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missholly

three levels of my kiln are firing at different temps

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is the only way to fix this changing out the elements?

 

 

I know nothing about kiln management, but I would think that a way to check if the elements are the problem is to switch the elements around and see if the changes change. Like if your elements are arranged A, B, C, top to bottom, and fire to cones 3, 4, 5, respectively, and you switch them to be B, C, A, and you see that it now fires to cones 4, 5, 3, you'd know that the elements are causing the difference.

 

 

 

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is the only way to fix this changing out the elements?

 

 

Is that a top loading kiln?

 

What cone is maturing in each kiln section?

 

Has this happened before?

 

To a certain extent, you can adjust the temperature of each kiln section by rearranging the density of the load. Place more ware in hot sections of the kiln and less ware in cool sections. Sometimes the problem is caused by a lid that rises half an inch or so at high temperatures. Leaving the peephole plugs out when firing with a downdraft vent will also cause the kiln to fire unevenly.

 

Sincerely,

 

Arnold Howard

Paragon Industries, L.P., Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

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Is that a top loading kiln?

 

yes, its a gare 1822.

 

What cone is maturing in each kiln section?

 

this is a 06 fire.

 

photo2copy.jpg

 

Has this happened before?

 

not that i know of. I've had the kiln for about two years and just noticed the severity of the issue.

 

To a certain extent, you can adjust the temperature of each kiln section by rearranging the density of the load. Place more ware in hot sections of the kiln and less ware in cool sections. Sometimes the problem is caused by a lid that rises half an inch or so at high temperatures. Leaving the peephole plugs out when firing with a downdraft vent will also cause the kiln to fire unevenly.

 

im bisquing at 05 and glazing at 06. the glaze fire is really when i see the difference. my underglaze colors differ immensely between the bottom and middle shelves.

I'm pretty sure the lid isn't rising at all throughout the firing. i don't have a vent and i fire right beside an open door to the outside. (this was also something i was wondering about as far as when the weather gets colder) i usually only open the door if its nice outside or if i can really smell the kiln burning. top peephole open, bottom closed.

 

Sincerely,

 

Arnold Howard

Paragon Industries, L.P., Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

 

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Pack it looser at the bottom, tighter in the middle.

 

 

I agree. The heat distribution should be easy to correct with the above advice. I'm glad you use witness cones. That simplifies troubleshooting.

 

Sincerely,

 

Arnold Howard

Paragon Industries, L.P., Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

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is the only way to fix this changing out the elements?

 

 

I know nothing about kiln management, but I would think that a way to check if the elements are the problem is to switch the elements around and see if the changes change. Like if your elements are arranged A, B, C, top to bottom, and fire to cones 3, 4, 5, respectively, and you switch them to be B, C, A, and you see that it now fires to cones 4, 5, 3, you'd know that the elements are causing the difference.

 

 

 

 

 

This seems logical, but switching around elements is a whole lot of work, and impossible in some kilns. You'll likely end up breaking an element.

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Have you verified that all of the elements in the kiln are working correctly?

 

 

Since the cone at the bottom is starting to bend, most likely they are fine. It's worth a check on the bottom ring, though, just to make sure. Depending on the kiln, it may still get to bisque temp with one element out. Put a small piece of paper on each element and start the kiln for a few minutes. Turn off the kiln and see if the paper has burned.

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Put a small piece of paper on each element and start the kiln for a few minutes. Turn off the kiln and see if the paper has burned.

 

 

ooh, i like that little trick! gonna have to use this next time! much better than my usual way of cranking an empty kiln on and waiting till about 800* when the elements start to glow, and crack the kiln slightly to look inside.

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all of the elements are working.

i get the point of the load distribution, but id really rather get the levels at an equal temp.

trying to redistribute the load and taking a chance on things still not firing right is going to lose me alot of pieces not to mention alot of available space inside the kiln.

 

im so frusrated, i dont even want to fire anymore.

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all of the elements are working.

i get the point of the load distribution, but id really rather get the levels at an equal temp.

trying to redistribute the load and taking a chance on things still not firing right is going to lose me alot of pieces not to mention alot of available space inside the kiln.

 

im so frusrated, i dont even want to fire anymore.

 

 

Unless the elements at the top/bottom are worn and not firing as hot as they should, the way you stack the kiln is the only way to solve the problem. This is normal for all kilns that do not have zone control. To compensate for the difference in heat at the top/bottom compared to the middle, many brands have 'graded' elements that run hotter at the top and bottom. This does a pretty good job of evening it out, but is still not perfect. In gas kilns, adjustments can be made with the burners and damper to deal with unevenness. In an electric kiln, it's the stack.

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Have you verified that all of the elements in the kiln are working correctly?

