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#1 Dawn~

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Posted 10 June 2013 - 11:59 PM

I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent .

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~

#2 Mark C.

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Posted 11 June 2013 - 05:55 AM

I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent . You will need to calabrate the sitter-follow the manual and the witness cones should be down as well-use the pyro as a guide, Cones only go bad if the get wet. I have has some for 39 years abd they still work fine,
Mark

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~




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www.liscomhillpottery.com

#3 Pres

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Posted 11 June 2013 - 06:32 AM

I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent .

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~


Cones are a one time deal. You use a new set of cones for every firing. They measure the amount of heat work in the kiln, so you could be a little under or a little over temp, but the cone bends when a certain amount of heat work is completed. Lower temp will take longer to bend the cone, higher temp the inverse.

The sentence: . .. .should we take extra care to celebrate the kiln. . . has me confused. What do you mean by that? Do you have any shelves in this kiln? If you use shelves you would want to kiln wash the top side of the shelf. You should also vacuum out the kiln every few firings being careful around element grooves.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#4 Claypple

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Posted 11 June 2013 - 07:19 AM

Did you mean "calibrate"?
If you did mean "celebrate", then most of people on this forum do it with beer.

#5 Pres

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Posted 11 June 2013 - 07:56 AM

Did you mean "calibrate"?
If you did mean "celebrate", then most of people on this forum do it with beer.


Not I, diabetes T2, pass the water!

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#6 MichaelP

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Posted 11 June 2013 - 08:36 AM

Dawn,

Were you witness cones approximately at the same level above the floor the Kiln Sitter cone was? Were they blocked? Did you use self supported witness cones? If not, were they angled correctly? Is your Kiln Sitter adjusted correctly (read its manual)?

And, of course, you know that the cones are not designed to melt: they bend when their Cone parameters are met. If a cone is melted, it means you were well beyond its Cone #. It would be interesting to see how much your witness cone was bent. But, in any case, I think you were close enough to your target point in terms of Cone#.

Actually, the funny thing is that the smaller cones react quicker BY DESIGN. Why Orton uses the came composition for small and larger cones remains a mystery to me.

As for the pyrometer, it's not going to help you much beyond feeding your curiosity. The Cone designation is not based on the temperature only, but on its rate of increase. In this respect, the pyrometric cones are more informative.

P.S. I've never dealt with earthenware, so I don't know if your 6 hours of bisque firing sounds right. Arguably, stoneware requires a more prolonged cycle to dry the ware and then get rid of organic impurities reliably. The kiln itself is able to get to the higher cone of stoneware firing much quicker, but an artificial delay is introduced to slow the things down.

#7 Bob Coyle

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Posted 11 June 2013 - 10:31 AM

I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent .

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~


You cannot trust a new kiln to have an accurate kiln setter shutoff. You need to calibrate it.

What I usually do when I break in a new kiln is set in a bunch of test tiles with the glazes I use and fire the kiln at whatever the default is recommended for the low-med-hi settings. I place two sets of the triangular witness cones( one a cone lower than what you want, one cone at the temperature you want and one cone higher) in the kiln. Put one set on the low shelf and one set on the high shelf. make sure they are in front of the peep holes and at least three inches back from the elements.

Put a pyrometric bar of the correct cone in the kiln sitter and fire the kiln till the correct witness cone on the high shelf just starts to bend. Now you have to look at the kiln sitter and see whether the the weighted arm is starting to descend. The bar should be starting to soften up at this point. You will need to keep it from shutting down the kiln till the correct witness cone has bent over at least half way. This is done by adjusting the setter with a screw driver.

Keep looking through the peep holes at the cones. Once the witness cone has bent to the right position, adjust the sitter weight so that is just clears the metal holder and flops down and shuts off the kiln. The cones can bend over pretty quickly towards the end so check ofter once you see that the cone lower than the one you want is bent over completely.

If your glazes truly mature at the cone temperature you want, then they should look fine when you open the kiln. Once the kiln sitter is adjusted to fall at the correct cone, you should be able to reproduce your ramp for some time. Remember though, There will always be variations depending on how crowded the kiln is and how many firings you have on the elements and kiln setter.

I bought a used kiln and found out I needed to use a pyrometric bar that was one cone higher that I wanted. This is because the kiln sitter shut off depends on the weight of the metal rod that sits on the bar. If it is heavier than it should be, it will push the bar down too quickly. The witness cones inside the kiln do not have this problem.

You will probably find that the cones at the top bend before the ones at the bottom. My kiln shows about a half cone difference but most glazes will not show too much effect. If they do you may need to be selective in your placement or re-formulate them to be less sensitive.

#8 LauraAnna

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Posted 11 June 2013 - 11:52 AM

All great advice - this helped me as well, thank you.

Any time a piece of mine comes out in close proximity to the shape it went in, I celebrate the kiln! YAAAYYY Kiln! Do a little ceremonial dance around it.... Oh-EEE-Oh....EEEE-OHHH

#9 Pres

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Posted 11 June 2013 - 12:21 PM

All great advice - this helped me as well, thank you.

