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Firing Error


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#1 Pittypat

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Posted 04 November 2012 - 07:55 AM

When I set the firing info into my electric kiln for firing greenwre, I was apparently badly distracted, as I failed to change from the last setting of cone 5....my intention was to fire at 04. When I checked my kiln, which should have been cooling off, I had a message of FTH.............AND I assumed the worst.........I immediately turned the power off to the kiln, and waited 24 hours to allow cooling. Apparently the kiln had held and not begu
n the cooling off process......

I had no idea what I would find when I finally, in fear, opened the kiln. I did find very discolored (yellowish brown) pots. WOW...after 3 years of owning my kiln, I thought I was beyond such stupidity.

What can I do with these pots? Can they be glazed and fired, or should I discard all and chalk this large kiln full of beautiful (ruined?) ware to a very bad experience. Also, what about my beautiful kiln.....have I possibly damaged it? My kiln is a Paragon with a Sentry 2.0 digital temperature controller.

A hobby turned in to a disaster. Please help......also, make me feel better by telling me someone else has been similarly distracted.

#2 bciskepottery

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Posted 04 November 2012 - 09:40 AM

No, you're not the first to have this experience nor will you be the last. Distractions happen -- even to the most experienced kiln firers. It's just clay and there is plenty more where that came.

Sounds like the wares are overfired. What type of clay body were you using -- one that vitrifies at Cone 5/6 or higher? And, at vitrification, how absorbent is the clay -- less than 1%, 2%, 4%? That will dictate, to a large extent, whether or not you could easily and successfully glaze the items.

#3 Pittypat

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Posted 04 November 2012 - 09:56 AM

No, you're not the first to have this experience nor will you be the last. Distractions happen -- even to the most experienced kiln firers. It's just clay and there is plenty more where that came.

Sounds like the wares are overfired. What type of clay body were you using -- one that vitrifies at Cone 5/6 or higher? And, at vitrification, how absorbent is the clay -- less than 1%, 2%, 4%? That will dictate, to a large extent, whether or not you could easily and successfully glaze the items.



#4 Pittypat

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Posted 04 November 2012 - 10:00 AM

The Clay is Trinity Cone 6, though I successfully fire at cone 5.(this is based on a friend's recommendation, a full-time potter who has used this clay for many years). I don't know about the absorbancy. I presume I can find that information on their web site, where would the preference percentage be?

#5 bciskepottery

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Posted 04 November 2012 - 11:03 AM

Their website should provide, for each clay sold, the cone range, shrinkage, absorbency, and an MSDS. I could not find these on the Trinity website; so, you may have to call them and get the info.

For functional ware, I prefer an absorbency of 2% of less.

#6 Marcia Selsor

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Posted 05 November 2012 - 07:44 AM

Your biggest problem will be to get a glaze on to the surface. Heating the pieces helps. Use thicker glaze helps but pay attention you don't get it on too thick doing it this way.
The pieces shouls be salvageable. Not a complete loss...just more work for you.
It does happen. You are not alone there.
Best wishes,
Marcia

#7 Pittypat

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Posted 05 November 2012 - 11:00 AM

Their website should provide, for each clay sold, the cone range, shrinkage, absorbency, and an MSDS. I could not find these on the Trinity website; so, you may have to call them and get the info.

For functional ware, I prefer an absorbency of 2% of less.



#8 Pittypat

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Posted 05 November 2012 - 11:02 AM

All I could get from Trinity is that the absorbancy is going to be less than 1/%. They suggested warming the clay to no more than 200 degrees before glazing.......guess that is worth a try.

thanks for your help.
Pat




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