[Stoves] Glass Stoves

[Crispin Pemberton-Pigott]

Dear Friends

I was speaking to a glass technician about the possibility of making stove components out of low expansion glass.  He thinks that the expansion is too high but offered the following benchmarks:

Ordinary glass can take a temperature difference of about 100 degrees C from one side to the other.  If you heat a piece of such glass to 100 and pour cold water on it, it will probably not break.

Pyrex (boron silicate) glass can take about 300 degrees of thermal shock.  The top of some stoves is a flat sheet of glass and the electric elements underneath get red hot. The temperature difference between the two sides must surely be greater than 300 degrees, yes?  They do not break if you drop water onto the hot area.  So I am wondering if there is another type of glass that is 'beyond Pyrex' and which can take high enough shocks to be used as a wood stove component, for example the grate.

Something that would be useful is if any of you can corroborate the thermal expansion figures this guy mentioned:  90 x 10^-6 for regular glass and 30 x 10^-6 for pyrex-type glass without soda-ash in it.  My gut feeling is that these numbers are impossibly high given that clay is typically 7.  Perhaps they are 9.0 and 3.0.

Anyone have comments on this?

Thanks
Crispin