Can I remove arch form before mortar is dry?

[Jfeldman]

[Gulf]

Imo if it were home brew mortar, if there are wedges under the arch form that can be removed to allow it be lowered gently, and there is buttressing on the soldier course, it should be ok to lower the form for cleaning after an hour or so. But, I can't see enough in the pic to be sure about all of that.

[Jfeldman]

The soldier bricks are supported from behind by the layer of concrete I used to fill between the exterior bricks and the concrete block base.

[Jfeldman]

I almost forgot, the mortar is called Derby 3000. It is made by Louisville fire brick works here in KY. There are no wedges under the forms, just large bricks.

[Gulf]

I've never used air set refractory mortar. My understanding is that it takes about 48 to 72 hours for it to set. (A much longer time than homebrew which is about an hour imo). And, that it takes high heat to really cure it to the point that water won't dissolve it. Maybe someone else will weigh in here, but I think that I would take that into consideration. It sounds like your soldier courses can't kick out on you so the arch should be fine if you can be careful letting the arch form down. I am sure that you know by now that the concrete behind the soldier courses is going to suck a lot of heat out of your oven.

[valentin]

If you used a wedge bricks, the arch can be removed immediately after laying has been completed. But since you are using the rectangular bricks need to put the squeeze on a full curing solution.

[Jfeldman]

I've never used air set refractory mortar. My understanding is that it takes about 48 to 72 hours for it to set. (A much longer time than homebrew which is about an hour imo). And, that it takes high heat to really cure it to the point that water won't dissolve it. Maybe someone else will weigh in here, but I think that I would take that into consideration. It sounds like your soldier courses can't kick out on you so the arch should be fine if you can be careful letting the arch form down. I am sure that you know by now that the concrete behind the soldier courses is going to suck a lot of heat out of your oven.

The concrete behind my soldier bricks is a 5:1 vermiculite/concrete mix.

[Jfeldman]

[Jfeldman]

I took the forms out today and they didn't fall!