Is this white mold or 'efflorescence'? (photos)

newhomeowner-2009September 8, 2009

So my basement flooded a couple of weeks ago, and since then has been a bit damp. Suddenly a few days ago I see this white fuzzy stuff on the floor.

Thinking it's mold I immediately spray with hydrogen peroxide, wait ten minutes, scrub a bit and clean it up. Next day it came back.

Then I read that it might be something called "efflorescence salts." See

The pictures below show what I have. Any thoughts would be appreciated.

Here's how it looks from a distance:

Here's closeup No. 1:

And a closeup of another area, No. 2:

Any thoughts on this (and how to clean it up, if mold) would be appreciated.

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Hard to tell.

Looks like efflorescence.

But to be sure, pour a 1/2 ounce or so of straight chlorine bleach directly on the area, then wait 24 hours.

If the white disappears, it is likely mold.
If it doesn't, it is likely efflorescence.

If it is mold, all that is required to clean it is a 1:1 solution of bleach and water applied to the area.

You can remove (or ignore completely if you wish since it is harmless) efflorescence with muriatic or other mild acid dilutions.

    Bookmark   September 8, 2009 at 9:32PM
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Good idea. Just did, and I'll see what happens.

One thing I forgot to mention is that it has no moldy smell.

    Bookmark   September 8, 2009 at 10:11PM
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I dropped some bleach onto the floor (probably more than a half ounce) and it did seem to kill whatever was there. I think it's safest to treat whatever it is as mold. I notice that a couple of sheds on my property also developed a white moldy substance in water leaks, but the texture was totally different.

    Bookmark   September 11, 2009 at 10:26AM
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