 

 

Since the cone at the bottom is starting to bend, most likely they are fine. It's worth a check on the bottom ring, though, just to make sure. Depending on the kiln, it may still get to bisque temp with one element out. Put a small piece of paper on each element and start the kiln for a few minutes. Turn off the kiln and see if the paper has burned.

 

 

Thanks for this easy diagnostic tool! I can't wait to try it tomorrow. After posting a few days ago, looking to find an easy route to a shorter firing schedule (yeah I finally get that there is no such thing as one-size-fits-all), I loaded my kiln, turned it on, and found that 2 of the three elements are either not working or barely working. (This was a Really short firing schedule (lol)-- ! ) The kiln has been sitting under plastic on the studio porch for 6 months while the studio was gutted and remodeled. It is an old top loader, but it was working fine when I moved it to the porch. Any thoughts?

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Have you verified that all of the elements in the kiln are working correctly?

 

 

Since the cone at the bottom is starting to bend, most likely they are fine. It's worth a check on the bottom ring, though, just to make sure. Depending on the kiln, it may still get to bisque temp with one element out. Put a small piece of paper on each element and start the kiln for a few minutes. Turn off the kiln and see if the paper has burned.

 

 

Thanks for this easy diagnostic tool! I can't wait to try it tomorrow. After posting a few days ago, looking to find an easy route to a shorter firing schedule (yeah I finally get that there is no such thing as one-size-fits-all), I loaded my kiln, turned it on, and found that 2 of the three elements are either not working or barely working. (This was a Really short firing schedule (lol)-- ! ) The kiln has been sitting under plastic on the studio porch for 6 months while the studio was gutted and remodeled. It is an old top loader, but it was working fine when I moved it to the porch. Any thoughts?

 

 

It's possible that a connection came loose when it was moved, or something corroded while sitting under the plastic. You'll have to open up the panel and take a look.

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I loaded my kiln, turned it on, and found that 2 of the three elements are either not working or barely working.

 

In some models, the center elements do not glow brightly--even at cone 7. This is because the center elements produce less heat than the top and bottom elements. This may be the case with your kiln.

 

Sincerely,

 

Arnold Howard

Paragon Industries, L.P., Mesquite, Texas USA

ahoward@paragonweb.com / www.paragonweb.com

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Like people, elements slow down as they age. If one burns out and is replaced, it will work harder that the old timers. That is why it is recommended to replace all elements at the same time. Of course, many of us cheapskates don't.

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If the elements were changed, check and see that they were replaced properly. Some kiln manufacturers have top, bottom and middle elements for their kilns. For example, if the middle element goes you want to replace it with a middle element. So check with the kiln manufacturer about replacement of the elements.

 

You can also try staggering the load. Instead of full shelves use half shelves and stagger the placement allowing the heat to rise between the levels. So instead of having three shelf levels have five or six levels, instead of four have seven or eight. You can also try using half shelves one inch smaller than the maximum size shelf; thus allowing the heat to rise freely through the kiln. Also for the bottom shelves be sure they are below and/or between the element courses. Place your witness cones on all levels and see what you get. Let us know what the results are.

 

I hope this has been helpful.

 

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Guest JBaymore

Understanding the impacts of loading density is one of the factors that we teach in the kiln disign and operation courses at the college. Adjusting loading density in regions of a kiln of almost any type is not something that is somehow "separate" from firing a kiln,..... nor is it a "workaround"...... it is an integral part of learing to fire kilns.

 

Lacking industruial quality equipment (and even there most of the time), where it is a bit more possible to divorce even-ness of temperature distribution in a unit from the load density (not totally possible), learning how to stack is a part of the process.

 

best,

 

...............john

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whew. ok.

thanks everyone for your advice. i really appreciate it.

i contacted someone at evenheat and they said to test the ohms of each element to see if they need replaced.

ill do that, see what she says, and ill try the redistribution of the load. i probably wont be firing again for a few weeks, but ill test with witness cones and ill

post what happened.

 

thanks again guys, much appreciated!

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Understanding the impacts of loading density is one of the factors that we teach in the kiln disign and operation courses at the college. Adjusting loading density in regions of a kiln of almost any type is not something that is somehow "separate" from firing a kiln,..... nor is it a "workaround"...... it is an integral part of learing to fire kilns.

 

Lacking industruial quality equipment (and even there most of the time), where it is a bit more possible to divorce even-ness of temperature distribution in a unit from the load density (not totally possible), learning how to stack is a part of the process.

 

best,

 

...............john

 

 

John, you just changed my clay life. A year ago I switched to electric fire to stop the "the kiln gods were not smiling on me" complaints. Other potters in my studio are shocked when I now say things like "I made a bad glaze choice on that piece" instead of blaming the humidity on firing day. But I do still have problems with slightly under-fired glaze in the bottom 8 inches and top 5 inches on the kiln. I will stop blaming the kiln and learn to load better. Thank you. -Dawn

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