There was peeling and bubbling paint in the area (bottom right) where the brownish stains are in the picture. wall stain

That wall has been scraped, sanded and skim coated. I think the wall is plaster.

What would cause that brown stain?

There is plumbing behind that wall. The shower head is in the other side of the wall ( a foot or so above that stain and maybe a foot to the left)

2 Answers 2


Moisture. Given the sequence of events resulting in the appearance of the brown spots and an obvious source of moisture, from the piping, one can rule out "grease", "tar", "solvents", "oils", and etc. Whatever caused the previous paint to "bubble and peel" is continuing to impact this area.


It looks like there was a stain and more likely water damage under it. You need to let that dry out before a skim coat. Also you could have mold.

  • If wasn't wet when we put the skim coat on.
    – milesmeow
    Jan 8, 2017 at 10:25
  • Not on the surface you mean.
    – DMoore
    Jan 9, 2017 at 4:31
  • The wall was not wet when the skim coat was applied.
    – milesmeow
    Jan 9, 2017 at 7:42

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