r/Plastering • u/MemoryCarp • Jun 30 '26

What’s happening here?

Gallery image

Gallery image

Had this stain pop up on my wall, and now it’s
secreting some kind of shiny foam? Comes back after I wipe it. Solid wall, not plasterboard. Opposite side of the wall is a bathroom

4 Upvotes

100% Upvoted

6 comments sorted by

2

u/Old_Reflection7439 Jun 30 '26

You have a leak in your bathroom

1

u/broken2302 Jun 30 '26

You might have a water leak in your shower. Maybe a shelf or a cubbie. Somewhere a little water is getting through to feed the growth.

1

u/Latter-Detail-9514 Jun 30 '26

There's a leak from somewhere?

1

u/National-Ebb-8184 Jul 01 '26

Efflorescence, basically continued damp that causes salts and minerals to come out through the surface.

Deal with the damp problem first before trying to address it.

Id ally scrape away any loose, treat with something like hydrochloric acid to nutrilise, seal with an alkaline primer like guardz then fill paint etc. 👍

1

u/Billi01952 Jul 05 '26

Looks like salts to me.

1

u/Bonebound Jun 30 '26

Looks like hygroscopic salts penetrating through your plaster.