Major mortar issue inside dome

[pacman74]

So my brother-in-law said he had a faster way I can build a dome. He cut out a piece of fiber glass and put it up towards the dome. He set all the bricks but he out mortar on the inside, and when I removed the fiber glass, I have a think layer of mortar? Do I have to start all over? Do I need to chisel this off? Or can I leave it?

not sure what to do?

[Giovanni Rossi]

I believe stuff like this happens when you watch an on-line video without fully understanding the process. To use a fiberglass form like this it needs to match the arc of your specific dome. Had you dropped the form when the mortar was set and before if fully hardened, you may have been able to clean most of it. That's supposing the joints were tight enough to provide proper structure. Refractory mortar is a different animal from refractory castable. I would think it's going to spall over time, but I'll let the more experienced builders weigh in. No turkey for brother-in-law!