Ceiling bumps / lines

[k.enright]

Hi there,
We bought a flat a few months ago and have noticed these lines on our livingroom ceiling coming from the chimney breast (not in use). They are mostly hard and firm to the touch, presumably filled cracks or joins in plaster? However they aren't running straight so perhaps not joins. How would we go about sorting them? Or does anyone know if they would be a cause for concern? Any not firm areas feel like air under paint/paper.

Thank you kindly

 

[Wayners]

Lath and plaster ceiling or plasterboard?

 

[k.enright]

It's plasterboard. They are 1950's council flats.
Thanks

 

[opps]

I have never seen plasterboard do that before. Cracks are typically straight lines.

Is it possible that they are concrete ceilings?

You could sand them back with a random orbital sander (ideally connected to a dust extractor). Alternatively, you could have then reskimmed.

 

[k.enright]

ok thank you. Yes they must be concrete really as it's in between floors of a apartment building. But it says on our home buyers survey "Most of the ceilings seem to be made of modern plasterboard, finished with a skim coat of plaster and lined or painted with emulsion."