Karen Sullivan on wed 29 nov 00
My humble opinion, and perhaps not as technically described but
the firing of green clay is done slowly up to color/around 1000 degrees.
The stages are, candle at 212 degrees, to drive off the physically
combined water that the clay has. Past 212 degrees water boils and
like water boiling in a pan, the eruptions break the surface with a
lot of energy...You don't want to trap water in the clay that erupts out of
the body and causes explosions by carrying some clay with it...
So a duration of time to candle.(I would be curious of descriptions
for those who live above sea level)
Then slowly climb in temp. until color/1000 and you have gone
through quartz inversion.
Chemically combined water is driven off around 1100 degrees....
1400 degrees/some time in that range you have burned out the organic
material in the clay.
Once you go through those processes, you can take the clay to any
temp.
So once fire, you fire the beginning stages as tho. a bisque
and finish at the temp. the glazes mature.
hope that helps...
You need to know that I am humbled with your glaze efforts, and
appreciate your efforts and generosity.
bamboo karen
on 11/29/00 12:53 PM, Alisa and Claus Clausen at aliskin@MAIL.DK wrote:
> Hi Steve,
> Now my interest is perked again.
> I have tried a few single firings and no such good results.
> First all the greenware cracked up, then the pieces that
> survived the glazing, either went slumpy or bust under
> the firing. Admitedly, I had not done too much homework
> on the process.
>
>> From your vast experience with single firing, do you think
> that I could example omit my bisque by painting on the same
> glazes I normally use with the addition of CMC instead of
> reformulating glazes with more clay?
>
> What about firing ramps? Do they not need to be much slower
> than normally up to around 500c?
>
> I asked about some of this about a year ago when I first signed on
> the list. I never got to far with it. But, for some of my work, I could
> certainly use single firing, especially the bigger pots.
> I would at all cutting back on my enormous electrical bill every quarter.
>
> What range do you fire in? If it is 6, do you have any basic glaze
> receipes I could use for a base? This would be very exciting test
> trials for me, to do on green tiles!
>
> Thanks in advance,
> Best regards,
> Alisa in Denmark
>
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