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Reduction firing in electric kiln


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#1 Claypple

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Posted 14 March 2013 - 10:06 PM

Has anybody had a good experience with firing in Reduction mode using a sagger, e.g. in an electric kiln?
I can imagine majority of you, pros, have a gas kiln for that, but maybe somebody was experimenting and could share it with me/us? Please.
I really like the effect that reduction leaves on the glazes, but I am not planning to buy the gas kiln yet.

#2 Marcia Selsor

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Posted 15 March 2013 - 05:46 AM

I think you are referring more to higher firing with ^6 or 10 glazes but this is interesting work using saggars in electric kilns.
Google Russel Fouts. He has written articles about that for PMI. and he hasn't changed his elements in 20 years.
He has another article in this month's PMI but unrelated.
He uses aluminum foil sag gars and all kilns of resists. His work fired in foil saggars was in the NCECA Biennial in Louisville among others.
here is his website
http://users.skynet.be/russel.fouts/
He lives in Brussels and comes to NCECA.
He is a good friend of mine.

Back you your original question, someone else may have to answer that.

Marcia

#3 neilestrick

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Posted 15 March 2013 - 08:24 AM

What exactly are you hoping to achieve? Iron spots in the clay, or certain glaze effects?

At low fire temps elements last forever, and the effects of reduction on their lifespan is probably minimal. At cone 5 and up you'll never get 20 years out of your elements unless you only fire 4 times a year. But many people have posted here that occasional reduction hasn't really affected their element life.
Neil Estrick
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#4 OffCenter

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Posted 15 March 2013 - 09:12 AM

Has anybody had a good experience with firing in Reduction mode using a sagger, e.g. in an electric kiln?
I can imagine majority of you, pros, have a gas kiln for that, but maybe somebody was experimenting and could share it with me/us? Please.
I really like the effect that reduction leaves on the glazes, but I am not planning to buy the gas kiln yet.


Off and on I experiment with doing reduction in an elect kiln. I have a small reduction kiln but prefer electric reduction because the oxidation atmosphere in an elect kiln is purer, therefore, the contrast between the "oxidized" part of porcelain and the reduced part is greater which makes it possible to get the comet effect so famous from wood firing, and other effects. As a matter of fact, right now I'm firing an elect kiln for some copper reds. I have a nice copper red for the reduction kiln that looks even better when fired in a sagger in the elect kiln. I tried to post pics but I guess because of the pics in my profile gallery I've used up my space and can't post pics here. When I have more time will remove something so I can post pics again. Sometimes I try to get one pot to fire copper red on the bottom feathering out to a copper green on top by firing the bottom half in reduction and top half in oxidation but so far have not been successful. I think that as long as you don't overdo it, firing reduction in an electric kiln doesn't shorten the life of the elements (or if it does, not much).

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#5 OffCenter

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Posted 15 March 2013 - 09:45 AM

I like reduction in elect kilns as experiments and for "special" pots. In other words, I'm NOT trying to get the effects of a reduction firing in an electric kiln, I'm trying to get something better. Firing pots to reduce the body and glaze isn't a good idea in an elect kiln unless you're satisfied with just firing two or three pots at a time. If you want to do reduction firings without building a kiln, your best bet is to find a potter-school-community center that will let you fire in their kiln. The second best thing is to buy an Olympic reduction kiln that is just an elect kiln without the elect parts and with a hole in the lid and burners under it. I've called them "just big hot toys" here before but they're better'n nothing if you want to do reduction firings.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#6 Claypple

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Posted 15 March 2013 - 10:04 AM

1) Thank you Marcia. I am VERY hesitant to use an Aluminum foil for two reasons: not good for environment, cannot be good for the elements in the kiln (isn't it?)
2) Thank you Neil. Ideally I like the effect of wood firing on the glaze. Reduction firing is the closest to it that I could find.
I can see how it can be harmful for the elements if it changes the atmosphere inside of the kiln, but what if I use a completely enclosed vessel and open it only outside of the kiln?
3) Thank you Jim. So, what exactly are you using to create the reduction atmosphere? I was thinking about it and came up with an idea of a "pot in a pot", but then found out it was an old news in the pottery science, and it is called a "saggar".
So, what do you use?[ aluminum? another ceramic vessel?] What is inside? [moths? sugar cube? papers?]


