A few months back, I screwed up. I had a bucket of paint left over after my place was professionally repainted a few years back and decided to touch the place up by painting over some stains on the wall. I used a roller to paint approximately 3 m2 altogether.

Now there were several brown-black stains on the surface of the paint and it did smell funny (by which I mean slightly rancid), but it did not enter my mind that mould could grow in a bucket of paint - I just assumed the parts of the paint had separated and so I stirred the paint. The paint worked seemingly just fine after this and there is no discoloration.

After painting the wall (which is a concrete wall), it smelled a bit of what I now realise was mould, for about 30 minutes to an hour. After that however, there is no smell and no visible hint of mould on the wall.

I only now realised, after reading up, that indeed mould can grow in paint and that I accidentally painted with mouldy paint...

Should I still be worried about mould growing underneath or so? The apartment is usually dry as the desert and I have had no problems, there is no smell or discoloration whatsoever. Still...

  • Did you thoroughly scrub away the staining material first, or jus bury it under paint? Mold aside, the latter will trigger early paint failure. It may be best to scrub all of it away, use the remaining "moldy" paint to paint some "chips" to take into the paint store to get a match, and get new paint. Nov 17, 2020 at 21:00
  • Also, an old friend has advice on disposal of old, unusable paint without environmental issues: Paint something you don't want... then, throw it away. Nov 17, 2020 at 21:02
  • Maybe I was unclear... the stains on the wall were not mould stains but light liquid spill stains which were scrubbed. The only mould was in the actual paint I used. Unfortunately I do not have the money to repaint the entire apartment, which would be the only way to get a matching colour. Nov 17, 2020 at 21:42

1 Answer 1


If the wall isn't subjected to regular moisture there's no reason to think that the mold will keep growing. Mold spores are everywhere already. Most of them are harmless.

To deal with the stains, use a stain-blocking primer. Then paint again.

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