Plastering Firebox

[emailogram]

Hello,


Our Quaker Meeting House has a fireplace which has been spalling the coating over the stone. Below are images.
We'd like to chisel off the cement and replace a coating over the stones, in the rear.
I have a done a little plastering with Hawk and Trowel and thought we could do this ourselves since it is cosmetic (nothing combustible behind).
What type of cement should we use? I saw a fire cement / mortar which looks like it is for firebrick and small patches and refractory cement.
Would we be able to use one of these?
If we do, should we keep it 3/8" or less? If so, can we build out areas which spalled deeper?





The building is 201 years old. The fireplace was rebuilt in 1999-2000 and the solid flue was poured in 2005.

Thank you.

 

[webby3650]

I don’t know of any product that would hold up the abuse a firebox takes. What’s the reason for the plaster anyway? Is there firebrick behind it?

 

[emailogram]

There is stone behind. I believe it is sandstone like the rest of the Meeting House.