Ivor and Olive Lewis on sat 13 jan 07
Dear Ron,
You tell us "Boron is not necessary for a stable glaze - at least not =
between cone 6 and
up. The 4 criteria are well documented in our book by the way - enough =
alumina, enough silica, a good melt and not oversupplied with colouring =
additions."
I agree with your summary of the necessities that will better ensure the =
indestructibility of a glaze. With John you put forward a well argued =
case, fully supported by experimental evidence. This makes your book one =
of the most valuable resources in the field of pottery today
But are the terms "Stable" and "Indestructible" synonymous, when used in =
reference to glazes ?.
Singer and Singer, in their introduction to Ch 6 "Glazes" say " Glazes =
are thin layers of glass fused to the surface of the body. They are =
applied to bodies to make them impervious, mechanically stronger and =
resistant to scratching, chemically more inert and more pleasing to the =
touch and eye" Nowhere can I find they say glazes are Stable or how they =
achieve that state. They do speak of "Devitrification". That is a phase =
change governed by Composition, Time and Temperature. They do speak of =
Corrosion and that is due to interaction with other chemicals. But do =
they discuss "Stability" ?
Thanks for allowing me to be idiosyncratic.
Best regards,
Ivor
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