If staining isn’t as big a deal for you then a good sealer choice for concrete countertops is going to be a penetrating sealer. These do not create a barrier on the surface of the concrete, instead these sealers penetrate deeply in it and seal off the capillaries and pores to prevent liquids from seeping in. The biggest advantage of these sealers is that placing super hot pans, cutting with knives, etc. won’t damage the sealer. It’s not on top of the surface (that doesn’t mean you can’t scratch the concrete itself, but that does take some trying).
Penetrating sealers have almost no effect on color or appearance, you get concrete as close to natural as possible but they are not as effective at stain resistance as the topical sealers, particularly against acidic liquids. Wine, lemon juice, oil, and other foods can etch or stain the countertops fairly quickly if you are not diligent in wiping them up. Why is this?
Topical sealers prevent contact with the concrete, no contact – no staining/etching as long as the sealer is not physically damaged. While a penetrating sealer also seals, it does so from below so liquids will work on the top of the concrete and though slowed by the closed off pores, eventually “chew” their way into it.
Just as an FYI, this black concrete tabletop was sealed with a matte polyurethane which is a topical sealer. It offers the best of both worlds – good to excellent stain resistance (again dependent on the type chosen) and good resistance to heat / wear and tear found in kitchen or bathroom environments while still maintaining the more “natural” look of concrete.
Also keep in mind, in spite of what the salesman promises, no granite, marble, stainless steel, Corian, Silestone, or Formica countertop is 100% stain / heat / scratch proof, they all will, just to differing degrees. We do offer high gloss versions of topical sealers as you’ll see in the next “Best of” project.