Louis Katz on thu 29 may 03
I have used a glaze like this in the past, and I continue to use it to
illustrate the process of glaze calculation. Using theoretical
compositon for the ingredients it comes out very close to
1 part whiting
1 part kaolin
1 part silica
I call this glaze Katz 111 Celadon. A play on Leach 1234. I am told not
to expect it to be very resistant to mild acids, but I should have it
tested. It has an odd old linoleum dull green color to it when some
iron is added. I fire cone 9-10. It shows not much fluidity, is a
gloss, and my memory says it fit my clay body reasonably well.
I have proposed doing a quick lecture on learning glaze calculation in
at NCECA next year. If I do it I will sue this as an example.
Louis
>
> This can be shown as untrue by making a glaze to match the formulation
> of the 1170 deg C Eutectic (CaO~23%-Al2O3~14%-SiO2~63%) from Alumina,
> Silica and Whiting, quite easy for someone with a glaze calc program.
> Common sense tells us that it will be well fused at Cone 6.
> Observation may show this is not the case. Do the test and tell us of
> your result.
>
Ron Roy on fri 30 may 03
Hi Louis,
Good to hear you on ClayArt - missed you!
Pretty close - little high on the Al2O3 and a little low on the SiO2 -
interesting it would melt at 9-10 - expansion is right in the ball park.
It is kinda short of silica for a durable glaze but it is way up there in
CaO. One of the interesting part of Johns experiments was the good effect
CaO had on stability - some of the glazes in our book are way over the
limits for CaO and yet are still stable. I note in the Taylor and Bull book
that high CaO in a glaze can cause divitrification (recrystallization) so
keep fast cooling if you want the gloss.
Let us know if you do have it tested - just dump in 5% copper Carb. and 5 %
rutile and count the copper that comes out.
RR
>I have used a glaze like this in the past, and I continue to use it to
>illustrate the process of glaze calculation. Using theoretical
>compositon for the ingredients it comes out very close to
>1 part whiting
>1 part kaolin
>1 part silica
>
>I call this glaze Katz 111 Celadon. A play on Leach 1234. I am told not
>to expect it to be very resistant to mild acids, but I should have it
>tested. It has an odd old linoleum dull green color to it when some
>iron is added. I fire cone 9-10. It shows not much fluidity, is a
>gloss, and my memory says it fit my clay body reasonably well.
>I have proposed doing a quick lecture on learning glaze calculation in
>at NCECA next year. If I do it I will sue this as an example.
>Louis
>
>>
>> This can be shown as untrue by making a glaze to match the formulation
>> of the 1170 deg C Eutectic (CaO~23%-Al2O3~14%-SiO2~63%) from Alumina,
>> Silica and Whiting, quite easy for someone with a glaze calc program.
>> Common sense tells us that it will be well fused at Cone 6.
>> Observation may show this is not the case. Do the test and tell us of
>> your result.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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