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I recently ran my very first cone 6 glaze firing in a small, older manual kiln that I inherited (Paragon A-66B).  
 

The cone 6 bar dropped in the kiln sitter as expected, but when I opened it all up the next day, the witness cones I’d placed inside don’t look like the reached the same temp.  The 5 (left) is bent all the way over, but the 6 (middle) is hardly bent at all. The 6 bar that was in the sitter is bent nicely, however. 
 

Pics here: https://imgur.com/gallery/pd3Aao4

 

Does this mean that the kiln didn’t actually get to cone 6? Do kiln sitters ever trip early? I realize that there can be temp differences inside the kiln, but this is a very small one (the interior is just 15” wide by 13” tall) so I find it hard to believe the disparity would be that great in such a small space. Any insights? 
 

 

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Good advice from @liambesaw and @Mark C..  I wonder how you turned up your switches?  When I was firing the HS kilns back in the day, I would turn on the bottom switch to be about 1/4 turn higher than the second switch, and 1/2 turn more than the top switch. This allowed me to get a more even heat in that kiln with some adjustments in the temp. I always used a cone 6 mini cone or bar in the setter, and watched the peeps for heat color compared to a good chart. Firing, even though mechanical/electronic, is really an art where the fireman has to be aware of all of the little nuances of the kiln, the hot spots and the placement of pots. With good notes, and careful observation you will find the quirks of your kiln and make adjustments accordingly.

 

best of luck,

Pres

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@Pres The kiln only has 1 switch (it's super small). I definitely need to try placing another set of cones inside to see if there is a hotter spot near the sitter, though.


  @liambesaw I definitely didn't receive a calibration tool with the kiln, but I'll look it up!  Interesting tip on using a bar one step hotter in the sitter, too.


@Mark C. Yeah, I might try that.  Also debating just shifting my focus to Cone 5 firings instead of 6, as my glazes came out great from this firing anyway.  Is there any real advantage to making Cone 6 work instead? 

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The sitter bar is not "bent nicely." In a properly calibrated sitter, the bar or mini-cone is bent to a 90° angle for the claw on the outside to release the drop plate. Yours is bent less, so it released early. Hence the hard cone 5 not yet cone 6 result. If you don't have one, get a calibration disk and adjust the sitter claw and drop plate. There are uToob videos how to do that.

dw

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3 hours ago, Dick White said:

The sitter bar is not "bent nicely." In a properly calibrated sitter, the bar or mini-cone is bent to a 90° angle for the claw on the outside to release the drop plate. Yours is bent less, so it released early. Hence the hard cone 5 not yet cone 6 result. If you don't have one, get a calibration disk and adjust the sitter claw and drop plate. There are uToob videos how to do that.

dw

Yes you must do this to calabrate the sitter.Its a must do

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Sitter Gauge, or 'calibration disc' shown in place on the sitter.  Around $5 at most pottery supply stores.

If you don't have a kiln-sitter manual, you can find one on the web.  A quick search also turned up this very detailed write-up on how the sitter works, and how to calibrate it, including lots of close-up pic's.

Sitter Guage

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