Jump to content


Photo
- - - - -

three levels of my kiln are firing at different temps


  • Please log in to reply
22 replies to this topic

#1 missholly

missholly

    Advanced Member

  • Members
  • PipPipPip
  • 177 posts
  • Locationzanesville, ohio

Posted 02 October 2012 - 04:44 PM

is the only way to fix this changing out the elements?
www.lotsapotsa.com
www.daddyzero.com

#2 armen

armen

    Member

  • Members
  • PipPip
  • 24 posts

Posted 02 October 2012 - 04:50 PM

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.




#3 Arnold Howard

Arnold Howard

    Graduate, School of Life

  • Members
  • PipPipPip
  • 229 posts
  • LocationMesquite, Texas USA

Posted 02 October 2012 - 05:00 PM

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

#4 icyone

icyone

    Advanced Member

  • Members
  • PipPipPip
  • 65 posts

Posted 02 October 2012 - 11:00 PM

I had similar problem till I got a kiln vent

#5 missholly

missholly

    Advanced Member

  • Members
  • PipPipPip
  • 177 posts
  • Locationzanesville, ohio

Posted 03 October 2012 - 10:14 AM

Is that a top loading kiln?

yes, its a gare 1822.

What cone is maturing in each kiln section?

this is a 06 fire.

Posted Image

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
[/quote]
www.lotsapotsa.com
www.daddyzero.com

#6 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,145 posts
  • LocationGrayslake, IL

Posted 03 October 2012 - 10:20 AM

Pack it looser at the bottom, tighter in the middle.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#7 Arnold Howard

Arnold Howard

    Graduate, School of Life

  • Members
  • PipPipPip
  • 229 posts
  • LocationMesquite, Texas USA

Posted 03 October 2012 - 10:38 AM

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

#8 Mark McCombs

Mark McCombs

    Advanced Member

  • Members
  • PipPipPip
  • 121 posts
  • LocationSW Washington

Posted 03 October 2012 - 10:50 AM

Have you verified that all of the elements in the kiln are working correctly?
Mark
Fast Hawk Pottery


^5-6 Ox
1227 Skutt

#9 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,145 posts
  • LocationGrayslake, IL

Posted 03 October 2012 - 12:44 PM


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.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#10 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,145 posts
  • LocationGrayslake, IL

Posted 03 October 2012 - 12:47 PM

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.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#11 perkolator

perkolator

    Advanced Member

  • Members
  • PipPipPip
  • 278 posts
  • LocationCalifornia

Posted 04 October 2012 - 07:43 PM

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.

#12 missholly

missholly

    Advanced Member

  • Members
  • PipPipPip
  • 177 posts
  • Locationzanesville, ohio

Posted 09 October 2012 - 05:00 PM

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.
www.lotsapotsa.com
www.daddyzero.com

#13 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,145 posts
  • LocationGrayslake, IL

Posted 09 October 2012 - 07:49 PM

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.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#14 Isculpt

Isculpt

    Inexperienced but eager

  • Members
  • PipPipPip
  • 290 posts

Posted 09 October 2012 - 10:11 PM


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?

#15 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,145 posts
  • LocationGrayslake, IL

Posted 10 October 2012 - 09:15 AM



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.
Neil Estrick
Kiln Repair Tech
L&L Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com

#16 Arnold Howard

Arnold Howard

    Graduate, School of Life

  • Members
  • PipPipPip
  • 229 posts
  • LocationMesquite, Texas USA

Posted 10 October 2012 - 10:01 AM

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

#17 DAY

DAY

    Advanced Member

  • Members
  • PipPipPip
  • 160 posts

Posted 11 October 2012 - 05:38 AM

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.

#18 Lucille Oka

Lucille Oka

    Advanced Member

  • Members
  • PipPipPip
  • 756 posts
  • LocationCalifornia

Posted 11 October 2012 - 06:49 AM

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.


John 3:16
"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".

#19 JBaymore

JBaymore

    Moderator

  • Moderators
  • 2,457 posts
  • LocationWilton, NH USA

Posted 11 October 2012 - 12:29 PM

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 Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#20 missholly

missholly

    Advanced Member

  • Members
  • PipPipPip
  • 177 posts
  • Locationzanesville, ohio

Posted 11 October 2012 - 01:15 PM

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!
www.lotsapotsa.com
www.daddyzero.com




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users