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jeff 01-09-2008 07:33 AM

Quest. re Aluminium inter layers.
I read on FB tonight that Al should not be used amidst vermiculite in dome insulation as it inhibits water vapour transfer.
My thought is that the temperatures at which these ovens operate will prohibit significant water vapour ingress in the first instance.

I would love to hear your experiences/comments.

My brick shell is covered with 2" [see, I'm learning, Cousins: 50mm indeed!!] of concrete/sawdust admixture.Next comes Al insulating sheets, to be followed by 25mm ceramic blanket. In turn, this will be encased by roughly 3" of vermiculite, contained in Al ceiling insulation batts. (Photos to follow, tru).
The final shell wiil grade from light-weight concrete (probably vermiculite based, but possibly straw/sawdust), to high-strength concrete.
Final cosmetic layer remains undecided: advice welcome, eh.

So place your bets Fellers: Pass or Fail?
Tickets are a cent a piece: buy up big and raise yer chances!!! hahaha.

I'll post my opinion after the first test, although a definitive result may not emerge within thirty years. And I sure as hell won't be here to run that revue, eh.

Stay good you mob.

dmun 01-09-2008 12:02 PM

Re: Quest. re Aluminium inter layers.
My bet? It'll be fine. I don't think the aluminum will help, but I don't think the water vapor retention issue is significant once the oven dries out from construction.

In house insulation the vapor barrier is there because the interior is more humid than the exterior, and it keeps the insulation dry. Once you are above 212f (100c) retained humidity is about zero. Any H2O from the fire or dough is quickly exhausted up the chimney.

jeff 01-11-2008 04:58 AM

Re: Quest. re Aluminium inter layers.
Thanks Dmun.
One post - One reply.
Quality beats quantity most days, eh.

So all, (bar the enclosing dome), is done. Ended up with 75% of surface area having 2" blanket coverage. (Bought a 7600 roll [what's that? 25' maybe? ]of 1"; put on a layer of loose vermiculite to fill the gaps. Vermiculite 'tiles' over that, more loose fill, cover it all with foil, and lay on a light scratch coat of "stuff"* to hold it all in place and provide a key for the final shell.
Warm (min 22 celcius) and raining here at present -perfect curing weather for concrete.
Tomorrow or the next day should see the last of the functional bits done 'n dusted; then the aesthetics: yuk! I lack imagination, please help.
* cement:lime:sawdust:brickies loam - 1:1:4:2. [approx, hahaha, so who cares?]. jh.

dmun 01-11-2008 08:16 AM

Re: Quest. re Aluminium inter layers.

[approx, hahaha, so who cares?]
No, really, we like to hear about this stuff. I wouldn't recommend anyone make mortar out of sawdust, but if you do, we want to hear how it works. That's after all how they make insulating firebrick, by mixing sawdust with refractory clay before firing.

So a couple of questions. What's brickie loam? Loam means topsoil here in the US. And what are vermiculite tiles? Is that compressed vermiculite board that used to be used for soldering pads? Got a picture or a data sheet link?

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