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Stopping the bisque firing early


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#1 Nelly

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Posted 29 September 2012 - 03:31 PM

Dear All,

Last night I started a bisque load of work. I candled 6 hours at 200 degree with the peeps open and the lid slightly ajar. I closed the lid this morning as the temperature started to climb.

The kiln started is in slow bisque firing mode. I know that cone 04 self supporting cones are roughly done at 1945 degrees but I decided today to turn if off early. I pushed stop at 1850. All peep holes remained closed except the top one.

What will happen???

Here are my guesses?

1. Nothing

2. The long candling would or should have done a good job getting the last vestiges of water out of the pieces. Thus, I am hoping I am okay and will have no explosions.

3. Some glazes may be affected possibly by pin holing. Having said that so many factors are involved in the avoiding of pinholing it will be hard to tell if it is the effect of stopping the kiln early.

A friend of mine told me once if you are leaving the studio with your kiln on for a significant length of time that turning it off is usually the best policy if you have not planned for an interruption. I had to leave for a few hours. While I knew it was likely to go off at this time, I didn't want to chance anything.

Does anyone have any insight into if or how this will affect my work. It is stone ware clay with some plainsmen clay marbelling on large platters.

Thank you in advance.

Nancy

#2 Chris Campbell

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Posted 29 September 2012 - 04:12 PM

The answer is .... 1- Nothing

A huge number of potters bisque to 05 - 06 range which is just where you were. You might even get better results ??

Was your work really wet? I wondered since you candled so long.

As to the leaving the kiln while it is firing part ... I think it is only critical to be there at the end of the firing. We all have to leave our kilns unattended during the bulk of the firing, or we would not get anything else done! :D

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#3 Nelly

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Posted 29 September 2012 - 04:21 PM

The answer is .... 1- Nothing

A huge number of potters bisque to 05 - 06 range which is just where you were. You might even get better results ??

Was your work really wet? I wondered since you candled so long.


Dear Chris,

Thank you for getting back to me. I candled a long time because I have noticed with the addition of heavily iron laden Plainsmen clay with Tuckers Mid Smooth Stone that sometimes they are happy together as a blend and other times they explode. It only happens for me with the Plainsmen Clay.

The mid-smooth stone is a workhorse clay body. You can do anything to this clay. Build, throw, clean up edges when it is bone dry etc and nothing affects it.

The Plainsman on the other hand is heavy with iron. It is almost greasy. But the color is worth the pain in working with this clay.

This is the reason I candled for a long time. I always do the cheek test. They were both still a little cool but my studio has been on the cold side due to our weather here. I have also had a recent explosion in the kiln with this combination. But then again, other times it works like a dream. So, I don't know.

I put this extra color in the body to create depth with some different glazes. It sort of mixes up the effect on pieces where you sort of slop throw the glaze and/or oxides I use.

Anyway, I am glad I made a good call and decided to turn it off in my absence. And yes, you never know, it may even be better?? I will keep you posted.

Check out Plainsman clay if you have a moment. It is the darkest smooth clay body that I use. I will look it up and send you a link.

Nelly

#4 Nelly

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Posted 29 September 2012 - 04:40 PM


The answer is .... 1- Nothing

A huge number of potters bisque to 05 - 06 range which is just where you were. You might even get better results ??

Was your work really wet? I wondered since you candled so long.


Dear Chris,

Thank you for getting back to me. I candled a long time because I have noticed with the addition of heavily iron laden Plainsmen clay with Tuckers Mid Smooth Stone that sometimes they are happy together as a blend and other times they explode. It only happens for me with the Plainsmen Clay.

The mid-smooth stone is a workhorse clay body. You can do anything to this clay. Build, throw, clean up edges when it is bone dry etc and nothing affects it.

The Plainsman on the other hand is heavy with iron. It is almost greasy. But the color is worth the pain in working with this clay.

