Paint powdering off around inglenook - why?

[Nicbob101]

Hi there,

We've recently moved in to an old property and want to give some of the interior a freshen up with paint.

One particular area in need is the interior stone surround of the fire place, within which there is a gas inglenook.

The stone surround interior has been painted white inside and has patches which are going yellowey brown presumed this is due to heat? It looks like it's had some kind of rough plastering; possibly some special effect doesn't look like normal plaster as it's rough and bumpy ?!?

I was just about to start washing it down to prep for painting when I took a closer look and it looks like whatever paint or plaster is there is powdering off - it's like patches of powder stuck to the paint that flake off if you run a finger over it. I wondered if it has lime or something in it as it's an old property although the fireplace is a more recent addition?

Can anyone help tell me:
a) what this is caused by
b) if it's safe to clean off
c) how best to remedy - will cleaning [can I use water on it?] and re-painting work or does it need plastering or special paint or ....a professional?

Help

Thanks