Richard Mahaffey on sat 5 jun 04
Hello,
I have a Korean Yi dynasty bowl with a similar grey glaze. I would
not characterize it as a gray shino. Real (Japanese) shino glazes are
thicker.
A feldspathic clear glaze, when properly reduced below cone 4 produces
a grey color under the glaze. This body reduction changes the iron to
a gray color and the glaze seals the underlying clay from re-oxidizing
to a brown color. We use a variation of the Leach's Limestone clear
from a potters book. It is a glaze with a fair amount of calcium in
it. We reduce from come 08 or lower until at least cone 5, but
usually reduce the whole way to cone 10. There is one difference
between the glaze I mention (formula is at school, I can post it
tomorrow) and the Korean Yi dynasty glaze. The Korean glaze is thinner
and softer almost like a Raku clear, where the Leach limestone clear is
thicker and looks to be harder.
Rick
Tacoma Community College - one more week to go. Firing like mad!
Tacoma, Washington, USA
Carissa Doying Salazar on sat 5 jun 04
Hi Rick,
I know it is difficult without a visual or tactile sense of this bowl
to understand my words. I am sure your bowl is very beautiful.
However, the glaze I am looking at is opaque, thick and hard. The gray
color is in the glaze not underneath it but thank you for trying to
help.
Carissa
>I have a Korean Yi dynasty bowl with a similar grey glaze. I would
>not characterize it as a gray shino. Real (Japanese) shino glazes are
>thicker.
>
>A feldspathic clear glaze, when properly reduced below cone 4 produces
>a grey color under the glaze. This body reduction changes the iron to
>a gray color and the glaze seals the underlying clay from re-oxidizing
>to a brown color. We use a variation of the Leach's Limestone clear
>from a potters book. It is a glaze with a fair amount of calcium in
>it. We reduce from come 08 or lower until at least cone 5, but
>usually reduce the whole way to cone 10. There is one difference
>between the glaze I mention (formula is at school, I can post it
>tomorrow) and the Korean Yi dynasty glaze. The Korean glaze is thinner
>and softer almost like a Raku clear, where the Leach limestone clear is
>thicker and looks to be harder.
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