ᐅ Yellow stains on a white wall – can they be covered with white paint?

Hello, I hope you can help me.
My girlfriend and I recently moved into our first shared apartment. Since neither of us are big fans of yellowed, poorly applied textured wallpaper, we removed it, and her brother, who is a mason, applied a decorative plaster finish to the wall. Now to the problem: in some places, yellow stains are showing through the wall, but these mainly appear where there are wooden beams underneath. My brother-in-law suspects that the previous tenants smoked heavily in the living room (this is the only area affected), but none of us are certain. Is there a way to permanently hide these stains under white paint? The building is an older property. We still have several renovation tasks ahead and would prefer to avoid unnecessary steps in order not to get "stuck" on one room for no reason.

Hello Cutepie!!!

Well, I can't really tell what exactly those spots are, maybe they could be chipped off, but whether that makes sense now that everything is finished is something you need to decide.

You could isolate the remaining spots; one option would be to spray them with a stain blocker (to isolate), or the second option is to chip off the plaster and replaster.
Best regards.

There is a type of primer available at hardware stores called sealing primer that prevents stains such as nicotine from bleeding through. It is usually white but can be painted over without any issues. This should solve the problem.

Hello Joerg!!

A quick tip!
The so-called vapor barrier you bought from the home improvement store is actually the stain blocker I mentioned, which also comes in spray cans.
Best regards.

Sorry, I didn’t know that – I haven’t seen it in spray cans before, and I had a different idea of what a stain blocker was. I only know this product as a primer for problematic substrates.

Hello Joerg,
No problem, it wasn’t meant offensively, just for your information.
Best regards.