What's going on with my wall 😳

[nomchangio]

We painted a wall in our bedroom in February. The wall was a mid grey and we painted over it with darker grey matt emulsion. It took 3 coats.

In the past couple of months, marks have started to show, which are getting bigger and more noticeable. It's areas where the previous wall was getting a bit grubby. So, while I assume something has reacted with the new paint, why did it take so long to appear, and why does it seem to be white and almost powdery, rather than greasy marks? And why hasn't this happened before? And how do we rectify it?

Photo attached of one area.

I can’t offer any suggestions as to what’s caused it unfortunately but using this then repainting would maybe sort it:
www.toolstation.com/zinsser-cover-stain-primer-paint/p56164

We used this on some bad water stains from a leak and it worked a treat.

Do any of them look like The Virgin Mary?

Is it an outside wall?

@tupperwaretowers

Is it an outside wall?

No, it's the wall between our house and next door

Looks like you painted over gloss

Baffling. You can sort of see brush work, To me it’s almost like something was painted on before tester wise and then painted over.

Flourescence?

Sorry o meant efflorescence!!

Definitely didn't paint over gloss.

Yep it's like a tester area or something. But there are similar marks literally all over the wall, it's so weird. The fact they appeared months later too.
I'll add another photo 😀

Another image

@gardeninggirl68

Sorry o meant efflorescence!!

Hmm interesting. Thanks. We do have this on exterior walls but didn't know it could affect interior too. 🤔

@WeeM

I can’t offer any suggestions as to what’s caused it unfortunately but using this then repainting would maybe sort it: www.toolstation.com/zinsser-cover-stain-primer-paint/p56164

We used this on some bad water stains from a leak and it worked a treat.

Thank you. Yes will definitely use this next time. Hopefully we won't need to do much to prepare or rectify the issue first. Good to have one recommended too. Thanks 💕

Do any of them look like The Virgin Mary?