Any plasterers or decorating experts?

[Justwingingit2005]

Hey
We had a new bathroom fitted 6 months ago.
Had ceiling skimmed end of Aug.
The ceiling has been bubbling since Sept time.
I'm going to get the plasterer back but any ideas why?
Never had this before.

Could it be trapped moisture? Was it painted too soon after being skimmed and so didn't dry out properly?

We don't know as we were on hols when decorator did it. We left a key with someone and got home and it was done.
Weve has various walls skimmed etc and never had this before!

How long was the plaster left to dry before painting?
What prep was done to the plaster before painting?

Either painted when plaster was not completely dry, or they didn't prep the plaster first (by using a watered down paint layer as a base coat).