Ivor and Olive Lewis on tue 7 sep 04
Dear Steve Slatin,
You give us an interesting argument.
<< It's tempting to presume that there will be no difference, as by
final melt temperature the silica "should" be completely integrated
into the final glaze, >> This seems to be a truism for all glazes.
Surely it is our hope that all free silica, regardless of its origins,
should dissolve in a maturing glaze. None will melt until the
temperature rises beyond ~1710=BA C without the help of some sort of
solvent, be it Boric oxide, one of the low melting point Alkali
silicates or a Frit.
Another point is that if the Silicon Dioxide present in quartz is
"Silica" and the Silicon Dioxide in "Flint" is also Silica as Hamer
says, then they both have the same lattice structure and this will
only change when rising temperature causes a phase change.
Is the Silica in Flint "Amorphous"?. Hamer tells us it is
"Cryptocrystalline".
To be amorphous we must change Silicon Dioxide into a "Glass". This
might be expected to melt at a temperature somewhat lower than
crystalline forms. But at what temperature I would not know. Nor have
I seen it put up for sale by suppliers.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
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