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Skutt KS kiln overheating


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#1 Maddriel

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Posted 09 November 2012 - 08:31 PM

Hi All,
I have a firing problem and I wonder if anyone can help me. I have a Skutt KS 1027-3 that is probably 15 yrs old. (I work in a school environment) It has a kiln sitter (LT-3 or LT-3K, I am not in the studio and can't remember!) During the last two bisque firings (I have not tried a glaze firing in this kiln recently) the kiln has overheated, going well beyond 05 - probably more into the 6 range! Bisque pieces are coming out well vitrified, we use a mid-range clay and the pieces have a sheen on the surface in spots. The kiln sitter bar melted and the kiln did not trip. The first time it happened, I made sure the sensing rod was moving freely and replaced the rests, using a coat of kiln wash just in case. I then fired the kiln with just posts, shelves and witness cones. During this firing the kiln performed fine. I then loaded up the next bisque load (kept it relatively light, we do have some heavier sculptures, but I kept it sparse-r), held my breath and fired again. Again, the kiln overfired, the bar had melted. Thank goodness for timers! The witness cones I put in (05 and 04) were black puddles on the shelves. This kiln had the elements replaced late last school year, top to bottom, but it doesn't seem that it would be an element issue. The kiln seems to be heating up just fine, it's the shutting off part that is the problem!
Thanks in advance for any ideas!

#2 neilestrick

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Posted 10 November 2012 - 08:41 AM

Sounds like there may be some corrosion in the sitter mechanism, or the sensing rod is bent. Take the whole thing out and check for corrosion. If the rod tapers down at the end or is bent, it should be replaced. Check the calibration of the sitter as well.

Does your sitter have a timer?
Neil Estrick
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Owner, Neil Estrick Gallery, LLC
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neil@neilestrickgallery.com

#3 Lucille Oka

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Posted 10 November 2012 - 09:41 PM

Reading your post I am wondering about the loading of the kiln. You said that you did an empty firing and it was fine. Make sure that you are not loading ware too close to the KilnSitter. Keep all ware away from the Sitter at least 2".

Do not allow anything to touch any part of the mechanism; and don't allow your pyrometric cones to be too close to the Sitter as well.

Finally check the pyrometric cone numbers to be sure they are correct. If you need to, get a magnifying glass to help you read the numbers.

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