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How Long To Reach Cone 9? Is It My Kiln?


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Hi there! I'm new here and a (relatively) rookie potter as well. Been throwing for a year but just built my own studio at home. This is my first go at firing my own work.

 

I bought a used Skutt 1027 (kiln sitter version) and have successfully bisquefired to 06 and 04. I know not to attempt high fire 9/10 often bc it's hard on the kiln, but I'm trying to work through some cone 10 clay I bought before I knew that. 😊

 

I began firing the day before yesterday and set the shut off for 9 hours and went to sleep only to find the sitter still locked. So up I went again this time firing for 11 hours and still, the sitter is in place. I ended up adding an additional 5 hours before bed and just found the sitter still in place.

 

Can it take this long to get to cone 9? I had the proper electrical (240) ran to the kiln. Do I turn it back on again? Is my work ruined? Do I let it cool and see? How long should I wait if I do that?

 

Sorry for the long post! All advice is welcomed and very much appreciated! Of course there are Mother's Day gifts inside 😢

 

Thanks, Alli

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My guess is the elements are old. It will take longer than you have tried and I suggest you either try to keep going(more hours staying up) Without a pyrometer you are firing blind or give it up and replace the elements. Ether way let the kiln cool until its about 200-300 degrees. You should have a pyrometer installed to know this.Or wait 12 -25 hours.

I never have fired to cone 10 in an electric in my 44 years of pottery work.

Neil should weigh in here and tell you more about element testing.

I have to leave right now for a show.

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Could be any number of issues. If any one part of the kiln isn't working then it won't get to temperature. Could be the elements are worn, or one is broken. Could be a fried wiring connection. Could be a switch is fried. Could be a problem with the sitter. The first basic test you should do is turn each section on high one at a time starting at the bottom and carefully put a piece of paper up to each element once they start to heat a bit and see if the paper burns. If they all burn, then they're probably worn out. If one doesn't burn, then that element is fried or there's a problem in the wiring. If a pair of elements in the same ring don't burn, then there's a wiring problem or the switch is burned out. There are other possibilities but this covers the most likely issues.

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Thanks guys!

 

Just for clarification, wouldn't the paper burning be a good thing? What would the ideal situation be with the paper test? I'm so new to this.

 

So... are we saying this current load is a lost cause?

 

Also, I only paid 300 for the kiln (had to buy all new furniture, too) is it worth investing in to get her up to par or should I sell it and move on? Tempted to finance a new one.

 

Really appreciate the time and wisdom!

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My money is on a burnt element.

 

"If they all burn, then they're probably worn out." This I suspect might be a moment of dyslexia - if not I'm confused as well.

 

If the kiln is older but still in good shape as far as the fire brick goes it is definitely worth some love.

 

I'm no electrician but I do know the switches and relays that make an electric kiln run are relatively simple to work on and cheap to replace. A qualified/experienced kiln tech/electrician type person will be able to fix the control board easily if necessary.

 

Those elements are probably tired and on their way out. iirc they cost about 50$ each and will set you up for another 40+ firings. The are not much fun to remove and replace but with some good side-cutters and needle-nose the job can be done in an afternoon.

 

It sounds like your relays are still 'clicking' on and off? afaik relays will fail in one of two positiions - on or off. On is bad and will cause a runaway and is one of the reasons to never turn your back on a kiln near the end of it's firing.

 

hope this helps a bit

 

 

 

 

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I'm no electrician but I do know the switches and relays that make an electric kiln run are relatively simple to work on and cheap to replace. A qualified/experienced kiln tech/electrician type person will be able to fix the control board easily if necessary.

This kiln has a kiln sitter, there are no relays or control board. If it is a fried switch, one of those costs $85.

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So, I'm still firing away. It dawned on me - my top peep hole has been left open the entire time. I thought I was never to close it, so I didn't buy one for the top. I had an old one made of fire brick that belongs to an ancient Paradigm kiln in my garage (long story), and just plugged it up and added more time. 

 

Could this be why it's not reaching temperature? We are well past the venting stage... 

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A kiln with worn out elements, or one or more elements broken or otherwise failed because of broken switches or wires, is capable of reaching bisque/low fire temperatures despite the partial failure. However, it will not be able to produce the heat necessary to reach even mid-fire (cone 6), much less cone 9-10. It will just stall because the continuous minor heat losses through the shell can barely be replaced by the failing elements.

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I'm no electrician but I do know the switches and relays that make an electric kiln run are relatively simple to work on and cheap to replace. A qualified/experienced kiln tech/electrician type person will be able to fix the control board easily if necessary.

This kiln has a kiln sitter, there are no relays or control board. If it is a fried switch, one of those costs $85.

 

ugh

 

:)

 

I should stick to lurking

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So, I'm still firing away. It dawned on me - my top peep hole has been left open the entire time. I thought I was never to close it, so I didn't buy one for the top. I had an old one made of fire brick that belongs to an ancient Paradigm kiln in my garage (long story), and just plugged it up and added more time. 

 

Could this be why it's not reaching temperature? We are well past the venting stage... 

 

You need to fix something. The kiln is firing way too long.

 

*I sometimes have issues with reading comprehension obviously but electric kilns should never fire for days in a row.

 

You need to turn it off and trouble shoot the elements/electronics.

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Ok. Calling it quits. Can I finish firing the pieces at a later time or are they ruined now?

There has been a lot of heat-work done.

 

Generally speaking an undefired kiln can be refired with good success.

 

It's unfortunate timing for your Mums day pots.

 

This will be a good learning experience though - Goodness knows we have all had a few.

 

*you may already be aware of the Orton chart: http://www.sheffield-pottery.com/v/vspfiles/downloadables/cone_wall_chart_horiz.pdf

 

The section in the lower right that explains a bit about the idea of heat over time may not be the most comforting at this point but it helped me  understand how heat works.

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If all of the elements can burn paper, then there's not a broken element or problem with the wiring or switches. However, since they're all working but it can't get to temperature, then the elements are worn out. They heat up, but not enough.

 

Ok that makes sense. 

 

How long will it take to cool to the point of unloading without damaging the pots any further? 

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