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mygvsuccess

Kiln Melted Everything @ Cone 03

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mygvsuccess    0

I fired my kiln last night same as I have been for the last 2+ years to cone 03 usually takes about 7.26 hours, half way through I went to check the kiln and the orton sentry xpress control board displayed CPLT @ 4.11 it was still at 1400 degrees F so I waited til this morning to open it and 4 shelves of beads and pendants were completely melted i mean gone! a giant blob of glass 4 shelves deep I dont understand what happened, I fired the same as always, the control bored should have gave me an error message if it got too hot, my question is could my work have melted like this not because it got too hot but because it reached temperature twice as fast as normal?? a few months back i woke up to a kiln load of glazed ware that didnt finish fring the display read HTDE Heat temperature deviation kiln shut off because relay got stuck or something, i never figured it out i refired and watched the kiln and it worked without issue until today, and one more thing to add is that if the relay was stuck bridged than i would have had to physically shut off the kiln would have still been hot but the kiln read Completed after just 4 hours also the control bored would give an error if it overheated, I cant let this happen again, paragon wants to send replacement parts but i want to know what the problem even is, they said replace the control bored and the relay but why? which is it and what happened, did my kiln furniture and jewelry all melt because it fired too fast or did my kiln get too hot and somehow bypass showing an error message? and once again as far as it appears kiln seems to be working again thanks for any help!

 

P.s. I attached images to see what happened to my high fire kiln shelves when fired to cone 03 in 4 hours and 11min

 

post-19161-0-22017900-1500437690_thumb.jpg

post-19161-0-02378400-1500437706_thumb.jpg

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mygvsuccess    0

thanks for your reply Neil, My relay is a dual relay the newer ones I thought that was supposed to prevent from bridging unless both failed at same time which is very unlikely? Also this happened in 4 hours, could the kiln really have reached max temp of 2300-2400 in just 4 hours ? by the time i checked it must have been right after it "completed" the temp was already down to 1440 F I cant believe it cooled from 2400 to 1440 in just an hour all of this happened within a 5 hour total period, you dont think this could happen from heating up twice as fast as normal? or would you say absolutely my kiln had to overfire to do this to ceramics? Also thermocouple was just replaced 2 months ago because i did have a bad one but this one has been working great and is in excellent condition still

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Min    783

your melt down isn't from firing too fast, as Neil said you fired too hot. do you use a preset firing profile or enter your own? if it's the latter could you post it?

also, what clay and glaze are you using, cone? how big is your kiln? small kilns can drop really fast. Guessing you don't use witness cones?

 

edit: "high fire" means different things depending on your source of information. Places that sell mostly bisqueware for low firing and readymade glazes etc will call highfire cone 6. Pottery supply places will call highfire cone 10 and up. If your shelves are from a place like the first one then what they are saying are highfire shelves are likely rated for midrange temps like cone 6. They don't look like highfire cone 10+ shelves. Same thing for glazes.

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neilestrick    1,381

thanks for your reply Neil, My relay is a dual relay the newer ones I thought that was supposed to prevent from bridging unless both failed at same time which is very unlikely? Also this happened in 4 hours, could the kiln really have reached max temp of 2300-2400 in just 4 hours ? by the time i checked it must have been right after it "completed" the temp was already down to 1440 F I cant believe it cooled from 2400 to 1440 in just an hour all of this happened within a 5 hour total period, you dont think this could happen from heating up twice as fast as normal? or would you say absolutely my kiln had to overfire to do this to ceramics? Also thermocouple was just replaced 2 months ago because i did have a bad one but this one has been working great and is in excellent condition still

 

If a relay sticks in the 'on' position, it will allow full power to the elements until it decides to unstick itself (if at all). Since your kiln did cool down, the relay definitely unstuck itself.

 

Clearly the kiln reached much higher temps than it was supposedly programmed to. Yes, a small kiln can reach high temps very quickly. As to whether or not it got to 2300, only the controller could tell you that. Low fire white clay will puddle by cone 3. What was the temperature rating if the furniture that deformed? Did you do a review at the end of the firing to see how hot it got?

 

Yes, the kiln could cool that much in an hour, especially a small kiln.

 

Check your thermocouples.

 

The other option is that it was programmed wrong. It's very common. Do a review on the controller and see what the program was.

 

Ultimately, the only thing that can keep a kiln from over-firing is you. Regardless of how many safety systems there are on the kiln, they all have the possibility of failing. Since you're doing low fire work, and doing it in a small kiln, the possibility of over-firing is much, much greater than for those of us working at cone 6 in big kilns.

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Denice    243

The only time I fire a kiln at night is when I have a sculpture in it and I candle it overnight before I fire it in the morning.  None of my kilns have computers,  I just recently rebuilt my 35 year old Skutt,  my husband wanted me to buy a computerized kiln.  I told him my Skutt is like a old friend I know exactly how to fire it.  I had a pottery teacher that over fired a manual kiln in high school, it didn't even have a kiln sitter.  In the morning he realized he has forgotten to turn it off, his pots were melted into puddles.  The high fire shelves had glaze stuck to them but they were in good condition otherwise.  A bad firing can happen to anyone.  Denice

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