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under fire bisque


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#1 pamelag

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Posted 16 November 2012 - 01:39 AM

My kiln was to turn off at cone 04 with the kiln sitter, But instead it turned off within 5 hours. My question is, can I refire the bisque to reach 04 just as if it were firing for the first time? I just hope I didn't ruin my pottery. Thank You for your reply

#2 oldlady

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Posted 16 November 2012 - 02:36 AM

yes, just fire it again.

why did it go off in 5 hours, does your sitter have a timer and you neglected to put enough time on it? was the cone in the sitter bent at all? more info would help the real experts here help you.
"putting you down does not raise me up."

#3 Marcia Selsor

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Posted 16 November 2012 - 02:27 PM

If you had a witness cone in there , you might know whether or not you reached ^04.
It is always a good idea to use witness cones, but of course we trust our kilns.

Marcia

#4 pamelag

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Posted 16 November 2012 - 04:34 PM

Yes the cone did bend but very little and it does have a timer. I didn't realize my husband set the timer for 5 hrs. And honestly I have just gotten this kiln and I am not to sure on how to work it nor how long the firing process will take for the greenware to fire to cone 04. Is been a long time since I had a kiln in the early 70"s. And I don't recall how I did it back then! And haven"t found much on the internet that tells you how long it takes. But in my search I found this site.
I did restart it at 12:39 pm with the cone in the sitter and a wittiness cone and I set the timer to 17 hours. Is this enough time? And thank you for your reply

#5 OffCenter

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Posted 16 November 2012 - 06:42 PM

If 04 bent at all and assuming there is no special reason for going to 04, such as solving pinhole problems with glazes, your pots have been fired high enough for a bisque and re-firing them will just be a waste of time and electricity. 04 is a little on the high side for bisque firing, anyway. The only clay I bisque over 012 is Lizella Red which needs to be bisqued higher to avoid pinholes in the glaze.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#6 oldlady

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Posted 17 November 2012 - 12:42 AM

OK, more info helps. since it is an electric kiln there is a manufacturers name somewhere on it. if it is an older one, you can find out the firing directions that particular company gives out to owners by contacting them directly. it is always better to talk to the people who know the most. find their phone number on the internet, but TALK to someone in their technical section on a phone. tell them ALL the information you find printed on the kiln and measure it's depth and width, inside, just in case you cannot find much. they should be willing to send you written info once you have talked to them. maybe there is a small cost but find out.

yes, these forums are great but we all have different experiences. i have never had a timer on a kiln sitter until one i was given a couple of years ago. it still makes no sense to me but i have it written down in that studio and refer to it when i fire that kiln. that is why i suggested the possibility that the timer was set wrong. i've done that. once was enough.

is the "cone" in your sitter a pyrometric bar with four sides all the same or is it an actual cone that tapers? something else to consider.

have fun with your kiln and happy potting.
"putting you down does not raise me up."

#7 clayshapes

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Posted 17 November 2012 - 04:12 AM

My kiln fires to 04 in 6 hours, (I know this from experience) so I set my timer for 7 hours, with a kiln sitter and cones on two shelves. Your kiln may be different == but 17 hours is likely WAY too long. But no harm as along as you keep watch, and your kiln sitter works. If your sitter doesn't turn the kiln off after 6 hours, turn it off yourself and see where the cones are inside the kiln. When you have a kiln that's new to you, you have to expect to experiment a little. Of course, depending on how you load the kiln, there will be a lot of trial and error. That's why it's important your kiln sitter is working properly.
I agree though that 04 is a bit high for bisque. I try to fire to 05 for my bisque and glaze to cone 6 (for stoneware, that is!) You didn't mention what kind of clay you are using -- earthenware or stoneware? I fire to 04 bisque, and 05 for glaze on earthenware. But you should ask whoever sold you the clay what cone to fire to, as clay bodies are all a little different.

#8 Lucille Oka

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Posted 17 November 2012 - 06:18 AM

The most informative 'Operating Manuals' I have ever encountered comes from Skutt Kilns.
Measure your kiln if you don't already know the dimensions. Find the Skutt Kiln that comes close in dimensions and maximum firing temperature and you will find a lot of information on how to fire your kiln. http://www.skutt.com...Manual_2002.pdf

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"For God so loved the world that He gave His only begotten Son, that whosoever believeth in Him should not perish but have everlasting life".




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