A.Ed McPartland, a Wellfleet, Mass., builder, replies: Glitsa is a catalyzed varnish designed for wood floors, so it’s not surprising that it didn’t work well on concrete. To remove it, apply a chemical paint stripper, cover it with wax paper for about 15 minutes to prevent drying, then suck it up with a wet vac. Be very thorough with this process. Get down on your hands and knees and eyeball the floor with the aid of a strong light, to pick up any remnant "flash." Make sure the concrete is completely sponge-clean and dry before refinishing.
I don’t use urethane because it doesn’t hold up to wear. I have acid-washed concrete in the past but haven’t been satisfied with the result, and I don’t think it’s absolutely necessary.
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