First step: the mold. Exact measurements are crucial. And be sure to build the mold with smooth material, unless you want lines, grooves, texture, etc. to show up in the concrete. We used a melanine board. Here’s the mold in its basic shape and early stages. You can see where the sinks will sit. The blue tape is to keep caulking from contaminating the the top of the mold. Stain does not penetrate the caulking… But you need caulking to seal around the sinks, so water doesn’t leak out of the concrete. Most sources suggest you use black caulking, and we did, because, I believe, it’s less visible if it does come into contact with your concrete. A good resource to consult is Concrete Countertops by Fu-Tung Cheng. Also, make several sample pieces to test stain colors on.



The next step is to add your faucet knock-outs. Then you add rebar and remesh. The technical details are numerous, so again, please consult a reference book. The end result looks something like this:



And now you’re ready to mix and pour your concrete. We used Quickrete 5000 concrete, bagged, because it came pre-mixed with aggregate, portland cement, and fibers, and we had a small project. We also added Counter-flo, which reduces water content. Find a specialty concrete store for such items. Places like Home Depot don’t cut it. Especially when it comes to stain… Once the concrete is poured, you need to vibrate it from the underside, and the sides, of the mold, to release the air bubbles. (Picture 2 below.) Rent a cordless vibrator for best results, or use a combination of a palm sander (sans sandpaper), a reciprocating saw, with blade removed, and a hammer.



Once your concrete has cured, remove the sink molds and the faucet knock-outs. Flip it over, and see what you’ve got. And that’s the scary part. You can run into a myriad of problems in the process. Efflorescence, water discoloration, ghosting, cracking, holes. Luckily, most of them are fixable, and defects add character. We found a lot of small holes in ours, probably because the mixture was too dry. A simple slurry mix easily fixes this problem, and adds, in my opinion, a more stone-like appearance once it’s stained. Some people even add defects like this intentionally, to get this apperance. If the holes are very large, use an epoxy.



We sanded it before and after adding the slurry.



Once you’re satisfied with what you’ve got, let the slurry cure. In the meantime, play with your stain on your sample pieces. Go to a specialty store, or order online, because, again, Home Depot-like products just don’t cut it. You want the good stuff. Staining is a process. You have to apply the stain, neutralize it, and rinse it off, over a period of several days. It’s best to do this outside, for obvious reasons. When you first apply the stain, it often looks a totally different color than what it should end up as. And once it dried, it really doesn’t look very good. Neutralizing and rinsing it brings out the true color. Once you’ve got what you want, move onto your countertop. We added a wet look laquer to ours. This isn’t often recommended for places like the kitchen, however.





Not too bad for our first concrete countertop project, is it? Well, okay, I think it’s breathtakingly beautiful, but I’m biased.










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