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Saggar Firing


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#1 wayver138

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Posted 21 April 2013 - 08:36 PM

Hello all,



I am wanting to experiment with saggar firing in an electric kiln (cone 6). I have been reading a lot of the threads about this and have several ideas to test but still have one question.. I know typically saggar firing is left for decorative pieces but I am wanting to take functional wares with a liner glaze and put them in the saggar to get more interesting surfaces. Since it would be fired to vitrification and has a liner glaze, it would be food safe but what about washing the pots? Would frequent use and washing eventually disrupt the surface? Would certain materials be better for functional saggar firing?

I know there is probably many answers but just wanted to hear some opinions.


Thank you for any advice or direction!

#2 Marcia Selsor

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Posted 21 April 2013 - 08:50 PM

how are you firing to vitrification would be my first question to you?
Marcia

#3 wayver138

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Posted 21 April 2013 - 09:06 PM

Could I not reach temperature inside the saggar? I'm sorry, I'm obviously ignorant on this subject. I've been reading articles on saggars in an electric kiln but have not really seen this subject addressed, more so they seem to be on types of organic materials, etc.

#4 Marcia Selsor

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Posted 21 April 2013 - 09:13 PM

that is because the premise of the saggar firing for decorative purposes is for the clay to absorb carbons from organic material as well as salts, ans metal oxide fumes into a porous body...not vitrified.

SAGGAR firing At cone 6 is usually done in coal kiln using saggar to protect the pieces from coal clinkers.
So your idea has confused me as to what yor ultimate goal is.

Marcia

#5 wayver138

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Posted 21 April 2013 - 09:20 PM

Okay, thank you for the clarification. My original understanding was that some organic materials could still leave an imprint, for lack of a better word, after vitrification. Well, at any rate, I will still experiment on some vases.

#6 Marcia Selsor

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Posted 21 April 2013 - 09:27 PM

Think that is true. It think Jim does this with coffee grounds. I am not sure if he does it in gas or electric.
I hope he will join in and contribute his experience s in doing this. When I see saggar firing, I instantly think of low fore with terra sigilatta.

Marcia

#7 wayver138

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Posted 21 April 2013 - 09:30 PM

Is there another process that I could use unglazed exteriors of functional pots to achieve more interesting surfaces in an electric kiln? I am very interested in using a variety of organic materials to get more spontaneous marks and the like but I only have access to an electric kiln at the moment. My mind isn't really set on the idea of using a saggar, that was just the method that, at first, made most sense to me.

#8 wayver138

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Posted 21 April 2013 - 09:37 PM

Think that is true. It think Jim does this with coffee grounds. I am not sure if he does it in gas or electric.
I hope he will join in and contribute his experience s in doing this. When I see saggar firing, I instantly think of low fore with terra sigilatta.

Marcia




I will be on the look out for his post :)src="http://ceramicartsda...ult/smile.gif">

Coffee grounds was one thing I was interested in using..we go through a lot of it and the coffee shop at school will give it away. Also, I have seen pots with a real nice matte black that used grounds.

#9 Pompots

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Posted 22 April 2013 - 01:56 AM

Is there another process that I could use unglazed exteriors of functional pots to achieve more interesting surfaces in an electric kiln? I am very interested in using a variety of organic materials to get more spontaneous marks and the like but I only have access to an electric kiln at the moment. My mind isn't really set on the idea of using a saggar, that was just the method that, at first, made most sense to me.


You might want to test some oxides on the outside, glaze line the inside and left the outside unglazed and painted with all kinds of oxides
you can make designs, sponge, brush, spray, stamp, anything with oxides and take it all the way to cone 6.

#10 Marcia Selsor

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Posted 22 April 2013 - 07:16 AM

I had a student smoke fired a large piece 24" or so, in a barrel AFTER it was fired to ^6. The bare clay did pick up some coloration from copper etc. he had added to the sawdust.

Marcia

#11 JBaymore

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Posted 22 April 2013 - 07:39 AM

I started teaching a course on high temperature saggar firing back in the 70's at MassArt. Been doing it a bit since. Sometimes even in my noborigama. You CAN do cone 9-10 saggar work with various materials in the saggars. The clay does vitrify. But you have to take into account the thermal lag inside the saggar.... a long hold at the top temp is necessaary.

I don't expect cone six would be as effective.... but you could try.

The outgassing is going to kill your elements faster than they normally would deteriorate. Saggars are not perfectly "sealed" even if you think they are.

best,

...................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#12 OffCenter

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Posted 22 April 2013 - 09:21 AM

I sometimes experiment with saggar firing in electric kilns. I have a small gas kiln but prefer using an electric kiln because you have the nice clean oxidation atmosphere in an elec kiln and can therefore use saggers to control the oxygen getting to the pot. For example, you can take a lidded saggar and put a large hole on one side and a small hole of the opposite side, put a pot in it and fill with coffee grounds and with a lot of luck get a very nice comet effect because most of the pot will be solid matte black except where the oxygen came in through the big hole. Most glazes will be ruined by the heavy reduction in a closed sagger but there's no need to close it except to get solid black or comets. Just use a shallow sagger and put the pot halfway in the coffee, sawdust, grass, dog food (some dog foods have enough copper to be interesting), deer livers, dead cats, whatever so that the bottom will be black then shaded to gray then white (if using porcelain) and the liner glaze will be fine. I've even gotten copper reds in an elect kiln using saggers.

Saggers don't affect vitrification in any way. If your clay is mature at cone 6 on a shelf in the kiln, it will be just as mature in a sagger.

The elements in one of my electrics are all past due for wearing out by normal firings, but (knock on wood) even with all the sagger firing I do they are still working. Who knows, maybe it does the elements more good than harm, but I doubt that. My guess is that "reasonable" sagger firing has no or very little affect on the life of the elements. Now, what I mean by reasonable-- I mean that in a 10cf elect kiln I might have three-fourths of the kiln full of normal glaze ware and only about 1/4 with saggers. Otherwise, you simply have too much smoke. My kilns are in a shed outside with tarp walls that can be rolled up all around and smoke is not a problem. If your kiln is inside it should be well-vented.

Search for other threads but here is one. Lots of info here: http://ceramicartsda...__fromsearch__1
E pur si muove.

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

#13 wayver138

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Posted 22 April 2013 - 01:45 PM

I really appreciate all of the information!

Offcenter- thank you for the detailed response, you covered most of my questions that I have been going over in head-specifically about smoke. I'm really happy to hear that you've had success with it.


I think I will start off with coffee grounds and test a few saggars with differing amounts of ventilation to see what kind of results I can get.

#14 JBaymore

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Posted 22 April 2013 - 02:20 PM

Other things that work well at cone 9-10 include egg shells, chicken bones, seashells, seaweed, blocks of pine wood, charcoal briquettes, hardwood charcoal (gormet barbecue stuff), a SMALL amount of salt, and so on. But most of these might be best in a fuel fired kiln....... pretty hard on the elements. And if you fuel fire...... as Jim suggested.... fire mostly in oxidation.

best,

...............john

PS: And yes... you need GOOD ventilation for this tuff.
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

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#15 OffCenter

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Posted 22 April 2013 - 05:17 PM

I really appreciate all of the information!

Offcenter- thank you for the detailed response, you covered most of my questions that I have been going over in head-specifically about smoke. I'm really happy to hear that you've had success with it.


I think I will start off with coffee grounds and test a few saggars with differing amounts of ventilation to see what kind of results I can get.


Good luck. Let us know how it turns out.

Jim
E pur si muove.

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




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