air bubbles in the bathroom ceiling

[Doran]

Over the past year or so, I've started to get airbubbles that only appear when its shower/bath time.

What's the best route to fix this.. (and what's the cause?)
Junior DIY'er here so any advice appreciated.

I'm guessing sand the entire ceiling to remove the paint.
Seal it? (if so, what with?)
and repaint.

Any other things to think of in this situation?
Cheers

 

[sparkwright]

Scrape off all the loose paint, fill to eliminate the edges left, sand, spot prime bare plaster and filler with diluted matt emulsion, re-paint the whole ceiling.

 

[Doran]

Thanks.
When you say dilute emulsion.. 50/50?

 

[sparkwright]

Seems to vary, probably not that much water. it should say on the can... But of course it may not... ...

 

[Doran]

Lol thanks nicely vague lol