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How Much Underfired?


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#1 nairda

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Posted 22 May 2012 - 01:54 PM

Our community kiln showed a firing error on the digital controller indicating the kiln was shut down due to the temp rising too slowly in a bisque. The pieces look 'bisqued' but don't feel the same as usual. The digital info indicates it only reached about Cone 016, not Cone 06. No pyrometric cones were used in the firing, but if it's as underfired as the digital readout indicates, they wouldn't have provided much info. Should we be reluctant to glaze fire these pieces until they have been re-bisqued?

#2 Pres

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Posted 22 May 2012 - 02:44 PM

Our community kiln showed a firing error on the digital controller indicating the kiln was shut down due to the temp rising too slowly in a bisque. The pieces look 'bisqued' but don't feel the same as usual. The digital info indicates it only reached about Cone 016, not Cone 06. No pyrometric cones were used in the firing, but if it's as underfired as the digital readout indicates, they wouldn't have provided much info. Should we be reluctant to glaze fire these pieces until they have been re-bisqued?


You may still glaze these pieces-I have done so myself when under fired bisque. However, when I do a firing of under-fired bisqueware I usually slow my glaze firing at least to around 1100F. At the same time I try to slow down the last part of the firing to allow pinholes from gasses to smooth over. I would be concerned about the problem with the kiln firing to slowly to cause it to shut down. Have you used this program before, are there any elements that looked damaged? Is anything else about the kiln different.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#3 TJR

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Posted 22 May 2012 - 03:30 PM

Nairda;
You should be O.K. to glaze your pieces. Be aware that they may be more porous than usual and will soak up more glaze.Try to avoid getting your glaze on too thick.I would look at your firing bisque cycle and readjust it to fire more quickly.
TJR.

#4 neilestrick

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Posted 22 May 2012 - 04:06 PM

Go ahead and glaze the, but fire on a slower setting. Fix the kiln first.....
Neil Estrick
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neil@neilestrickgallery.com

#5 nairda

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Posted 22 May 2012 - 10:21 PM

Thanks for the input! I think aging elements are to blame. Will test them tomorrow. Don't think it's worth firing this kiln again until repaired!




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