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Minimum firing temps


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#1 Shereen

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Posted 05 May 2013 - 04:50 AM

Hello,
I took ceramic classes at Berkeley years ago and loved it, however my work is now all glass. I have three "glass kilns' and they don't recommend (I don't know why) that you go past 1900 ...err even 1800 that often. When I have molten glass coming put the bottom of the kiln it's only at 1720.

My question, I would love to work with some clay and I did buy some low fire clay last year but got busy with commissions. Is there any clay that can be fired in glass kilns? Going no higher than 1900? I would Love to work with porcelain..any chance?

Thank you VERY much.
Shereen

#2 Frederik-W

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Posted 05 May 2013 - 06:14 AM

1800 F (980 C) is just good enough for earthenware, I'm afraid.
So you can try earthenware clays, e.g. terracotta.
Commercial earthenware glazes are often designed for around 1980 F but I'm sure you will be OK with some earthenware glazes, or mix your own.
If you "soak" at top temperature, e.g. once you reach top temperature let it rest there for 15mins or so, it will be the equivalent heat-work of taking it to a higher temperature.

If you fire art/display type objects like sculptures etc, i.e. not utilitarian objects like cooking ware, then often you do not really need to fire so high.

We can learn a lot from e.g. people in Africa, who make beautiful and functional ware at low firing temperatures with wood and pit-firing.

Low firing should be encouraged. It saves a lot on electricity. Less greenhouse-gas emissions. Better for the planet.


#3 weeble

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Posted 05 May 2013 - 06:16 AM

Your glass kiln is optimized for a lower temperature, which means the elements (and other bits and bobs in the kiln!) are probably thinner and will probably burn out pretty quickly firing higher than recommended. You could fire clay at that temperature, but unless you find a body formulated to mature at that temperature, your clay will be underfired. You're talking somewhere around cone 08 or 07, depending on how fast you fire and soak time. Depending on what you want to do, that might work for you, but probably best for decorative work. It probably won't be vitrified. Porcelain is generally a high fire clay requiring temperatures well above what you can do with that kiln, the mid-range porcelain I've used is designed for cone 5, which is somewhere around 2100-2200, so really, no chance porcelain will be a good choice for you.

If you really want to do functional work in clay, see if you can find a group in your area that has a kiln and will fire work for you. I work with a group at the local art center, you might find one checking with the area colleges or art groups.
Maryjane Carlson

Whistling Fish Pottery

#4 Shereen

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Posted 06 May 2013 - 12:40 AM

Thank you very much for your help! I'll check for a local place who'll fire fire for me. I really appreciate your help. With glass, you can fire a tad lower and soak a little longer and it's usussly better in the long run. I was hoping this might be the case.

Thanks again!
Shereen

#5 Mark C.

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Posted 06 May 2013 - 01:32 AM

Electric kilns are cheap and you can also pick them up second hand.
As your studio is wired for electrics consider a ceramic kiln as another option.
That way you will learn the whole process which you will not usually taking classes alone.
As well as controlling all outcomes.
Mark
Mark Cortright
www.liscomhillpottery.com




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