This is the reason I candled for a long time. I always do the cheek test. They were both still a little cool but my studio has been on the cold side due to our weather here. I have also had a recent explosion in the kiln with this combination. But then again, other times it works like a dream. So, I don't know.

I put this extra color in the body to create depth with some different glazes. It sort of mixes up the effect on pieces where you sort of slop throw the glaze and/or oxides I use.

Anyway, I am glad I made a good call and decided to turn it off in my absence. And yes, you never know, it may even be better?? I will keep you posted.

Check out Plainsman clay if you have a moment. It is the darkest smooth clay body that I use. I will look it up and send you a link.

Nelly


Dear Chris,

Here is the link:

http://plainsmanclay...m/data/M390.HTM

While it is made for use in schools, I can tell you it is not easy to work with. It requires careful attention to water and attempts to dry rapidly. In is the type of clay you must almost get intimate with in your knowledge of how it performs.

I love it for it's color. It strikes a happy medium for me in allowing me to mix different stone ware colors. I started using it because the studio where I used to work would not allow terra cotta or low fire ware. Thus, this seemed a close enough fit for my purposes. I can still decorate with slips and get great results.

But it is one greasy clay body. I would call it the "trickiest" clay I have ever thrown or worked with in my time potting. But then again, I have never really worked in porcelain and have been told this is a tricky clay to use as well. This would make another good forum topic--what is the trickiest clay body you have ever worked with in your experience.

Thank you Chris for the answer to my question.

I will keep you posted as to the results.

Nelly

#5 Mark C.

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Posted 29 September 2012 - 07:36 PM

Nothing is the right answer-Do I get a door prize?
Mark
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#6 Nelly

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Posted 30 September 2012 - 10:19 AM

Nothing is the right answer-Do I get a door prize?
Mark


Dear All,

The correct answer was indeed "nothing." I just unloaded the kiln. The platters are pristine. Strong white/brown contrast with absolutely no (zippidy doo dah) cracks, warping or damage. I would say the key for me in this new kiln and with my old combination of marbling is either a really, really long air dry period or slow and even candling...this was my conclusion from this firing.

As for turning the kiln off prematurely, I will have to wait to see the final impact this will have on the glaze firing.

Thank you one and all and if I was closer, I would indeed give you both prizes for the correct answer!!!

Nelly

#7 Chris Campbell

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Posted 30 September 2012 - 11:10 AM

You have hit the nail on the head for working with clay bodies and choosing one over another and the value of 'learning' the personality of a clay body you like.
Whatever you base your choice on ... be it color, texture, flexibility ... or the way it accepts texture or carving ... the way it toasts on the edges or cleans up well, feels great after firing ... you, the potter, will have to learn to accept the downsides, work around the problems ... live with the fact that there are issues. The rewards of doing this pays off over the years as it becomes a good friend.
There definitely is no one clay that makes everyone happy.

Chris Campbell
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#8 Mark C.

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Posted 30 September 2012 - 11:59 AM

Nelly
I fire a car kiln about each week here and do so by eye with no cones just a digital pyro. Often If I have to leave early I shut it down within about 100 degrees -the only thing one notices is the bisque can absorb a tad more glaze.
Mark
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www.liscomhillpottery.com

#9 Nelly

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Posted 30 September 2012 - 02:22 PM

Nelly
I fire a car kiln about each week here and do so by eye with no cones just a digital pyro. Often If I have to leave early I shut it down within about 100 degrees -the only thing one notices is the bisque can absorb a tad more glaze.
Mark



Thank you for your reply Mark. Can I compensate for this extra absorption by say wetting the piece a little more than with the damp sponge (i.e., a quick dunk in a bucket) or water my glaze down a bit more when I apply??

I guess it is a trial and error thing. I am getting ready for a holiday show in December so I still have time to experiment.


Thank you all again for all your comments.

Nelly

#10 Mark C.

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Posted 30 September 2012 - 02:39 PM

I would not worry about it and glaze normally
Mark
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#11 SmartsyArtsy

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Posted 30 September 2012 - 07:24 PM

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