Pompeii oven as a kiln?

[Frances]

mmmhumous asked this on my thread and I think its a really interesting question...

So what do you all think, would it be possible to use a pompeii oven as a kiln? Say to glaze tiles or fire pottery?

[DrakeRemoray]

At a minimum I would be worried about eating pottery glaze on my pizza...

Drake

[dmun]

We use the same refractory materials that kiln builders do. I don't think it's a good idea, though. Heavy metals and all that.

[Wiley]

FWO are not designed or built for firing ceramics but that's not to say it couldn't be done.

I think you would have to define exactly what you mean by ceramics. Certainly if one wished to fire long and hard one could create some level of fusion of either a porcelain or teracotta. Perhaps a teracotta as in cheap inexpensive Mexican (or other third world) type pottery. Procelain would be more limited but I suspect under something like a small overturned flower pot over a unglazed plate could create a suitable environment for fusion. And certainly the low lead based glazes would also work although there is the mentioned problem of heavy metals. Perhaps one could create some interesting small pieces. But control of temp and time would be problematic and the wear and tear on the oven would be, I suspect, considerable.

I also used to do enameling, a small home business, and it has been a couple of years since I did any firing. Enameling is sort of between ceramics and glass work. Temps are comparably low running from just around 800 F to 1300 F or so. I built my own computer controlled muffled kiln or furnace and so I have a little experience with such things. I have toyed with the idea of "ground coat" enameling the inside of the steel dome which I am building my WFO. The ground coat is the first layer used on enameled steel, it's the coating on the inside of your conventional kitchen stove. I expect it would burn off directly above the fire but the rest of the interior should be fine. When the weather becomes more tolerable I will be doing some test pieces.

Here's a photo of some of the sort of stuff I used to do. The two on the left are on steel and the three on the right are on ceramic tiles.

Wiley

[james]

Originally Posted by dmun

We use the same refractory materials that kiln builders do. I don't think it's a good idea, though. Heavy metals and all that.

I'll second that. I don't think food and glazes should mix. :-)

James

[asudavew]

I used to be a decent potter.
Most glazes fire at around 2300f.

I don't think you could ever get the oven that hot.

Kilns are made with insulating bricks that are fine up to 2300-2700.

But you sure could build a small kiln out of expanded metal and a ceramic insulating blanket.

[brokencookie]

the only glaze that goes near my food is Rosemary Rhubarb Glaze

Bruce

[Frances]

Thank you for discussing the idea...

My main thought was to glaze some shards of pottery for the mosaic on the outside of the oven... but if that means I risk ruining the inside of the oven - I think I'll give it a miss.

Hey, I could always build a kiln beside the pizza oven!

[david s]

For a pottery kiln you need insulating refractory rather than dense refractory and to achieve the higher temps required you really need a downdraft system ie the flue enty at floor level so the flames rise and then are pulled down and out. Wood fired kilns typically take days to reach stoneware temps (1200+ C)
Earthenware temp a little easier at 1150 + C and porcelain 1300 C Fuel required to go from 1000 to 1200 would be more than that required to get to 1000 because of expotential heat loss the higher you go. Forget trying to fire pottery in an oven designed to cook food that only goes to a piddlng 400 C

Sorry about the temps in centigrade for you lot back in the dark ages, I'm sure you can convert the numbers. Not so sure about yor systems. Joking
Dave