What to use to cover soot/tar from removed Chimney breast.

[Gazzataf60]

Hi all,

I have just removed the chimney in the house and obviously it was used so there are the black soot /tar marks from use in both rooms.
My question is, what is the best way to avoid problems from the nitrates and hygroscopic salts etc from coming through the finished plastered wall.

Any advise will be grateful.
Thanks

 

[curium]

I am not a plasterer but I was watching YouTube for advice on preparing my fireplace for a stove and a plasterer I watched used a wire brush to remove as much shot as he could and then painted the area with blackjack. While the blackjack was wet he dashed sharp sand on it to provide a mechanical key.

Once dry, he used a brush to remove any loose sand.

He then rendered with a 6:1:1 mix of sand, cement and lime.

Like I said, I’m not a plasterer. If I find the link to the video I’ll post it for you.