What is this growth?

[Neal Lewis]

There is a growth in a couple of closets in this house, a bilevel in good condition with no leakage or moisture issues. The closets haven't been painted in a long, long time, with solid doors.

It almost looks like nicotine staining to me, but I didn't smell anything.

Any thoughts what it is? Thanks

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[Jim Morrison]

Looks like mold growth on the exterior walls of an unheated closet to me.

[John Kogel]

It appears to be almost certainly mold, one of the hundreds of varieties. Jim is right, a cold corner allows moisture from the room, people breathing and respiring, to condense on the wall.

Nicotine stains would be high on the wall and on the ceiling, following the path of a smoke cloud.

Here's a couple of mould patterns I've collected. Fascinating stuff.

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[Erby]

Lack of air circulation + condensation = mold growth.

[ghentjr]

Mold. Caused by black stockings used often but never laundered.

[John Kogel]

Mold. Caused by black stockings used often but never laundered.

I saw them and I saw the comment "but I didn't smell anything", and then I wisely chose to keep a lid on it. []