Concrete countertops should definitely be sealed because, unlike granite and some marbles, concrete is a very porous material. Due to this it can easily be stained by food, beverages and other liquids that are sure to come in contact with the countertop over the course of its life. Penetrating sealers protect the countertop from these stains and make it much easier to clean. Sealers come in two styles -- sealers and enhancing sealers. Enhancing sealers contain chemicals that will darken and reveal vibrant colors that are contained in the stones that make up your concrete, while also sealing the countertop. Straight sealers will only seal the surface and in some materials may result in a very mild darkening of the surface.
Sealing the Surface
Clean the surface of the countertop with the canned air to loosen and remove any particles that are not a part of the surface.
Fill your cup with a small amount of sealer.
Dip the foam brush in the sealer. Do not let the brush soak.
Brush the surface of the counter top with the sealer in even smooth strokes. Overlap strokes as you apply it across the countertop.
Replenish the brush and cup of sealer as needed.
Allow the sealer to penetrate the countertop.
Check the countertop in 30 minutes. As the sealer does its work, it will penetrate the stone and then, as it hardens it will expel excess sealer to the surface. If you have puddles of sealer on the surface wipe them up with a rag. Otherwise, they will harden and leave a hazy appearance on the surface.