#7 Marcia Selsor

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Posted 15 March 2013 - 10:22 AM

No, the aluminum doesn't melt. He does not fire the sag gars very hot 500 C or 932 F. He has been using the same elements for 20 years.
He uses paper, lipstick crayons etc. as resist to smoke.

The kiln that Electric Cat mentions is another way or you can put metal ITC on new elements and reduce your electric with a bunsen burner.
Check this concept for hybrids in the clayart archives. The ITC protects the elements and the bunsen burner reduces the atmosphere. The eletrcic coils produce the heat.

Marcia

#8 Claypple

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Posted 15 March 2013 - 11:02 AM

No, the aluminum doesn't melt. He does not fire the sag gars very hot 500 C or 932 F. He has been using the same elements for 20 years.
He uses paper, lipstick crayons etc. as resist to smoke.

The kiln that Electric Cat mentions is another way or you can put metal ITC on new elements and reduce your electric with a bunsen burner.
Check this concept for hybrids in the clayart archives. The ITC protects the elements and the bunsen burner reduces the atmosphere. The eletrcic coils produce the heat.

Marcia


Oh, I see. Such a low temperature! Almost looks like a good Kamado grill would make it. I am not kidding. If you modify the process of heating it, the temperature easily goes to 900F.
I think now I have to do some reading/studying on the physics/chemistry of reduction glazing.

#9 Claypple

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Posted 15 March 2013 - 11:11 AM

"No, the aluminum doesn't melt. He does not fire the sag gars very hot 500 C or 932 F"

Marcia is right, it doesn't melt, it pulverizes at 1010F, so if you fire hotter, you get nice little flakes of foil all over your kiln.


Just what we all need! :-)

#10 OffCenter

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Posted 15 March 2013 - 11:15 AM

3) Thank you Jim. So, what exactly are you using to create the reduction atmosphere? I was thinking about it and came up with an idea of a "pot in a pot", but then found out it was an old news in the pottery science, and it is called a "saggar".
So, what do you use?[ aluminum? another ceramic vessel?] What is inside? [moths? sugar cube? papers?]


I've used all sorts of things. Some materials form glazes. (Pile lawn clippings on a pot and you'll get a puddle of white glaze, Some dog foods have copper and sometimes produce flashes of copper. I've got interesting results with brillo pads, deer livers, bamboo, sugar, magnolia leaves, etc.....). For a nice matte black I use coffee grounds (Starbucks gives theirs away). Moths are too hard to catch. Mothballs are too tiny and the chemical kind can kill you. Experiment. Try this for starters: throw a cylinder the size of a wide mug and make a lid for it. No need to make them pretty or have a flange on the lid (just a disk will do) but they do need to be thick. This is a small test sagger. Maybe make several of varying sizes. I usually try for a black pot with white streaks which I do by burying the (unglazed on the outside) pot in coffee grounds up to a little below the lip and I sometimes have a large hole in the sagger on one side and a small hole on opposite to get streak of oxygen. But if you just want to create a reduction atmosphere inside the sagger, make test cylinders small enough to fit inside the saggers (not a tight fit) and put them on top of a clay disk to raise them above the coffee. Fill the bottom of the sagger with coffee (sugar or sawdust work, too, but I like coffee best) but don't let it touch the glazed pot. Put the lid on and fire. You will probably be unhappy with the results because you haven't experimented enough yet to know what you're doing. Now, if you think it is worth the effort, experiment and discover!

