric acid attacks all stones including granite and quartzite. It refers etched areas to the stone dealer or a professional restorer for repolishing. That guidance is written for natural stone and does not cover quartz, solid surface, porcelain or laminate.

Heat

The manufacturers' own heat statements are more cautious than their reputations. Cambria advises trivets or hot pads against sudden temperature change. MSI states its quartz withstands about 300 degrees Fahrenheit without scorching and still advises trivets. LX Hausys describes VIATERA as heat tolerant but not heat resistant. Vadara states that direct or sustained heat can damage the surface and that outdoor installations are not covered by its warranty. Among the fired slabs, Neolith states resistance to high temperatures and UV rays and an absorption level close to zero, and Laminam states resistance to high temperatures and thermal shock. Wilsonart states its quartz is not recommended for direct outdoor exposure.

Radon and granite

The EPA states that there are currently no regulations concerning granite countertop radon gas or radiation emissions, and that neither imported nor domestic granite products require radiation testing. Its advice is to test the air in the home to determine the radon level, with the Surgeon General and the EPA recommending that all homes be tested. The published answer points at the house rather than at the countertop. This wording was read from the EPA's official January 2025 archive, which states that it is no longer updated; the live page wording was not confirmed.