Gritty paint removal..

[Coaster]

Hello,
mate of mine in council house, has some sort of gritty textured paint that was painted directly onto the plaster in the bathroom.
She's tried paining over it but where the surface gets damp/wet the paint comes straight off.
She was thinking of putting waterproff wallpaper over it but may just make it look worse.
She ha tried using a sander but to no avail.

Is there an easy(ish) way to get this stuff off?

 

[Nige F]

try a steamer used carefully - ie. so it doesn`t heat the plaster and blow it