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Re: bread stones and wood-fired ovens

yguaba@yahoo.com.br
Mon, 16 Aug 2004 10:38:20 -0300
v104.n037.2
Hello Forrest,

On 5 Aug 2004 at  06:14, nonbearded.2590910@bloglines.com wrote:

>So the question is, can granite stand the 700 degree temps that these 
>ovens reach?

Granite is one of the hardest rocks there is, so it is extremely resistant. 
But to be absolutely safe, look for the granite with the finest grain you 
can find. I don't know about Japan, but the granite most commonly used for 
gravestones is black, which has extremely fine grain (and additionally, 
because of the colour, retains rather than reflects most of the heat), so 
it should be perfect.

A little science: it is the difference between the thermal expansion 
coefficients of the various different crystals that make up a rock that 
cause it to crack, since some crystals expand more rapidly than others. A 
finer grain indicates smaller crystals, which result in a more homogeneous 
rock with minimal internal differences in thermal expansion coefficients.

Hope this helps,

Erik