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Question DetailsAsked on 1/7/2017

can i apply direct flame to a molded cement wall

I have a masonry structure with black mold in the kitchen ceiling of the first floor only.
I would like to apply localized flame from a gas/propane torch to burn it off then follow the recommended cleaning with bleach followed by oil based primer ahead of the painting.

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2 Answers


I guess you could, being careful to keep it to just enough to burn the mold, not hot enough to start debonding the water that makes it concrete and starting spalling (concrete starts breaking down at about 600-1000 degrees F depending on constituents, and propane torch is about 2500-3000 degrees - so VERY easy to cause surface overheating and spalling. Naw - I would not do it that way - not only from the safety standpoint (fire risk and dangerous combustion products plus possible damage to embedded utility runs in the overhead concrete floor), but normal propane gas is not totally oil free so it could cause oil staining which could come through the paint. Plus I would bet you could get a NASTY smell throughout the house which you might never get rid of.

I would kill it with good pure bleach or mildewcide double treatment (so in the removal phase you are not spreading mold spores all over), then with appropriate personal protective gear scrub clean using aggressive abrasive bleach-based cleaner, then normal post-mold removal prep and priming and painting from there. Course, you will need super protection of kitchen cabinets and flooring and such if the room is not gutted for a major remodel.

Note I agree with the oil-based mildew-resistant priming (oil based Kilz or such) because the water based ones seem to be useless, but bear in mind unless going to use oil-based ceiling paint as well (per manufacturer prep and overcoating instructions), you would need to do abrasive surface prep and/or repriming of THAT oil primed surface before painting with latex or acrylic latex or it will not stick properly. I also add an additional dose of mildewcide - (CrudKutter is the brand I use, or something close to that - used to be available everywhere, now I get mind through Amazon) in the can of primer and all kitchen and bath paints to increase their mold/mildew resistance.

Answered 3 years ago by LCD



This is Erick in Member Care. Thanks for your interest in Angie's List!

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Answered 3 years ago by Member Services

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