The paint in our kitchen is failing. The walls are plaster. Initially we thought the paint failed because the plaster cracked and was shifting. We repaired the plaster, scraped all lose paint, cleaned, primed and painted. That paint lasted for about 6 months and then started to fail. We did the process again and the paint lasted for 2 years and then started to fail again. Eventually the paint starts to scale and bubble and separate from the wall. We just got done scraping a majority of the loose bits off (mostly because we were tired of paint falling down in our cooking area). I'm confused by what I see. Here are some pictures:
The above picture is the ceiling. There appears to be 3 layers here. The paint, a thin brittle layer, and the plaster. What is this thin brittle layer? I assume since it is brittle I would need to scrape it completely off to be able to prime and paint over the plaster. Is that correct?
Some walls also have dark spots behind the paint. Is that mold? There are more places without visible dark spots like this that are failing than there are. Would I be able to clean, prime and paint this, or is there something else fundamentally wrong here?
The main question we have is what steps do we need to take to successfully repaint the walls and have them smooth and the paint not fail. Is this possible, or should we look into ripping them out and replacing with drywall? That seems like overkill and far off in our budget so not sure what my options are.