Kaowool Refractory Ceramic Fiber Insulating Board

[Ken524]

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UPDATE - 12/20/2007:

After completing my oven, I can NOT recommend using Kaowool board under the oven. Due to moisture in the board, parts of my oven are settling (sinking) into the moist, mushy board and causing cracks and joint failures. Please: Don't use this stuff!!. Stick with vermiculite concrete or the SuperIsol sold by Forno Bravo.

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I think I may be the one of the first to use Kaowool rigid insulation board under my oven so I thought I would do a review of the product.

When shopping for the board, I had a choice between 1" CalSil board (stacked to get 2") or 2" thick Kaowool. I went with the Kaowool so I wouldn't have to monkey with stacking CalSil sheets.

Manufactured by Thermal Ceramics, the product is shipped 3 sheets to a box. Dimensions are 2' x 4' x 2". Several grades of board are available. The stuff that was available to me was Kaowool M - Low Temperature Board (2300 degrees F). Spec Sheet
Price was $10USD/SqFt (very high).



Comparing the spec sheets of SuperIsol and Kaowool, it looks like the SuperIsol is the stronger, sturdier of the two products (I'm not much of an engineer... if anyone can do a real comparasin of the two sets of Spec numbers, I would appreciate it!) I can push my thumb into the Kaowool and feel it "give" with a few pounds of pressure. I don't think there will be a problem with supporting the oven. When dry it's pretty dense. If the dome sinks at all, it won't be more than a few millimeters. I really doubt it will. Too much surface area.

The board was easy to cut with a jigsaw and light enough for one person to comfortably handle.

Positioning the floor bricks on it was easy. There is a level, smooth, dark side and a slightly textured, lighter colored side. A friendly engineer at Thermal Ceramics told me either side can face the heat. I also told him what I was doing with the board and he said it should work just fine.





I have not used SuperIsol/CalSil board. But from reading about others experience, it appears that the Kaowool is more susceptible to moisture damage.

This picture was taken after I finished gently sponging the excess mortar from my brick.



Once wet, the ceramic wool really gets soggy and easily comes apart. Each time I got near it with the sponge, some of the dark, smooth surface flaked away. After an hour or so in the sun, it returned to it's original firm state.

My analysis: I think this stuff will work fine. After everything is sealed up, I don't anticipate moisture will be an issue. The Kaowool is more expensive than other competing products (WAY more expensive than vermic-concrete). If I did it over again, I would go with the double set of 1" CalSil sheets or even the vermiculite.

[Archena]

Probably would work great for an indoor oven...


~runs off to bookmark page~

[rlf5]

Your boards seem to perform about the same as mine. I was able to get a box, more than enough material, of 6 or 8 sheets for $96. They were 12"x36"x2" boards. I started mortaring today, but I didn't put any mortar on the bottom side of my floor bricks. Should I be doing that?

[Les]

RL,

I just used the clay sand mix to level out the seams on my boards. If you are level, I don't think you will have any issues. Ken brings up a point of concern though about it getting wet. What's going to happen to us when rain / snow flies into the entry way. I think we are going to need a cover to protect that part of the oven. Just another project for the project

Les...

[Ken524]

Originally Posted by rlf5

I started mortaring today, but I didn't put any mortar on the bottom side of my floor bricks. Should I be doing that?

I don't have any mortar between any bricks and the insulation boards. I leveled the floor bricks where necessary with fire clay (reclaimed from my HF saw).

My soldier course is sitting directly on the board. It's firm and level. As it's been said before, gravity will assure the dome won't be going anywhere!

[Ken524]

Originally Posted by Les

RL,
Ken brings up a point of concern though about it getting wet. What's going to happen to us when rain / snow flies into the entry way.

I'm not too worried about moisture entering the dome and getting below the floor. I'm definitely building a door for the oven that will stay in place when not in use. The floor bricks under my vent and landing will be mortared for weather resistance.

[rlf5]

Originally Posted by Ken524

I'm not too worried about moisture entering the dome and getting below the floor. I'm definitely building a door for the oven that will stay in place when not in use. The floor bricks under my vent and landing will be mortared for weather resistance.

Oh then that must be your sand/clay mixture. My mistake!

[Ken524]

Originally Posted by rlf5

Oh then that must be your sand/clay mixture. My mistake!

I'm not sure what you mean... I'll clarify just to make sure: The floor bricks that are under my vent and landing will be sitting directly on the insulation board like the others. I will use HeatStop to mortar these bricks together to inhibit moisture intrusion through the cracks.

[rlf5]

Originally Posted by Ken524

I'm not sure what you mean... I'll clarify just to make sure: The floor bricks that are under my vent and landing will be sitting directly on the insulation board like the others. I will use HeatStop to mortar these bricks together to inhibit moisture intrusion through the cracks.

Oh i see where the confusion is coming from. The top of your boards are a totally different color than the middle of the board. That dark top part of the board made it look like a layer of mortar under the bricks. Again, my mistake.

[Ken524]

Originally Posted by rlf5

The top of your boards are a totally different color than the middle of the board. That dark top part of the board made it look like a layer of mortar under the bricks.

Ahhh... Got it. Yeah, the boards have a dark, flat side to them. Looks like dark 60 grit sandpaper. The other side of the boards are cream colored and textured.

No problem! Happy to clarify.