Arnolds Home Improvements on thu 30 jan 03
Does anyone have a high alkaline transparent base glaze recipe for cone 6 ox
they would be willing to share.
I say a beautiful dark green at a recent show and the young lady working the
booth said it was a high alkaline.
So I thought if I had a high alkaline clear base I would do some
experimenting and see what kind of greens that it would yield.
Thanks for any help!!!
Gene Arnold
mudduck@advi.net
Wanda Holmes on fri 31 jan 03
Gene,
I have been experimenting with high alkaline glazes for the past several
months. If crazing is not an issue for you in your work, you're home
free. You can begin with 80% alkaline frit to 10% epk and adjust from
there.
However, if you want a durable high alkaline glaze with a characteristic
alkaline color response, you are tackling a very difficult problem. The
alkaline oxides sodium and potassium have very high
expansion/contraction rates, AND the color response requires low levels
of alumina - a double whammy in trying to correct crazing.
I have substituted lithium for KNa to lower the COE (coefficient of
expansion) to very low values, but these glazes sill craze. I can't yet
explain this scientifically (glaze gurus jump in here), but I believe it
must have to do with viscosity, surface tension, or 'weakness' in the
resulting glass. (Incidentally, I can also produce crazing in a low COE
glaze by adding high levels of silica.)
Another problem I've had is that many of my low alumina tests have
devitrified - sometimes to interesting effect and other times to
something really ugly.
I am in the process of rethinking my testing strategy for one more go at
this before deciding that it is a hopeless quest. I'd be very
interested in your findings.
Wanda
Austin, TX
Praying that we get some sun soon - before I run screaming into the
gloom
Ababi on fri 31 jan 03
The recipe I have tried is impossible over-your side.
I can suggest to try using 20-30 kaolin 65-78 frit 3110 and 2-5 lithium carbonate.
When the too expensive frit I have will be gone, I will do it too.
Ababi
---------- Original Message ----------
>Does anyone have a high alkaline transparent base glaze recipe for cone 6 ox
>they would be willing to share.
>I say a beautiful dark green at a recent show and the young lady working the
>booth said it was a high alkaline.
>So I thought if I had a high alkaline clear base I would do some
>experimenting and see what kind of greens that it would yield.
>Thanks for any help!!!
>Gene Arnold
>mudduck@advi.net
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