Can I safely seal and waterproof my butcher block countertops?
There are a variety of options for permanently sealing and waterproofing butcher block wood countertops, commonly used in kitchens. When considering sealers, there are two types available: penetrating and topical. A penetrating sealer soaks into a substrate such as wood, concrete or stone, and it seals the pores from the inside. Once it cures, moisture is not able to penetrate the surface.
Natural oils are excellent penetrating sealers, and they’re nontoxic, easy to use and make the wood look rich and luxurious. When there's a scratch or gouge, or the wood begins to look aged, it's relatively easy to spot repair by sanding and blending a little oil into the remaining wood to bring it back to life.
Topical sealers, on the other hand, have won homeowners over because they create a thin, protective film on the surface that is resistant to scratches, keeps out moisture and dirt and (supposedly) lasts a long time. Sounds like the obvious choice, right?
Not so fast! Made from a variety of chemicals such as urethane, polyurethane, epoxy, varnish, acrylic, aluminum oxide and various combinations of chemicals, topical sealers can off-gas VOCs for months or years after they're applied. While there are some new water-based products on the market that have low VOCs, most still contain solvents and dryers that are hazardous to your health. This is certainly not what you want on your kitchen countertops.
Not only that, but a topical sealer is nothing more than two to three layers of clear plastic that can be scratched and eroded over time. While they may seem tough, their skin can be pierced by sharp objects or strong acids and alkaline foods. Once the skin is pierced, moisture can get underneath the surface, which can cause mold and mildew.
The real issue with topical sealers is that they're difficult to spot repair. That's because sanding through the surface and recoating makes the area stand out and look completely different from the rest of the woodwork. In that situation, the only solution is to completely resand the wood and recoat it, which is time-consuming and expensive, as well as having health and environmental implications.
An alternative solution is to use a product that combines natural oil and beeswax, which creates a penetrating inner seal and water-resistant finish.
As always, be sure to read the label on all products, and look for a third-party certification by highly respected organizations such as GREENGUARD and GreenSeal before you purchase.