ᐅ Question for experts regarding stains after painting work

Hello everyone,

I have a question that I, as a non-professional in construction, cannot answer. About three weeks ago, I painted a wall. After being on vacation for the last two weeks, I noticed that dark spots have appeared on the wall. Honestly, I can’t explain this, as these spots were not visible right after the painting and after the wall had dried.

Can anyone imagine what might have caused these spots? Would repainting fix the issue, or is this a more serious problem?

It looks like it is exactly where the slot for the electrical wiring is located. Possibly, it was filled with a filler compound that is not compatible with your paint. Who did the work, and was it done recently?

Tolentino schrieb:

It looks like it’s exactly where the slot for the electrical wiring is. Maybe it was filled with a filler that isn’t compatible with your paint.
Who did the work, and was it done recently?

I moved into my apartment last year. I suspect the previous tenant’s renovation took place early last year. However, these discolorations were not visible before. The stains seem to have formed after drying. Could this be caused by moisture? It also seems suspicious that the stains follow the cable ducts.

Rafael619 schrieb:

that the stains run near the cable conduits.

Cable run to the light switch, then to the outlet, then left to the next junction box.
Did you prime the surface beforehand?

ypg schrieb:

Line to the light switch, then to the outlet, then left to the next junction box.
Did you prime the surface beforehand?

I didn’t. Is it necessary to prime over an existing paint layer? Until now, I assumed priming is only required on fresh plaster. When drying, the wall didn’t show any stains. It was only after several weeks that these streaks appeared. Could it be that moisture penetrated through the cable channels?

For now, I repainted the wall. I’ll wait and see if there are any changes.

Thanks in advance for the advice.