Concrete Countertops

by Chris N
(Trenton, MI)

Q: My Landlord is renovating the apartments in my complex and is installing concrete countertops.

However, I think he isn't doing it right. The countertop in my neighbors apt. is very pourous and just has a coat of paint on it.

I dont know what kind of paint, though. is this a health issue?

A: Concrete countertops are great but funny things, Chris.

Built correctly they'll last basically forever. But with kitchens, you have to take measures to keep concrete countertops from staining. If, by "porous" you mean scratchy, like sidewalk concrete, then no, concrete countertop makers don't generally do things that way.

The materials that go into a concrete countertop are inexpensive. What makes a good concrete countertop is the specialized labor that goes into it, and much of that labor is applied toward finishing the countertops. First the concrete must be cured properly. You can't just leave it out to dry. Once the curing process is complete (which can take several days), the finishing process can begin. Here's one fairly basic finishing method for concrete countertops, and I've simplified the steps greatly:

1. Clean the concrete with a solution of 10 parts water and one part muriatic acid. This alone can be a multi-step process.

2. Sand the surface of the countertop with finer and finer grits of sand paper, removing the dust with clean water. Some craftsmen sand concrete countertops to an amazingly smooth, slick surface.

3. Once the concrete countertop has been sanded to the desired smoothness, it must be sealed with a penetrating sealer. Seal it in one direction, let dry (for several hours), then seal it in the other direction. Repeat the sealing process until the concrete doesn't absorb any more sealer.

4. When it is sealed, apply a coat of beeswax with a clean soft cloth, and buff it off.

The dangers of improperly finished concrete countertops are as much to the countertops themselves as they are to the users. Even the most perfectly finished concrete countertops will stain, and the sealing process is done to minimize this. Concrete that has only been cured and painted will probably not stay painted, and if they are rough and scratchy, they'll be a serious turn-off to future tenants.

The paint probably won't be too big a health issue as long as you put down cutting boards and don't put food directly on the countertop, but it's hard to say without knowing more.

Because concrete is porous, it will absorb liquids. Acidic liquids like juices and vinegar will create light spots, while cooking oils will leave dark spots. Setting unglazed ceramics on concrete counters will compete with the concrete for minerals, eventually leaching them out and leaving a residue.

If I were you, Chris, I would be more concerned about my damage deposit than anything. Even if you regularly clean off concrete countertops with warm, soapy water and a soft cloth, it's almost impossible to keep them from staining, and if your landlord isn't expecting this, he is in for a surprise the next time somebody moves out.

It's hard to say if your landlord is finishing your countertops improperly without photos, but it sounds like maybe he has cut some corners in his kitchen remodeling effort. While it probably won't represent a health hazard (except for perhaps scraping an elbow on one if it really is rough), they may not stand up to the realities of day-to-day living as well as your landlord is hoping.

For info on making non-dangerous concrete countertops, please see How to Make Concrete Countertops

Best regards,

Alan
Meet-Mr-Concrete.com
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