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Kristina Vatne

Kilnsitter stopped firing, witness cone not bent

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We recently did a test firing of some cone 6 clays in our old-time Skutt kiln (model 1081 or 181?) to cone 04. The pyrometric bar in the kilnsitter melted to a perfect u/v shape & turned off the kiln, but the 04 witness cone we placed near our test tiles apparently didn't melt at all. Also, the test tiles in this kiln sound less bell-like when we tap them against each other than the ones in our Skutt 818 programmable kiln.

1) How do you tell when a piece is completely bisqued?

2) (Assuming our test tiles really aren't completely bisqued like I think they probably aren't), what should we do to be sure the kiln is doing enough heat work? Should we put 03 bars in the kilnsitter?

I'm a tolerably experienced potter, but a total newbie at firing, so any and all advice from those of you with more experience will be very much appreciated.

Thank you,
-Kristina Vatne

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Oh, there is a little metal disc you put in the pointy end and then adjust the weight in the front end.  It's in the manual for the kiln sitter model you have.  I think a lot of people just toss out the calibration "plate", or lose it, so if it was a used kiln, might need to order one from your local pottery supply.

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If the cone is bending to a perfect 90 degrees, but it's not accurate, there's a good chance the sitter rod (the rod that sits on top of the cone and has the claw at the other end)) is bent or worn away. Take a look at it where it rests on the cone and see if it tapers at the end from burning away over the years. To check if it's bent (also from wear), take off the cover plate from the front of the sitter and rotate the claw and rod and you can see if it rotates evenly. If either issue is present, replace the rod.

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...I like th' idea painting a thin line of iron oxide on the cone t'make it easier to see. Not sure who posted that now ...was it Min? Any road, it helps ...'nother helpful hint, stand up the cone packs so they are level with (in front of) the peepholes; I cut thrown tube into the needed heights and fix a lil' slab onto them...

Recall to wear the appropriate protective glasses!! !!!

From Bailey website: "Infrared glasses are imperative when looking into kiln spy holes. These protect your eyes from the radiant heat. (Please note that regular sunglasses are inadequate for this purpose and may actually melt.) Protective glasses may also allow you to see your cone packs more clearly."

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47 minutes ago, Hulk said:

...I like th' idea painting a thin line of iron oxide on the cone t'make it easier to see. Not sure who posted that now ...was it Min? Any road, it helps ...'nother helpful hint, stand up the cone packs so they are level with (in front of) the peepholes; I cut thrown tube into the needed heights and fix a lil' slab onto them...

Recall to wear the appropriate protective glasses!! !!!

From Bailey website: "Infrared glasses are imperative when looking into kiln spy holes. These protect your eyes from the radiant heat. (Please note that regular sunglasses are inadequate for this purpose and may actually melt.) Protective glasses may also allow you to see your cone packs more clearly."

Welders goggles with a #4 lens work great, you can see cones clearly in oxidation

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