Concrete kitchen countertops are a durable, functional option for homeowners who want a handcrafted product with character and warmth. Concrete is formulated using a variety of ingredients, so every concrete countertop is different, with small distinctions of colour and texture. A food-safe sealant not only protects the countertop from the food that touches it, but protects the food against possible contamination from the concrete. Like granite, concrete is porous, and can suffer stains, heat damage and scratches, as well as damage from acidic foods and ultraviolet light. While all food-safe sealants protect your food from contamination, no single sealer protects the countertop against all damaging agents. Choose a sealant based on how you plan to use the countertop.
Apply a sealant that is waterproof and has good stain- and scratch-resistance if you plan to chop vegetables, roll pastry or place raw food items that can stain, like blueberries, directly on the countertop.
Use a sealant that has good heat resistance if you will set hot dishes or pots and pans directly on the countertop.
Treat the concrete with a product that offers protection from ultraviolet light damage if the countertop is exposed to direct sunlight every day.
Use a penetrating food-safe sealant if the countertop will not come into contact with acidic foods and will not be subjected to water. This sealant can be damaged if you slice lemons or spill tomato sauce on the countertop. This sealer is not a good choice around kitchen sinks, either, because repeated exposure to water will weaken the seal. Penetrating sealers do not flake or peel, are impervious to sunlight (UV exposure) and have good heat resistance.
Apply a topical food-safe sealant for shine or for stain, heat or UV resistance. Topical sealants include wax, epoxy, acrylic and urethane. Wax sealants are not scratch-proof, but do give the countertop an attractive shine. Acrylic-based sealants can also suffer scratches, but protect the concrete from stains and ultraviolet light. Acrylics offer some protection from heat damage. Epoxies are expensive, but provide excellent stain resistance and add a lustre to the concrete. Epoxy sealants are not UV-resistant, and they scuff and scratch easily.
Select one of the more recently developed hybrid sealants for more thorough protection. Hybrid sealants include topical and penetrating products, many of which are water-based and provide protection from many, but not all, damaging agents. Hybrid sealants are available in several food safe formulations, each of which has different protective properties.
Check the durability of each sealant type you consider. Wax sealants, for example, must be reapplied more frequently than any other type. Look for convenience as well as function. Some sealants must be applied in a two-step process, while others require a simpler, one-step process.
Hybrid epoxy sealants are tricky and complicated to mix and apply, and may require the help of a professional. Lithium silicates provide a hard, transparent surface, but the sealant must have time to cure on the concrete before the countertop is usable.