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Yes the cone did bend but very little and it does have a timer. I didn't realize my husband set the timer for 5 hrs. And honestly I have just gotten this kiln and I am not to sure on how to work it nor how long the firing process will take for the greenware to fire to cone 04. Is been a long time since I had a kiln in the early 70"s. And I don't recall how I did it back then! And haven"t found much on the internet that tells you how long it takes. But in my search I found this site.

I did restart it at 12:39 pm with the cone in the sitter and a wittiness cone and I set the timer to 17 hours. Is this enough time? And thank you for your reply

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If 04 bent at all and assuming there is no special reason for going to 04, such as solving pinhole problems with glazes, your pots have been fired high enough for a bisque and re-firing them will just be a waste of time and electricity. 04 is a little on the high side for bisque firing, anyway. The only clay I bisque over 012 is Lizella Red which needs to be bisqued higher to avoid pinholes in the glaze.

 

Jim

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OK, more info helps. since it is an electric kiln there is a manufacturers name somewhere on it. if it is an older one, you can find out the firing directions that particular company gives out to owners by contacting them directly. it is always better to talk to the people who know the most. find their phone number on the internet, but TALK to someone in their technical section on a phone. tell them ALL the information you find printed on the kiln and measure it's depth and width, inside, just in case you cannot find much. they should be willing to send you written info once you have talked to them. maybe there is a small cost but find out.

 

yes, these forums are great but we all have different experiences. i have never had a timer on a kiln sitter until one i was given a couple of years ago. it still makes no sense to me but i have it written down in that studio and refer to it when i fire that kiln. that is why i suggested the possibility that the timer was set wrong. i've done that. once was enough.

 

is the "cone" in your sitter a pyrometric bar with four sides all the same or is it an actual cone that tapers? something else to consider.

 

have fun with your kiln and happy potting.

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My kiln fires to 04 in 6 hours, (I know this from experience) so I set my timer for 7 hours, with a kiln sitter and cones on two shelves. Your kiln may be different == but 17 hours is likely WAY too long. But no harm as along as you keep watch, and your kiln sitter works. If your sitter doesn't turn the kiln off after 6 hours, turn it off yourself and see where the cones are inside the kiln. When you have a kiln that's new to you, you have to expect to experiment a little. Of course, depending on how you load the kiln, there will be a lot of trial and error. That's why it's important your kiln sitter is working properly.

I agree though that 04 is a bit high for bisque. I try to fire to 05 for my bisque and glaze to cone 6 (for stoneware, that is!) You didn't mention what kind of clay you are using -- earthenware or stoneware? I fire to 04 bisque, and 05 for glaze on earthenware. But you should ask whoever sold you the clay what cone to fire to, as clay bodies are all a little different.

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The most informative 'Operating Manuals' I have ever encountered comes from Skutt Kilns.

Measure your kiln if you don't already know the dimensions. Find the Skutt Kiln that comes close in dimensions and maximum firing temperature and you will find a lot of information on how to fire your kiln. http://www.skutt.com/pdf/op_manual/KS_manual/KS_OperatingManual_2002.pdf

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  • 6 years later...
On 11/16/2019 at 8:43 AM, vpottery said:

well have an older kiln that I have to turn manually--ie, low, medium , high.  my kiln shut off without the cone bending properally  my question is would it hurt to re-bisque  or take a chance and glaze?

To answer your question, it should not hurt.

Normal  bisque schedules are 10 - 12 hours to cone 05/04. Some clays are just fine with faster schedules but the purpose of the bisque is to remove all organics, chemically combined water and sinter the body to make ready for handling and glaze.
 

The time your clay is at a temperature allows for complete burnout which is why many common schedules go in the 200 degree per hour time and last as long as they do. The sintered product has not melted so refire should not present any issue.
 

Glaze schedules on the other hand generally last 5 - 9 hours with speeds in the 400 degree per hour range.

A typical bisque schedule below. Folks with manual kilns often turn on low for several hours, then medium, then high at the end to try and slowly ramp up to their bisque temperature over 10 to 12 hours.

 

Edited by Bill Kielb
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