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buckeye 04-15-2008 07:15 AM

Moldit-D and Transpiration
I'm a newbie to the forum and midway through installation of a Valoriani 110 cm modular. I didn't get it from CA so don't have access to their forum...I have not been able to find ref-mix locally and shipping costs being what they are, I've been looking for an equivalent to add an inch to the dome for greater thermal mass. I plan to do some extended cooking...I found Moldit-D locally and the specs for elemental content are very close to ref-mix. Does anyone have experience with this material? OK to cover the dome with it?

A different question on vents for the loose fill chamber...I plan to use perlite and cover the upper chamber with flat stone/mortar covering. The instructions that came with the oven state (in large letters) that openings must be left for transpiration. Design layout and installation photos on the CA site show no provision for this so I e-mailed Italy and the response was that the openings are definitely required-presumably to vent water vapor. I plan to use a minimum of small 1/4" holes (maybe 5-8 of them) for this purpose. Is there a discussion on this anywhere? What do most FB builders do?

gjbingham 04-15-2008 08:04 AM

Re: Moldit-D and Transpiration
There has been discussions regarding the venting of enclosures. Try the search function at the top of the page. If that is fruitless, read through the entire forum on finishing/enlcosures. You can pretty quickly rule out the threads that don't apply to your situation. Sounds like what you have planned should be pretty functional though.

dmun 04-15-2008 12:03 PM

Re: Moldit-D and Transpiration
If you are building your enclosure out of brick they make a nice aluminum brick vent, that just takes the place of one brick, and it's not bad looking either.

Sorry I don't have better pictures. If you are using wonderboard over metal framing, you can use an ordinary soffit vent, although cutting a round hole will be somewhat harder than in wood.

Venting the enclosure is not standard procedure. It seems to me that it's unlikely to cause a problem, as it would in a wooden attic.

CanuckJim 04-16-2008 05:52 AM

Re: Moldit-D and Transpiration

I used brick vents as well on my oven. I think the major reason is to make sure the insulation remains dry and air humidity does not have a chance to get at it. I really don't think just drilling holes, especially that small, will be adequate. The actual oven enclosure on my oven has the brick vents, while the gable roof area uses standard soffit vents.


gjbingham 04-16-2008 10:52 PM

Re: Moldit-D and Transpiration
What if you live in Florida and the humidity is 95 percent all summer long. Certainly, the humidiy gets in/out depending on the weather conditions. This whole idea stumps me a bit. It seems like any moderate amount of venting will allow the internal and external humidity levels to equalize.

I assume ( I know, ass of you and me) the venting is primarily to allow moisture to escape as the oven cures. After that, the oven is subject to whatever weather conditions exists around the oven. If the enclosure is watertight, it seems like just a few and smallish vent holes would be adequate. I'm not second guessing you and David, just curious.

buckeye 04-21-2008 12:50 PM

Re: Moldit-D and Transpiration
Thanks for the would seem, after putting everything together, that a minimal number of holes will suffice. I may also consider the small round slotted aluminum disks that are sometimes used to vent construction. It seems that few vent their structures (especially dome builders) and I haven't heard any disaster reports from failure to vent, so I'm not going to agonize over it.

As for the Moldit-D, it looks like no one has had experience with it so I'll let you know how it goes...

Johnny the oven man 07-02-2008 06:14 PM

Re: Moldit-D and Transpiration
Moldit d is a 1300c refractory castable, so yes, can cover your dome with it.

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