John Anderton wrote in message . ..
Having just removed a modern false chimney breast I've discovered the
probable reason for putting it in in the first place. Namely, the
original chimney breast is heavily stained with wood and coal tar
which has worked it's way through the brickwork.

I solved the underlying problem about ten years ago by installing a
multi-fuel stove with a nice thick stainless steel chimney liner which
goes right to the top of the chimney but what is the best way of
sealing the stained plaster so I can paint the chimney breast without
worrying that the stain will come through ?

I'm currently considering that good old staple, PVA. Would a nice
thick coat of that be sufficient or do I need something more
substantial ?

What about stainblock paint? I've never used it on smoke/tar stains
like you have, but it's certainly worked well for me with other stains

David