Thinking of Casting

[aferaci]

I'm thinking about casting my oven with a product called Kaocrete. The manufacturer is only 45 mins from me so I wouldn't have to pay shipping. It's only about $25 a bag. My only question is whether or not it would be a good product to use based on it's content. The alumina is 47% and the silica is about 40%. The technical sheet can be found here for all of the kaocrete products. http://www.thermalceramics.com/upload/pdf/314-105.pdf

Thanks,


Tony

[Wiley]

Re: Thinking of Casting

As long as you have access to a kiln large enough to properly fire the cast WFO or a plan for doing it (ie: home made brick kiln, wood fired or whatever) I'd give it a try. I've built small furnace's using similar materials but upon recommendation of AP Green I designed my furnaces such that each piece could fit into a pottery kiln that was available to me and be fired at proper temperatures under controlled conditions. Not saying you couldn't cast one, cure it and burn it in the middle of a bonfire and not have it come out OK. If you have a couple of hundred bucks to venture and the time... I'd go for it.

But then consider the source... I'm the guy building a WFO around a steel dome :-)

Wiley

[enz]

Re: Thinking of Casting

aferaci,
I cast a 42" Low Dome about a year ago from Mizzou Castable from Harbison Walker. I chose this material since it matched both the thermal mass and conductivity of fire brick. I posted a series showing the male molds I used right after I finished it, in Tools, Tips and Techniques, I assume it's still back there.

After something like 25 firings, what did I learn?:

The dome needs to be cast in ONE pour. You will get fine cracks where the pours meet. You will need an external mold as well. We tried to work our way up the molds without one and failed miserably. You only need a mold about 2/3's of the way up, after that you can just mound it. These cracks don't seem to affect performance or strength (I've jumped on the dome).

Cure slowly and steadily just like everyone else. You need to hit a certain temperature to achieve maximum strength. For the mizzou it was 1250 F. Once you do your perlcrete or other insulation you should have no problem hitting that with hardwood. I hit 1600 interior temp, so the outside probably hit 1250.

Most of all go for it. It is far better to have a pizza oven than to go without!

Enz