Concrete is great for outdoor countertops, as you can see in this project we completed in Frisco, TX. We created three separate countertops and knockouts (open areas created in the mold) for a grill, trash receptacle, and beverage cooler. We applied an acid stain over the entire countertop to create a more interesting finish. Outdoor countertops are always more challenging than interior ones, mostly because we are usually building them on stone bases (which are never level no matter how much the stone masons try) instead of wood cabinets (which usually are). It requires a fine touch to properly install these.
As with floors, acid staining concrete countertops will create a very unique look, and as with floors, we just kind of direct it to where we want it to go. We can't ever get an exact idea of the final result because acid stain "does what it does." Another way we sometimes go is using a dye stain. Because dye stain isn't reactive (instead it's wicked into the concrete), it doesn't create as much "mottling" as an acid stain, but the color is more controllable. After molding, leveling, and pouring these outdoor countertops, we give them a few days to cure before applying the acid stain. We don't usually acid stain all of our concrete countertops, but here it works very well with the stone base theme. The acid stain was applied after we stripped off the mold and did some minor touchups. Depending on the final look that the customer wants, we may either spray the stain down or lightly sponge it on, because each creates a different look.
On these outdoor countertops, we chose to spray them on. We applied a couple of coats, let them react, cleaned up the residue, and then sealed them. Sealing is a critical part of the process. It can dramatically enhance the look of the acid stain and reduces the possibility of the countertops being stained from stuff that regularly comes in contact with them like wine, lemon juice, mustard, etc. However, there are different levels of protection, which all depends on the type of sealer you choose. Books have been written about this topic, and in the next project, we'll try to give you a quick primer so that you can decide which will work best for your project.