iandol on sun 27 apr 03
<<boron to affect the color? Hence you are willing to eliminate it?>>>
Dear Lily Krakowski,
I deleted Gerstley Borate for several reasons, the least of which is its =
obsolescence. Unless it has been included to eliminate Crazing it is =
generally unnecessary for a Cone 10 glaze which contains an adequate =
supply of melting agents. In this case, it is probably the agent which =
was causing problems because of its low melting point. It may also =
contribute to increasing fluidity as temperature rises. Soda Ash was =
eliminated because it has such a low melting point and it may also =
induce crazing problems.
Colour, if you mean the blue in a boron rich glaze due to phase =
separation, may be immaterial since the person was using strong =
colorants. My experience with Borax bead tests leads me to believe that =
colours in a borax glass are usually true. The inclusion of Barium =
Carbonate might have a greater influence on the copper colouration.
Best regards,
Ivor Lewis
Craig Martell on mon 28 apr 03
Ivor commented:
>I deleted Gerstley Borate for several reasons,
>It may also contribute to increasing fluidity as temperature rises.
Hello Ivor and other glaze enthusiasts.
As I recall, this glaze also contains some barium and there can be a
reaction with barium and boron that produces very fluid melts. This may
not be the case with this particular glaze, but it's a possibility. I
think the boron is expendable here but the barium probably contributes to
the formation of copper blue because of it's alkalinity.
regards, Craig Martell Hopewell, Oregon
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