When I take down some of the pics in my profile gallery, I will be able to post pics here. I've gotten much better results, but one example you can see in my profile gallery is a tea bowl that won an award in the National Tea Bowl show a few years back.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#11 Claypple

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Posted 15 March 2013 - 11:24 AM


3) Thank you Jim. So, what exactly are you using to create the reduction atmosphere? I was thinking about it and came up with an idea of a "pot in a pot", but then found out it was an old news in the pottery science, and it is called a "saggar".
So, what do you use?[ aluminum? another ceramic vessel?] What is inside? [moths? sugar cube? papers?]


I've used all sorts of things. Some materials form glazes. (Pile lawn clippings on a pot and you'll get a puddle of white glaze, Some dog foods have copper and sometimes produce flashes of copper. I've got interesting results with brillo pads, deer livers, bamboo, sugar, magnolia leaves, etc.....). For a nice matte black I use coffee grounds (Starbucks gives theirs away). Moths are too hard to catch. Mothballs are too tiny and the chemical kind can kill you. Experiment. Try this for starters: throw a cylinder the size of a wide mug and make a lid for it. No need to make them pretty or have a flange on the lid (just a disk will do) but they do need to be thick. This is a small test sagger. Maybe make several of varying sizes. I usually try for a black pot with white streaks which I do by burying the (unglazed on the outside) pot in coffee grounds up to a little below the lip and I sometimes have a large hole in the sagger on one side and a small hole on opposite to get streak of oxygen. But if you just want to create a reduction atmosphere inside the sagger, make test cylinders small enough to fit inside the saggers (not a tight fit) and put them on top of a clay disk to raise them above the coffee. Fill the bottom of the sagger with coffee (sugar or sawdust work, too, but I like coffee best) but don't let it touch the glazed pot. Put the lid on and fire. You will probably be unhappy with the results because you haven't experimented enough yet to know what you're doing. Now, if you think it is worth the effort, experiment and discover!

Jim


WOW!! This is priceless! Sounds like an alchemistry and sorcery combined. I meant it in a good sense.
I started doing pottery for many reasons. One was that I was a collector and could not find what I liked, so I have been still looking for that perfect shape and glaze.
Thank you for these ideas.

#12 OffCenter

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Posted 17 March 2013 - 08:50 AM



3) Thank you Jim. So, what exactly are you using to create the reduction atmosphere? I was thinking about it and came up with an idea of a "pot in a pot", but then found out it was an old news in the pottery science, and it is called a "saggar".
So, what do you use?[ aluminum? another ceramic vessel?] What is inside? [moths? sugar cube? papers?]


I've used all sorts of things. Some materials form glazes. (Pile lawn clippings on a pot and you'll get a puddle of white glaze, Some dog foods have copper and sometimes produce flashes of copper. I've got interesting results with brillo pads, deer livers, bamboo, sugar, magnolia leaves, etc.....). For a nice matte black I use coffee grounds (Starbucks gives theirs away). Moths are too hard to catch. Mothballs are too tiny and the chemical kind can kill you. Experiment. Try this for starters: throw a cylinder the size of a wide mug and make a lid for it. No need to make them pretty or have a flange on the lid (just a disk will do) but they do need to be thick. This is a small test sagger. Maybe make several of varying sizes. I usually try for a black pot with white streaks which I do by burying the (unglazed on the outside) pot in coffee grounds up to a little below the lip and I sometimes have a large hole in the sagger on one side and a small hole on opposite to get streak of oxygen. But if you just want to create a reduction atmosphere inside the sagger, make test cylinders small enough to fit inside the saggers (not a tight fit) and put them on top of a clay disk to raise them above the coffee. Fill the bottom of the sagger with coffee (sugar or sawdust work, too, but I like coffee best) but don't let it touch the glazed pot. Put the lid on and fire. You will probably be unhappy with the results because you haven't experimented enough yet to know what you're doing. Now, if you think it is worth the effort, experiment and discover!

Jim


WOW!! This is priceless! Sounds like an alchemistry and sorcery combined. I meant it in a good sense.
I started doing pottery for many reasons. One was that I was a collector and could not find what I liked, so I have been still looking for that perfect shape and glaze.
Thank you for these ideas.


