Layer of vermiculite and super isol, Good or Bad?

[camarina73]

wanted to put 4" of concrete super isol and 2" of vermiculite in that order. That will put my top of landing at 42.5". Two questions. 1. Is that to high? and 2. Can I pour the concrete slab, Put super isol on top with no adhesive and then pour the vermiculite over? I wanted to do this so I would not have to adhere super isol to vermiculite layer. Please let me know your thoughts thank you.
Carlo

[dmun]

Generally speaking, you can't have too much insulation, but this may be pushing it. 4 inches of vermiculite concrete, or the equivilant 2" of super-isol is what is recommended. There is no harm in using too much, but if you are going to go wild on insulation, do it on top of the oven: Heat rises, after all.

I don't think you need both the super-isol and vermiculite concrete. Just build your support slab, and put one or the other on top.

[james]

I would agree. Using both insulators under the oven would require too much work. If you really want to do a great job of under oven insulation -- which is a very reasonable thing to do, you could either build up to 6"-8" vermiculite, or use two layers of Super Isol to 4".

That way you get great insulating values -- which I want to emphasize is perfectly reasonable, but you don't have to work with both products -- mixing vermiculite concrete and cutting and glueing Super Islo. Pick your poison, and stick with it. And build the insulating thickness you feel good about.

James

[camarina73]

but if i set the super isol on top of the concrete without gluing it and pour the vermiculite over wouldn't this hold it and not need glueing.
carlo

[james]

Hey Carlo,

Vermicutite concrete feels like Oatmeal when it's wet, and is kind of crumbly and porous when it sets. It has good compression strength to hold up your ovne, but it isn't good at holding anything together. I can't see any advantage to using both vermiculite and Super Isol together.

It's easy to hold the Super Isol board in place with either refractory mortar or the glue that is recommended for it. Or you can mix and pour the vermiculite concrete -- but you don't have to both. Save your evergy for building the oven chamber itself.

James

[ljanmi2]

Refractory glue for Super Isol

Is this glue supposed to be used underneath SuperIsol boards to fix them to the layer below, or on boad edges to join them together and make one big SuperIsol board that is large enogh for the oven that sits on top of it?

Mike

[james]

If you use the glue, it would be easy to put a little glue between the boards to hold them together a little bit, but the main idea is to hold them down and in place on the concrete slab using the glue, or mortar. The board has a nice straight edge, so it's easy to set the different pieces perfectly tight against each other.
James

[redbricknick]

isol geodesic dome.

I want to make a geodesic dome out of super isol board and put it over my firebrick dome. I figure I can pre build the geodesic dome to size, and install it gradually, filling whatever cavity I have with perlite. Will this be enough insulation?

[dmun]

insulation

I want to make a geodesic dome out of super isol board and put it over my firebrick dome. I figure I can pre build the geodesic dome to size, and install it gradually, filling whatever cavity I have with perlite. Will this be enough insulation?

Since two inches of super-isol equals 4 inches of vermiculite, which is the recomendation for igloo instalations, that should be plenty.

Remember: Super-isol is porous, and you need to put something waterproof over it to keep it dry. At one point I thought about putting a hard shell geodesic made of terra cotta floor tiles (it should be self supporting) and filling the cavity with vermiculite before putting the cap on.

[wlively]

Blanket?

I want to make a geodesic dome out of super isol board and put it over my firebrick dome. I figure I can pre build the geodesic dome to size, and install it gradually, filling whatever cavity I have with perlite. Will this be enough insulation?

Since isol board and insulfrax serve the same function, why would you want to cut/piece/glue the board together when you can just lay down the blanket? If you want to make the blanket hard, they sell rigidizer liquid which turns the blanket hard.
http://cgi.ebay.com/Refractory-coati...QQcmdZViewItem

Wade

[redbricknick]

geodesic igloo

Esthetics. We want our oven to have a shiny black mosaic tile look, and mosaicing flat tile on top of a rounded surface is very difficult. Achieving a true round igloo is a near impossibility. A geodesic dome however, is made up of flat surfaces, making tiling easy.

[CAM]

rigidizer

Would the rigidizer be recomended if one went straight from 3 layers of insulfrax to the stucco layer. Does it degrade the insulating properties?
Would you use it on just the outer layer or all 3?

Thanks, Chris

[wlively]

Redbrick

Gotcha. Good Luck.

Cam

From what I understand the rigidizer degrades the performance when the temps exceed 2000 deg, so you would probably want to put it on the outside layer, if you were going to use it. There is also another coating called ITC-100HT. It actually increases the performance of the blanket and reflects heat. You can find info here; http://www.budgetcastingsupply.com/ITC.html

[CAM]

Coatings

Thanks for both sites and the info. Sounds like the rigidizer would do well. 2000f shouldn't be a problem, especially if you put it on the outer layer. Thanks again.

[janprimus]

sorta rigidizer

I used the rigidiser on my Kaowool and it is not really that stiff. It is stiffer, but it is certainly not a shell like I was hoping for. That being said, it will work fine for what I am doing, so I am not unhappy. As for the 2000? , most pizza will burn pretty fast at those temps. ;-)
Chad