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HELP! Cone 5 glaze firing going over 16 hours now!


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Hi everyone! I'm having an issue with my electric kiln at home right now. I started a glaze firing at 1am today at a slow temp, and then put it on full blast early this morning at around 8am before I left to work. It is now 5pm and it is still firing. My glaze firings normally take 5 to 6 hours, but due to the large load and some cracking issues I've been having, I thought I would give it a slow initial start. I'm concerned the wares have been in there too long. Should I turn it off or wait until it possibly shuts off at Cone 5? I have a CRESS FX27P with a kiln sitter, I normally use witness cones, but this kiln has been so reliable with the bar that this one time I didn't do it and left the house all day thinking it would be off early in the morning. When I got home at 5pm it was still blasting, so it's been firing for 15 hours. I've done close to about 50 glaze firings already in this kiln. Any advice would be appreciated! Thinking about just shutting it off asap. The kiln isn't making that clicking sound anymore either which is of concern to me too. 


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14 minutes ago, liambesaw said:

If it hasnt hit cone 5 in 15 hours, it never will.  Might be time for new elements?  What temperature was it at when you turned it to high? On high for 9 hours, sounds like it won't get there to me.

Thank you for the reply. Okay I just shut it off, but it looks to me that the kiln sitter was on its way of falling and got jammed. I barely touched the sitter and it fell, so it looks like it did hit cone 5??? But its been at that temp for god knows how long, 9 to 10 hours maybe? Anybody know what will happen to the wares or whats likely to happen. 

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I find my relays stay on towards the top end of my cone 6-7 firings, so no clicking sounds. Firing by colour is surprisingly accurate, and might be your best indicator at the moment of how hot things got. You won't know for sure until you are able to open it.

I know this comes too late, but next time you might want to set your limit timer for an hour longer than your usual firing time. 


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No witness cones-well thats an error for sure.

If the sitter got jambed-did you place a shelve to close to it(things expand in heat)??


You will see when it cools what temp you got to.

Let us know how this turns out.

My guess is it got to hot-lets hole this did not happen.


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13 hours ago, liambesaw said:

If the sitter got stuck it's probably way overfired

Obviously you were coming home after work, and checked on the kiln first thing, but this is a reason a lot of over fired kilns occur, and in the worst case scenario, fires and damage to your kiln/building.

If you dont have a single day off per week where you can fire, try starting the kiln when you get home from work, and wake up when its supposed to go off.

Dont depend on technology to save you, because it will fail, at some point. We all get a little too dependent on the tech to do its job, but we usually pay for it at some point in time.

I hope your pots aren't too over fired, and shelves gunked with runny glazes!Lessons learned!

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If the pic is the inside of your kiln  and is a true colour,that colour says to me that you are  way over cone 5!

Kiln sitters stick. Latch doesnt drop. 

How do you know cone or temp??

Turn itvoff and have a look.

Good luck.

I really find it hard to believe folk turn kilns on and walk away. Out of the house etc.

So much resting on systems which fail .

Good luck.

Please dont walk out on your kiln again.

Dont think insurance company would take a second look.....

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Hey forget the pottery thank goodness nothing worse happened. Some of the other guys here can correct me if I'm wrong but a run away firing for 11 hours is really bad. What if you had gone out to diner or even left town. Not sure at what point continuously firing  kiln starts becoming a real danger but at some point it does and you were going about your day assuming all was well.

One thing we are adding to our studio is a IP Camera. Those are great. I have a $30 one at the gallery and I can be anywhere in the world and simply bring it up on my phone. It will pan around and even works in a pretty dark room.I use it so I can watch the door from my desk as I work.  We have controllers so we can just see the complete message flashing and temp dropping. I assume with yours you would see the glow dissipate from the witness cone peeper if you left the top one out??? 

Edited by Stephen
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Wow... really hoping, Jothamhung, that your kiln and  ware escape serious harm.

I have had firings go wrong over the many years, both with my manual kiln and the digital that replaced it. Fortunately, I have been on hand and been able to take action immediately, saving the loads.

I always set witness cones, with at least one pack viewable from, preferably, the top peep hole. I always peer at the cones sets during the latter part of the firings, making sure everything is on track. This is so I can make adjustments, or shut off the kiln, if necessary.

On my manual kiln, I always set the timer to one hour beyond the expected total firing time.  Always checked and double checked the placement of the cone in the kiln sitter and that I was using the correct cone.

On my digital kiln, I set the program and double check it before starting. Every firing I use a surveillance camera on a tripod set up pointing at the digital controller screen. With an app  on my iPhone I can check in and see how the firing is going, saving me from having to go out to the shop to check the kiln. The camera and app work over my own WiFi system and that is good enough because I never, ever leave to do anything when the kiln is firing.

I always fire my kilns during the overnight hours. Electricity is cheaper during off peak times and the flow is more reliably stable, with less chance of fluctuations that can impact the firings. I can also devote myself fully to the firing, with no distractions, as I am either sleeping, or checking the kiln. 

During my manual kiln firing years, I would set all my alarms in advance, wake up, go out three times during the night to turn the switches and check all is well, and then go right back to bed.

Firing my digital kiln is easier, as whenever I wake up, I reach for my phone and check to see what the current temperature is and that the firing is going as planned. This is great as I don't even have to get out of bed.

All the firings end in the morning. I don't even get dressed most times. Just sit out in the shop and watch the kiln finish firing, sipping coffee, in my pajamas. I got so good at predicting the end of a firing with my manual kiln that I was nearly always present when the weight dropped, shutting off the kiln. Every time, it would snap and I would jump! Every time!

 With the digital, I am nearly always present for when the controller suddenly stops the firing and blinks CPLT, alternating with the current temperature of one of the thermocouples. Because I am there, I can record the exact temperature that the kiln reached at time of shut off.

I always put the last plug into the top peep hole, usually within a minute of finishing firing, so the kiln can cool as slow as possible.

And I keep detailed records of every firing. I have records going back decades.

My respect for what can go wrong is too much for me to not stay on top of things, that's for sure. 

Thanks for being patient reading this long response.

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  • 11 months later...
On 1/25/2019 at 11:12 AM, WoodlandPotter said:

.... Every firing I use a surveillance camera on a tripod set up pointing at the digital controller screen. With an app  on my iPhone I can check in and see how the firing is going, saving me from having to go out to the shop to check the kiln. The camera and app work over my own WiFi system and that is good enough because I never, ever leave to do anything when the kiln is firing.

What kind of camera are you using? I just got a Wyze and can't read the digital readout -- the red numbers are blurry -- but the camera is several feet away from the kiln on a bookcase, not right in front of it. 

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