Claypple,
If your interest in sagger firing is to get reduction firing results, I think a better way to do that is to read up on Steven Hill. (You say you're a beginner, so maybe you're not familiar with him.) Like so many of us who started potting in the '70's (I took a 30-year sabbatical.), he was taught that real potters do cone 10 reduction and became one of the best potters in the country doing cone 10 reduction for a few decades, then he realized that all that stuff about cone 10 reduction was BS. There is nothing superior about cone 10 reduction. Clay fired to cone 10 isn't necessarily stronger, more vitrified or in any way superior to Cone 6 or even earthenware (See lots of posts here about Pinnell's MOR tests.) But most importantly, he discovered that he could get just as good or better glazes firing cone 6 electric as cone 10 reduction. He has written many fine articles about single-firing, spraying glazes, etc. Google them and if it sounds right to you buy the dvd "Surface Techniques of Steven Hill". It's expensive but well-worth the money.

Jim
E pur si muove.

"But it does move," said Galileo under his breath.

#13 Marcia Selsor

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Posted 17 March 2013 - 09:56 AM


"No, the aluminum doesn't melt. He does not fire the sag gars very hot 500 C or 932 F"

Marcia is right, it doesn't melt, it pulverizes at 1010F, so if you fire hotter, you get nice little flakes of foil all over your kiln.


Just what we all need! :-)


this is why it is done in a kiln with controls and pyrometer and not a bbq. Precise temperature is crucial.
Jim's recommendation for Stephen Hill is a good one. He does beautiful work and a good teacher.


Marcia

#14 Claypple

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Posted 17 March 2013 - 11:05 AM

Great, I appreciate advices like that. Jim, I will definitely buy the DVD!
I AM new, and I am learning quickly! (By making mistakes too, Ha!)

#15 Claypple

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Posted 18 March 2013 - 09:50 AM

[/quote]
this is why it is done in a kiln with controls and pyrometer and not a bbq. Precise temperature is crucial.

[/quote]




I think maybe you do not know what Kamado grill is. I guess the word "grill" is quite deceiving here.
I am really amazed by its design. It is an ancient Japanese engineering, and the modern technology made it even more efficient.
Not that I am going to really use it for firing of clay.
(It would still require some modification to see the pyrometric cones and it would require natural gas instead of wood.)



#16 Marcia Selsor

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Posted 18 March 2013 - 12:47 PM

[quote name='Claypple' date='18 March 2013 - 08:50 AM' timestamp='1363618242' post='31161']
[/quote]
this is why it is done in a kiln with controls and pyrometer and not a bbq. Precise temperature is crucial.

[/quote]




I think maybe you do not know what Kamado grill is. I guess the word "grill" is quite deceiving here.
I am really amazed by its design. It is an ancient Japanese engineering, and the modern technology made it even more efficient.
Not that I am going to really use it for firing of clay.
(It would still require some modification to see the pyrometric cones and it would require natural gas instead of wood.)
[/quote]
Pyrometer. I don't know any cone for 932 F.
And soak for 30 minutes at that temperature.It is a type of saggar firing done in an electric kiln. ..as per your original question.

Marcia

#17 Marcia Selsor

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Posted 19 March 2013 - 05:10 PM

Talked to Russel about your Kamado kiln for firing. As long as you control the temperature probably with a pyrometer, you could do it. you don't want the foil to get too hot.
If you read his article you might understand the premise.

Marcia

#18 Claypple

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Posted 19 March 2013 - 05:53 PM

Talked to Russel about your Kamado kiln for firing. As long as you control the temperature probably with a pyrometer, you could do it. you don't want the foil to get too hot.
If you read his article you might understand the premise.

Marcia


Marcia, thank you very much!! Thank you for questioning and thank you for checking. I will definitely read the article, too.
I am intrigued with Steven Hill's way to do the reduction firing, and I am amazed with the physics and chemistry of reduction firing in general.
I'm planning to "play" with it in different kinds of kilns.




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