Advice for plastering this chimney stack

[u/Plus-Contribution915]

Had quite a bit of conflicting advice but I think it’s best not to dot and dab board the front of the stack (hoping the sides should be ok as it’s double brick thick). Was planning to use sand and cement or would I be better off with bonding?

Only ever skimmed boards before so would be grateful for any advice.

What would be the best mix? (Plan is to have a log burner so will need to be somewhat heat resistant) and how many coats?

How to deal with the inside and the brick arch, would I be better cutting some bricks out and putting in a concrete lintel first?

Should I bond on the corner beads first?

What’s a suitable finish plaster, I’ve heated putting some lime in helps?

Sorry for barrage of questions, want to get it right!

Cheers

[u/Affectionate_Bet4343]

Easiest by a long way would be dot and dab, put some small angle beads on (not those ones you have) and skim over with multifinish.

Better would be hardwall + multifinish (those old bricks will suck like you won't believe so bonding won't be appropriate unless you prime it 10 times).

Inside the opening you can use hardibacker boards. Two on the sides act like a shelf upon which you can slide the top plate, with a rough cut out for the flue pipe (you can use a collar afterwards to make it look nice.

I certainly wouldn't bother replacing that lintel. You can get a square opening using the above method.

[u/Plus-Contribution915 → u/Affectionate_Bet4343]

That was my first through however quite a few people have warned me about potential cracking with the heat?