Thanks for the info. These guys made a slurry mortar after the slab was assembled on the floor. They did flush out the mortar with the face of the bricks, with the watered down mortarI am pretty sure it's not fire clay, the mortar I have seen them use is sand mix. But with that said I am unaware of what fire clay is. Goggle may give me that answer.
I also am unaware of what raked means to a mason, and I am sure goggle doesn't have that answer.
This will help you understand the nuances of laying fire brick. Please not the extremely tight joints,one could barely place a playing card between them.The tight joints and 'special" mortar lends itself to many years of service life.
Also,a raked joint is when the mortar is recessed beyond the face of the brick. Unless my eyes deceive me,that is what the masons did on the subject firebox. Not really the preferred method by most trade standards.
I guess there was shrinking of the mortar? That sounds logical to me.
I would like to hear from you, just love learning.
The most efficient way of doing it the way they did it is to grout bag the joints, unfortunately you can’t get a code compliant mortar using that method.
Looks good, A plus for execution, but I’d rather have a lip here or there with a 2000 degree rated mortar.
Things to be aware of before you start doing the bowing thing to the masons...