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Being a less-than-tall person,  I bought an L&L  18" deep kiln - I couldn't reach the bottom of the 27â€ers.   Kiln works great, tho I have to add degrees  to the cone offset for 04 bisquing,  and remove some from cone 6, ( according to my witness cones).  Actually right now I’m using the cone 5 setting and that seems to get my 6 cone to the right spot. 


 


My e28s has 4 elements and 2 thermocouples, and this creates some challenges.


 


I get even responses from my witness cones only if I fire with only 2 shelves.  With 3 shelves in, the witness cones vary widely.  I’ve tried every variation on shelf placement I can think of, including staggering and using 2 1/2 half shelves.  The manufacturer says that you need 2 elements and 1 thermocouple per  shelf, and I’m pretty sure I also read that the shelves should clear the elements. With my kiln , that means you can only have 2 shelves in, and when I follow these guidelines the kiln gods do favor me with matching witness cones.  


 


This has all turned out not to be a big problem for me anyway, because I haven’t had as much time as I’d hoped I would to be making stuff.  Also running the kiln seems to cost me only about $10 a month for  3-4 firings.  I expected the cost to be much higher.   I'm making less at one time, but also getting more instant gratification,  (instant being a relative term when applied to a slowly cooling kiln).


 


Should I be less concerned about matching cones?  I assume it's a matter of degree.  It can be more than 1 cone.


 


Also, I have been "lidding" the load with the 2 unused half shelves  because I feel I should have them in there to increase the thermal mass, which is already 1/3 less than what the kiln could hold.    Any thoughts on that?


 


Thank you in advance for your advice and experience


Irene in NJ


 




 


 


 


 


 


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In what way is it uneven? Top to bottom? Center to edges? One side vs the other?

 

Half a cone difference isn't a big deal at all, so don't worry about that. Your kiln will fire more evenly if it's packed full. Firing slower will also help, as it gives the heat time to radiate around. Do you have a shelf at the bottom, 1/2-1" up from the floor? That will help with keeping the bottom from running cold. General rules with all kilns: always load bigger pieces at the bottom. Don't pack it tight down there will small pieces as it's the most likely place to run cold. Don't do a short shelf at the top or it's likely to run cold there due to heat loss out the lid.

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I have a shelf 1/2" off the bottom.  Actually the bottom of my kiln runs warmer than the top, another reason I put the extra shelf on top. Maybe I was running it with 1 element in the top shelf and that's why it was cooler.

 

I've fired with a set of cones on each half shelf, so 6 sets of cones,  and unfortunately the cone difference can be more than 1 in a shelf with only 1 element and no thermocouple.  I try to put the cones in the center of each half sheet.  Have you run across this before?  I use the slow glaze cycle exclusively, and a 15 or 20 minute hold at the end.  My kiln with 3 shelves of pots in any configuration doesn't have even witness cones. I've tried having a half shelf at the center of a full shelf that has 2 elements, thinking the heat will migrate over but it hasn't helped.  Do I need a longer hold?  Slower cool down?

 

Do you think I need to program a slower glaze?  The same unevenness happens in the bisque, but I've stopped using dark clay and it doesn't seem to matter now, in terms of pinholing I mean.  I'll remember that about bigger pieces at the bottom tho.

 

How close to the recommended glaze cone do I have to be in terms of vitrification?  Is that the right term?

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I haven't run into this before. Check your thermocouples to make sure they're touching the ends of the protection tubes. I would completely remove them and dump out any bits in the tube, too. Once you're reinstalled them, push the the thermocouples in to the ends of the tubes before tightening the screws that hold them in the block.

 

I would think that the slow glaze with a hold should be slow enough, especially with the hold.

 

Have you checked that you're getting a full 240 volts from your service?

 

Are your elements in good condition?

 

Does it do any better with a really full load?

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It says it's reading both thermocouples, but maybe it isn't.  Is there a way to check that?

 

I'll check them out see if there's any debris in them, and be sure they're touching the ends of the tubes.  They look like they're in good shape, and I've never whacked either of them with a shelf or anything.  I've fired the kiln about 50 times.  

 

How can i tell if I'm getting all 240 volts?  It was  wired by an electrician a year ago when I got the kiln, and I still have room in the breaker box for more stuff.

 

Thanks for the ideas.   I'm going to read up on how to remove the thermocouple tubes now.

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