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dofan

Cannot See Witness Cones

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I have a Skutt electric kiln that I purchased from another potter.  I have such a hard time seeing the cones during firing. It is just too bright and I cannot make out the shape.

 

The kiln is reading low as the witness cones are coming out with only the first (lowest) cone bent. We are trying to fire at cone 6 and we are consistently getting a cone reading of 5 or maybe 5.5 when computer is set to cone six.

 

Does anyone else have trouble with seeing the cones ... if so, what have you done to correct the issue?

 

I am just starting out and have been using the potters choice high fire glazes. they are rated for cone 5-6.  I am afraid to set my kiln to 7 to accommodate for the lack of firing temp until I can see the cones and have better idea of what is actually happening inside the kiln.

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I use a high intensity LED flashlight to view the cones. (TechLite lumen master) You can Google the name to get more info. I also made a video showing the results with the flashlight. In the video cone 9 is on the left starting to bend.

I posted this info once before but no one responded. I have a friend that also uses the TechLite.

Aloha,

http://www.flickr.com/photos/67879015@N05/6698264613

dofan and justanassembler like this

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The kiln is reading low as the witness cones are coming out with only the first (lowest) cone bent. We are trying to fire at cone 6 and we are consistently getting a cone reading of 5 or maybe 5.5 when computer is set to cone six.

What is stopping you from setting your computer to go to cone 7? Or maybe even ~7.5 and see what happens?

I have used cones only few times (anagama and my gas kiln) and you are right, they are not easy to see. Get yourself a pair of gas welding goggles as recommended before. If I recall, cones needed little bit space so there is nothing immediately behind them. Make sure you can see them well from the peep hole before you fire up the kiln. Too close to the peep hole will not help you to see them better.

dofan likes this

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I too had that problem, so I did lots of Googling, and this is what I now have printed out and stuck in the front of my firing book, just in case I forget.

 

1) Place the cones 8†- 12†away from a peephole. Positioning them closer makes them difficult to see.

 

2) Have enough space around the cones to keep them from touching a piece of ware when they bend.

 

3) Position cones so that when viewed from the peephole, they are silhouetted by an element on the opposite kiln wall. (Keep cones at least 2†from an element.) The element that silhouettes the cones should be level with the lower part of the cone. If the element is in line with the upper part of the cone, you won’t be able to see the cone when it bends.

 

4) If you use the three-cone system, always have the higher temperature cone on the same side in every firing. Otherwise you can lose track of which cone is which.

 

5) Wear firing safety glasses when viewing the cones through the peephole. See your dealer if in doubt about which cone number to use with each clay and glaze.

 

I think the best/most/all of that info came from Arnold Howard  of Paragon Industries, Inc.

 

 

It really works for me, despite the position of the peep hole and the twisting/kneeling/neck bending that I have to do.  I make sure the kneeler/gloves/welding glasses are all set up ready to use, especially useful in the early morning inthe middle of winter!!

Celia UK and dofan like this

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Mart, In answer to your question, I guess I am a bit afraid of overfiring the glaze. (though it seems unlikely in light of the readings we are getting. I wonder if the cold weather could be a factor in the readings?  I am going to get some welders goggles and set the kiln higher (cone 7) so I can monitor the cones while firing and get an accurate cone 6

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I use a high intensity LED flashlight to view the cones. (TechLite lumen master) You can Google the name to get more info. I also made a video showing the results with the flashlight. In the video cone 9 is on the left starting to bend.

I posted this info once before but no one responded. I have a friend that also uses the TechLite.

Aloha,

http://www.flickr.com/photos/67879015@N05/6698264613

I tried this and it works really well but I still think eye protection is needed.

Marcia

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Are you familiar with your kiln and controller? 

 

When you say computer I am assuming you mean an electronic controller. What are you going to do once you can see the witness cones better? Override and let it continue firing until you see 6 bend all the way? And then what? Because of the cone readings from past firings you already know it needs to be adjusted. Is there a cooling schedule or does it just turn off at a particular temp  and cool naturally? Is this what you want? Is the kiln vented?

 

Does it have zone control? Cone 6 has a 100 degree top temp variance depending on the ramp speed and if you add a 15-20 minute hold at the top temp that will push a lower cone out about plus 1 with heat work. I would suggest putting cones on each shelf to determine what cone that shelf is hitting. If it has zone control then the kiln should even out firing temp on each element and this will help from shelf to shelf, if not then you will have to adjust the firing schedule and top temp until you are hitting the cone you want overall. Once you are familiar with any known differences you can load accordingly once you know your glazes and how they act in your world.

 

There will be differences from shelf to shelf (zone control will help but not eliminate and shelves move up and down) and from load to load depending on how you load it. Hopefully the kiln will be somewhat consistent from load to load. Ours fires a little hot on the top shelf (and we have zone control) and when it nails 6 on middle the bottom is a little lower. You can use the firing schedule to adjust where you want and you will understand what is going on as you move forward. This will be empowering for you when you need to make adjustments to get what you want out of your glazes.

 

What you are firing will/should determine how things are set up and if you just rely on setting the controller to 6, 7 or whatever you are never going to control what your getting and just going to move forward using the process of elimination (chunking anything that doesn't look nice when you open the kiln).

 

(If you're saying computer did not mean an electronic controller then please ignore my post :-)

 

Good luck!

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A tick I learned that really works if your cones are close to the peep hole.  Get a short length of  rubber tubing and blow into the peep hole while you are looking. The cones cool just enough to be seen... be careful no to get too close or the tubing will melt.

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A few trick are set up a solid backstop behind cones so they stand out at temp.

Also just blow into the hole when looking -My reduction kiln is harder as flames leap out-electrics are so mellow this is easy to do.

Use a wielding glass for eye protection-this also will help-you could also try a laser pointer?

Most folks new to this soon adapt to seeing better with cones its just a learning curve.Try a few of the posted ideas and they will help.

Mark

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