Any time a piece of mine comes out in close proximity to the shape it went in, I celebrate the kiln! YAAAYYY Kiln! Do a little ceremonial dance around it.... Oh-EEE-Oh....EEEE-OHHH


Opening a kiln is like Christmas morning, you hope you get something, you put out all the hints, jumped through the hoops, were a good kid, but in the end its all a surprise! With firing, like Christmas. . . .NO PEEKING!

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#10 jrgpots

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Posted 11 June 2013 - 04:47 PM


Did you mean "calibrate"?
If you did mean "celebrate", then most of people on this forum do it with beer.


Not I, diabetes T2, pass the water!



You can't celbrate with helium baloons either....memmories of the Hindenburg disaster.

Jed

#11 weeble

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Posted 11 June 2013 - 05:57 PM

Lol the Hindenburg was hydrogen, MUCH more flamable than helium. However, mylar and heat..... mmmmm, not too great. Not very dramatic, they just go flat fast. Some brainiac at the local art center thought storing balloons in the kiln room temporarily was a good idea.....




They don't do things like that anymore without running it by me... The balloons might mot have exploded, but there WAS some exploding done!
Maryjane Carlson

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#12 Dawn~

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Posted 11 June 2013 - 10:16 PM


I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent .

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~


Cones are a one time deal. You use a new set of cones for every firing. They measure the amount of heat work in the kiln, so you could be a little under or a little over temp, but the cone bends when a certain amount of heat work is completed. Lower temp will take longer to bend the cone, higher temp the inverse.

The sentence: . .. .should we take extra care to celebrate the kiln. . . has me confused. What do you mean by that? Do you have any shelves in this kiln? If you use shelves you would want to kiln wash the top side of the shelf. You should also vacuum out the kiln every few firings being careful around element grooves.




Yes I meant calibrate darn spell check, and when I said the cone did not melt I meant bend.. (I remind you I'm new at this.) I do understand the difference of the witness cones.. And yes it was like Christmas day when we opened the kiln... nothing broke yahoo! Thanks everyone for all the great advice.. and Humor of course...

#13 Nancy S.

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Posted 15 June 2013 - 09:07 PM



I finally got my old KS818 kiln installed, ready to fire away. I am a new potter, I used earthenwear cone 06 clay . Filled the kiln with green wear, we fired for 2 hours on low, 2 hours on medium 2 hrs 15 min on high it appears to be fine except the bar cone in the KS was melted correctly and shut off the kiln. The witness cone never melted hardly bent .

My question is how do you know if the pottery has been fired correctly? We plan to glaze and refire should we take extra care to celebrate the kiln? Any suggestions are welcome . We also plan on installing a pyrometer to help measure temp. Do cones go bad? Should we buy more I got all these from the person I bought the kiln from .

Thanks again dawn~


Cones are a one time deal. You use a new set of cones for every firing. They measure the amount of heat work in the kiln, so you could be a little under or a little over temp, but the cone bends when a certain amount of heat work is completed. Lower temp will take longer to bend the cone, higher temp the inverse.

The sentence: . .. .should we take extra care to celebrate the kiln. . . has me confused. What do you mean by that? Do you have any shelves in this kiln? If you use shelves you would want to kiln wash the top side of the shelf. You should also vacuum out the kiln every few firings being careful around element grooves.




Yes I meant calibrate darn spell check, and when I said the cone did not melt I meant bend.. (I remind you I'm new at this.) I do understand the difference of the witness cones.. And yes it was like Christmas day when we opened the kiln... nothing broke yahoo! Thanks everyone for all the great advice.. and Humor of course...


Did you use a pyrometric bar or a small cone in the kiln sitter? And what size (large or small) did you use as a witness cone?

The small cones and pyrometric bars are made for kiln sitters, but NOT for use as witness cones. They're designed to melt at a higher level because they're closer to the elements. For witness cones, you need to use the large or self-supporting cones, and many potters - until they "know" their kiln better - will make and use "cone packs" with cones that are also +1 and -1 (called "guard" and "guide" cones). So for a ^06 firing, you'd use ^05, ^06, and ^07 witness cones (plus the ^06 cone in the sitter). This way, you can get a better idea of whether your kiln is reaching the right temperature - and if it's off, by how much. Another thing that you can do is place several cone packs in different areas around your kiln. Some areas may be cooler than others, especially if the elements are old or if it's near an open peephole. Sometimes it's not enough to be the next cone down (or up), but that's why the guard and guide cones are important! This way, you *know* whether your kiln is really off. And if you use small cones in the sitter, be aware of how far off center you position them. That will make a difference in your firing.

As to whether cones go bad -- no, they don't.

Here is a PDF I found that explains cones pretty well.
http://jenkenkilns.c...ones_firing.pdf

Good luck!!




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