Rich Covert wrote:
I am in the process of of building a clay oven and would like some input.... I have a large piece of white marble I have scavenged and would like to use for the floor in the oven. Seemd like it would be a great surface to cook on but I am unsure about the thermal characteristics of marble for this use. I am aware of the potential of certain rocks to explode when heated but I have seen stone used in ovens to cook pizza on. Anyone have any thoughts?
Besides the exploding aspect... The thing to watch for is conductivity of heat. If the stone is too conductive the bread will burn because the stone gives up it's heat too fast. The stone that is most often used is soapstone. I get the idea it is ok for pizza (with a live fire while cooking) but bread still tends to burn (probably it would be fine if the baking was started at a lower temp to begin with or a more porous support to slow the heat supplied to the soapstone).
Now I am no geologist, but it would seem to me that the harder the stone, the higher the conductivity. That is the first thing to look up. Soapstone is one of the softest stones around. The more weight per volume does mean it would store more heat (a good thing).
The cracking/exploding can be tested by putting it over a fire.... once the inside temp makes it past boiling.... I would try taking it as high as I could.... any water pockets will be steam. stand well back. Maybe someone else knows if marble is likely to have water pockets at all.
If you do use it. You are dealing with a different animal than anyone elses oven. Its characteristics and heating/cooling profile will be different than anyone elses oven, so you will have to learn by trial and error. How long to burn, what temp to bake what at, how long it takes to soak after firing and before baking.... All those things. You may find just a layer of splits on top is all you need.... make them removable for pizza. I think I would try it.... if I didn't decide I would like a marble work surface more.