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paint over sealant?

by helen
(san diego california)

Q. I have used muriatic acid twice to etch my 15 year old interior concrete floor. It hissed and bubbled (about 1 part acid to 10 water) and I left it on for 20 minutes after scrubbing it with a nylon brush. I flushed it with water and baking soda and more water to neutralize.

The next day I painted 2 coats acrylic concrete stain as a base. About 18 hours after the second coat I put some tape in an inconspicuous area because I was planning to make some faux "tiles" by sponge painting. When I pulled the tape up, the paint came with it.

Did I not wait long enough? Did I not remove the sealant when I used the muriatic acid? Is my project hopeless? Could I save it by top-coating with a sealer?

A. If there was a sealer on the floor to start with, then the problem is the sealer is still there. Acid will not etch away the sealer. It can still bubble and etch the concrete because some of the acid is reaching the bare concrete, but the sealer remains. I'm guessing there are areas with sealer and other areas with very little or no sealer at all. If it bubbled and hissed as much as you say, then most of the floor is probably OK. My suggestion is to go ahead and put a strong clearcoat(epoxy or urethane) over all of it. Keep some stain around in case you have to do spot repairs down the road.