Vermiculite after curing?

[phippsj]

I am just about done with the dome, so I am now starting to think through the final process. I will be curing with vermiculite all around the exterior of the oven. However, I was planning on curing the oven prior to adding the exterior insulation (to be able to see cracks and correct if necessary).

When I add the external vermiculite, will moisture get back in? Do I essentially need to cure the oven twice in that case?

Thanks!

[dmun]

Yes, vermiculite absorbs LOTS of water. It's why it's used as a soil conditioner in agricultural use. Once you pile on your vermiculite concrete, it will be wet all over again.

This doesn't apply if you're building an enclosure, and pouring the vermiculite in loose.

[phippsj]

I am building an enclosure. Would pouring in loose vermiculite have the same thermal benefits as the vermiculite/cement combination? Six inches of loose vermiculite and I am good?

[Laku]

Originally Posted by phippsj

Would pouring in loose vermiculite have the same thermal benefits as the vermiculite/cement combination?

Probably better than vermicrete as it doesn't have the binding cement to transfer what small amount of heat it transfers.

[Bambalorna]

Originally Posted by dmun

This doesn't apply if you're building an enclosure, and pouring the vermiculite in loose.

I'm building an enclosure and using 3 inches of insulation-blanket around the oven. A neighbor from southern France says they fill the enclosure with sand. Is vermiculite much better than sand?

[Laku]

Originally Posted by Bambalorna

Is vermiculite much better than sand?

Yes. Sand is more an addition to oven mass than real insulation.

[Neil2]

One advantage of a weak vermiculite/cement (12:1) mix for the dome insulation that it will eliminate loose vermiculite from seeping or blowing out of joints in your enclosure. (In any case, your enclosure should be well vented to keep the insulation dry.)

[Bambalorna]

Originally Posted by Laku

Yes. Sand is more an addition to oven mass than real insulation.

Thank you Laku, much appreciated