insulate before curing

[david s]

Re: insulate before curing

Fast drying render is prone to cracking.This can be alleviated by keeping it moist. It takes 28 days to get to full strength. Check this link for advice from the experts.
Cement Render | Texture Coatings | Solid Plastering

[brickie in oz]

Re: insulate before curing

True but the relevance for added strength is not needed in an oven.

Edit:
I work with Portland cement day in day out, when the temp gauge hits 30 to 40c the brickwork Ive laid is as hard a stone within a week with no babying of the mortar.

[david s]

Re: insulate before curing

It applies to anything made with Portland cement.

[brickie in oz]

Re: insulate before curing

you should keep the stucco damp for a week to increase its strength,

The idea of keeping cement based products damp applies to hi end concrete structures, like bridges, dams, hi rise buildings etc.

I cant see the relevance to a backyard oven?

[david s]

Re: insulate before curing

"wait one week after the oven is completed."

I think this means after the brick dome is completed. Assuming the one week gives the mortar a chance to cure and also using the weather to remove some of the moisture before driving it out with fire. Personally I believe that waiting even longer is probably better given that the homebrew contains quite a bit of lime which slows the curing process down. The trouble is that when you get to this stage you start getting excited and want to push on and get it finished.

[david s]

Re: insulate before curing

"I was hoping to put on the insulation (3 x one inch inslulating blanket) and then put on the first coat of stucco. This would bring me to 5 days or so after the brick work is complete, then I would start the oven cure for 5 days while the first coat of stucco also cures. Then I could put on the top coat of stucco and a few more days of curing and then pizza time."

Given that you should keep the stucco damp for a week to increase its strength, I think it is probably better to cure the oven before doing the stucco. Any build up of steam in the insulation layer can produce enough pressure to crack the outer shell (water increases by 1000 times when it turns to steam). For an igloo I think it"s best to cure after placing the blanket then do the outer shell and keep it damp by wrapping in plastic for a week, before proceeding with more fires. But there is more than one way to skin a cat and other no doubt others will chime in with their method.

[waynespizzaworld]

On my first oven I did the slow cure before I put the insulation on. I have noticed on my updated instructions for the build of the Pompeii that it is recommended to wait one week after the oven is completed.

Does this mean after insulation is on and also stucco?

I was hoping to put on the insulation (3 x one inch inslulating blanket) and then put on the first coat of stucco. This would bring me to 5 days or so after the brick work is complete, then I would start the oven cure for 5 days while the first coat of stucco also cures. Then I could put on the top coat of stucco and a few more days of curing and then pizza time.

Does this sound like a reasonable approach?

Looking at my pictures from my last build I see I cured before insulation was put in place and all was well. No big cracks after about 3 years of use. I am guessing the instructions have changed since the pdf files were first sent out but maybe I just did not read into them properly.

Thanks Wayne