Fireplace

Hi guys,
I have an interesting issue and am unsure what to do.
A few years back we had our 1930s house fireplace opened up, lined a hearth made and a log burner installed.
Earlier this year I noticed the boards at the bottom were all bowed and pushed out of shape, as I knew we were going to redecorate I removed the burner and the lining boards.
The cavity behind was chock full of salts.

Before we finish decorating I'd like to deal with this and re-instate the burner.
The bricks are quite tatty so I don't think leaving them on show would be a solution unfortunately. Are there suitable boards that can deal with the salts and the heat? or can I apply a paint/sealer to the walls and then re fire board?

Can anyone help?

Thanks.

Iain80, good evening.

Any chance of posting some images? may assist?

What type of boards were they?

How wide was the cavity between boards and brickwork?

What colour was the build up of "salts"? and did / does the brick have a layer of mortar in places adhering to it?

Is there a gap between the chimney flue and the back of the boarding?

Ken

I can try and get a couple of pictures when I get home.
I don't know the type of boards, they were like plasterboard and dabbed straight to the bare brick.
The cavity behind wasn't a "cavity" as such merely a few small spaces were the underlying brick kind of meander about a bit, but the build up was quite substantial.
The salts were white.

Yes there is a gap, it has a top flue which is probably around 150/200mm from the rear wall.

Thanks.