How do I need to maintain this concrete countertop?
June 23, 2020 4:48 AM   Subscribe

Over a year ago, we moved into a house with a mottled, matte concrete countertop, probably sealed with penetrating sealer. We've just been cleaning it with vinegar/water or with general purpose cleaning sprays. It's developing wear but so far seems okay. But I see recommendations online to periodically wax and seal concrete countertops. What's really necessary and why?

Here are photos. You can tell the areas of wear, which have developed in the time since we moved in. So far, they don't bother me, and I'm open to considering it character if I should. The surface doesn't darken when we drip water on it, though an area that tends to stay wet under our soap pump has darkened (as seen in the last photo). The seller said the counter was sealed, and he left behind an open bottle of Seal-Once Advanced Multi-Surface Waterproofer, which I bet is what he used.

Online, I see recommendations that we should wax it with beeswax or carnauba wax once a week, or once a month, or every few months, depending on the source. What's necessary? What difference will it make if I wax it or if I never do? Is there a sign to look for that shows it's time to wax it? Can I just buy any beeswax or carnauba wax and rub it on and off with rags?

What about sealing it again? Online it says we should do that too, once every few months, or every year, or every few years, depending on the source. But on the Seal-Once bottle, it says that if dripped water doesn't soak into the counter, we'd have to strip it before reapplying. That doesn't sound like something the typical homeowner routinely does. (And it IS called Seal-ONCE...) Do I ever have to (strip and?) re-seal it? When? How?
posted by daisyace to Home & Garden (6 answers total) 3 users marked this as a favorite
This website indicates that concrete countertops are prone to staining: "While counters made from cement will last for years, they are vulnerable to stains. You’ll need to regularly reapply sealer and wax to protect the surface and be sure to clean up spills and messes right away."
posted by hepta at 6:15 AM on June 23, 2020

I'm interested in this question, too, as years ago I managed a coffeehouse that got concrete countertops in a remodel. After a couple of weeks of some kind of curing/finishing, the countertops had beautiful satin-type finish and were largely impervious to anything except acids. We had a juicing machine that leaked and when it was moved the counter underneath was pitted and the finish gone. I've always wanted to keep in mind using concrete as a DIY for my dream home kitchen.
I recalled that the builders said something about 'water conditioning' the bare concrete, don't know what that means but I did a search and found this resource from, concrete countertop sealers, .
There is also this personal account with info on testing various foods that stain concrete. TLDR; this person is really upset that concrete stains and won't remain pristine. I don't get that sense from your question, but there is some information to be gotten from their testing and end result.
Best of luck, and if you feel inclined please post a follow up with what you used and how it worked out.
posted by winesong at 9:50 AM on June 23, 2020 [2 favorites]

Vinegar is absolutely the wrong cleaner for any kind of polished concrete because it will dissolve an unprotected surface within minutes.

I suspect the "wear" you're seeing is chemical weathering from the vinegar.
posted by jamjam at 2:09 PM on June 23, 2020 [6 favorites]

I scrolled down to say what jamjam wrote. Concrete is just rocks of various sizes glued together with Portland cement. Anything acidic will attack the Portland cement.
posted by jon1270 at 4:58 PM on June 23, 2020

Yes, vinegar will slowly dissolve your concrete countertop (though an astonishing number of people will say to use it to clean concrete!). Basically it dissolve CaCO3 and dulls the surface by creating tiny pits all over the concrete and changing it's pH, which can affect any previous sealer as well. My feeling is that you may want to call in a professional in order to refinish the concrete to have a consistent color/surface before sealing. If you just wax or seal on your own you may just end up preserving the variation in appearance that currently exists.
posted by oneirodynia at 5:56 PM on June 23, 2020

Response by poster: I'll be sure not to use vinegar anymore. Luckily, I don't think it's done any damage yet: the wear is the part we use most, but the couple/few times that I've cleaned with vinegar, it was an even spray all over a cleared-off counter. Also, diluted and quickly wiped back up. Also not under the toaster oven (I admit it, I'm not that thorough), which I just checked looks the same as the area that I do wipe, just in front of it. Anyway, point taken, thanks.
posted by daisyace at 6:52 PM on June 23, 2020

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