iandol on sat 16 feb 02
Dear Marjorie,
There are several functions or processes which happen when this is done. =
The first, not generally recognised, is that it allows what glass makers =
call "fining time". That is, time for all of the materials to melt and =
meld or diffuse among each other to give an homogenous material. This =
includes time for "seeds", that is fine bubbles, to surface and break =
and the scars they leave in the surface to heal giving a pinhole free =
surface. The second is that it allows the glaze to fully bond to the =
clay beneath it. Thirdly, as cooling happens crystals start to grow in =
the molten viscous silicate glass. Fast cooling suppresses this phase.
These are physical and chemical reactions. They are influenced by the =
materials we use, by the degree of grinding our materials have received, =
by the intimacy achieved in mixing and by the cone value to which we =
fire.
I am sure there are other things which will emerge as people think about =
it.
Regards,
Ivor Lewis.=20
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