[Cob] fire brick?

[Amanda Peck]

My mother had done a fair amount of pottery in art classes, and all she ever 
told me was that fire brick stayed intact longer than regular brick in high 
heat situations.

I can see where both arguments could be made of the same brick--blowing hot 
and cold with the same breath.

A layer of fire brick is a lot thinner than a layer of standard brick, so 
heat would pass through it to the underlying layers faster.  On the other 
hand there ain't no holes in it, so given the same thickness, it might 
retain heat longer.  Given that we have (at least) three hands here, on the 
third hand, might it be less dense than regular brick?

Doesn't help much to know what to do with your curved fire brick.  I wonder 
what that was originally intended for?  Is it curved in one plane as in a 
vault or a circle, or in two, as in a dome?

(my all-time favorite Charles Addams cartoon involves a harrassed wife 
juggling the baby and trying to fix dinner for her tattooed husband in the 
carney caravan, crying "I've only got three hands!")

Here's a link talking about using firebrick in ovens (cob would work instead 
of concrete, but....:

http://www.traditionaloven.com/

"Wood ovens, particularly ovens made using firebricks, have domes that are 
only about 4 inches thick (10 cm). If well insulated on outside, then this 
is perfectly satisfactory for pizza and then short time baking. But once you 
decide to build your own wood burning oven and after pizza do long time 
baking or large meats slow roasting, consider making the walls up to 6 
inches (15 cm) thick by adding on 2 inches concrete cladding layer, such 
brick ovens will stay hot enough to cook for at least 6 hours using the heat 
energy generated at pizza making time (it's a worthy project and heaps of 
fun). Your oven will be a lot more efficient and stronger. You may need to 
heat it up a little longer, but those 20 minutes and a few bucks extra for 
concrete gravel etc. will pay you well off and you will be more happy in the 
end."

Not what I was looking for, what I had been looking for was a firebrick oven 
kit, made with curved bricks.  But the site might be remarkably useful.

..................
   Cat here

   I have been given conflicting responses to the use of fire brick in
   bread ovens?  A potter tells me that they will keep the oven hotter
   longer giving a longer baking time, and a slower cooling surface.  She
   told me that the oven will be relesing heat into the room two days
   after fire.  Much like a masonary or Russian stove.   A brick mason
   told me that fire brick is made to pass heat quickly to the surface
   and protect the interior of the stove from damage??? This is to get
   heat into the room faster and less heat in the fire box.  I just got a
   few boxes of curved fire brick at a scavanger sale.  I must
   decide where to use them.  The bread oven or the heating stove.  Ok so
   I got to figure that their are two kinds of fire brick? Or their is
   something that I'm not understanding about fire brick.  Most use I
   have seen it is layed loose into the stove and can be repalced. Anyone
   been up this ally got any suggestions?
   for the good of all C.
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