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#1 Isculpt

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Posted 10 October 2010 - 08:44 AM

I have pit fired some pots after firing to cone 18 in an electric kiln, and I'm not happy with the color achieved in the pit firing. The pots are too consistently colored. Can I re-fire them in the electric kiln to remove the smoke effects and then pit fire them again? Can someone tell me how to produce the intense black smoke pattern without the entire pot going black? I want the mottled effect where the pot's clay color is still visible.

#2 Isculpt

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Posted 10 October 2010 - 11:13 AM

I have pit fired some pots after firing to cone 18 in an electric kiln, and I'm not happy with the color achieved in the pit firing. The pots are too consistently colored. Can I re-fire them in the electric kiln to remove the smoke effects and then pit fire them again? Can someone tell me how to produce the intense black smoke pattern without the entire pot going black? I want the mottled effect where the pot's clay color is still visible.



Sorry, this should have read cone 018!!

#3 Username

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Posted 10 October 2010 - 12:26 PM

You sure can refire them; I have done this often with pitfire or horsehair pieces I'm not happy with.
Two things I have noticed:
1. You may not get total "erasure" of your previous pitfiring. I'm often surprised how permanent some marks can be even if fired as high as ^6. This is not a problem, though, as the old marks will blend in with the new. The good news is that most of the old pitfiring marks will have burned out.
2. If you initially burnished the pots, some of it will have diminished after the refire. Again, not a big problem, but it does happen with each refire, and the clay becomes less porous I think, with each firing.



#4 Marcia Selsor

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Posted 10 October 2010 - 02:45 PM

Yes refire it.
READ RUSSEL FOUTS ARTICLE ON PIT FIRING IN ELECTRIC KILN:

http://ceramicartsda...ur-ceramic-art/

Full is interesting techniques. Or read this http://users.skynet....hed_Article.pdf

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#5 Username

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Posted 10 October 2010 - 03:25 PM

Wow, thanks, Marcia! These articles will give me so many more ideas to play with.
As a sidenote, we often raku fire in our electric kiln, and one time I thought, "now that we are finished raku firing, that kiln is now full of 1500 or 1200 degree heat, how can I use that?" So I started making aluminum saggars and putting them into the hot kiln, so that they saggar fire as the kiln cools. Works great, and I don't "waste" that heat any more. I suppose you could bake potatos or even cook a whole meal in there using the same technique; maybe a turkey?



#6 Marcia Selsor

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Posted 10 October 2010 - 08:53 PM

I love saggar firing in my raku kiln. Russel is a dear friend. Planning some saggar firings soon.
I just fire them in my raku kiln. That kiln seems more efficient than the electrics.

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#7 Isculpt

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Posted 11 October 2010 - 01:28 AM

I love saggar firing in my raku kiln. Russel is a dear friend. Planning some saggar firings soon.
I just fired them in my raku kiln. That kiln seems more efficient that the electrics.

Marcia



Thank you both for your suggestions. I'm self-taught, and I've read online articles about pit firing, but I can't seem to find answers to the questions that most concern me. I am really grateful for your help. And now I'm going to take shameless advantage of your knowledge and willingness to help by asking a few more questions, if I may.

I fire the pots, made from locally dug clay, to only 018 because I was told that the lower firing makes them more open to smoke effects. I assume that this is true?

The pots are burnished but remain a bit porous, so Russell's articles concerned me a bit. I would have thought that a waxy resist like lipstick or any of the other suggestions might leave a greasy-looking spot on the pot. Am I worried for nothing? I have already waxed some of the pots with a very diluted solution of wax resist because they weren't shiny enough, so I'm concerned about re-firing them. Will the wax just melt away without leaving greasy traces?

And speaking of shine, why do some of the pots come out of the pit fire very nice and shiny and some come out with a dull grey brown color and little shine? Is it due to the different fire temperatures or differences in the amount of burnishing or the timing of the burnishing? (It's hard to catch the pots when they are dry enough for burnishing, but just before they get too dry sometimes!) For the shinier, blacker pots, do I need more intense heat in the fire or less? I use pine bark for the smoking, and I've noticed that smothering the fire with lots of pine bark bit causes more blackening...

Am I to understand that one wraps the item in newspapers, then in foil and fires it to -- what temperature or cone? Would you get the same effect by lighting the paper through an opening in the foil?

The last time I tried to smoke fire in a metal trash can with holes drilled all around it, I had some cracking and breakage. Is there a way to minimize this? I'm not sure if the shifting of the items in the can as the combustibles burned down caused the damage or if the temperatures was the culprit.

For my sculptures, I'd like to get more interesting colors than just the smoked blacks and greys. I've read about throwing various chemicals and such into the fire, but I haven't been able to find out exactly when or how much. Do you have any basic information and simple suggestions?

Sorry for all the questions, but I warned you that I was shameless!;) thanks, Jayne

#8 Marcia Selsor

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Posted 11 October 2010 - 06:49 AM

First, I hope you bisque fired these before you are pit firing them. With terra sig, you may lose the shine if you fire over ^08 or 09.
018 is very low..I would say too low for good results.
Lipstick grease and wax should burn off. I don't think there would be much residue but I haven't tried lipstick , so I can't say. Read Russel's articles because he has the experience with these resists.
I saggar fire in saggars . He uses the tin foil in an electric kiln. The foil contains the smoke and doesn't bother the elements according to Russel. I had a student in Hawaii who saggar fired some sculpture. Using a saggar with a bit of sawdust, copper and salt, she got some nice blushes. Fired it to 1600 F hold for 20 minutes and cool. This was done in a raku kiln.

#9 OffCenter

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Posted 11 October 2010 - 08:50 AM

I have pit fired some pots after firing to cone 18 in an electric kiln, and I'm not happy with the color achieved in the pit firing. The pots are too consistently colored. Can I re-fire them in the electric kiln to remove the smoke effects and then pit fire them again? Can someone tell me how to produce the intense black smoke pattern without the entire pot going black? I want the mottled effect where the pot's clay color is still visible.


Re-firing the pot will remove most or all of the color from the pit firing (depending on how high you re-fire it) but the trick here is to re-fire it high enough to remove the color (or some of the color) without firing it too high to get good color in the next pit firing. Many years ago I had a student who got first place in a show in Denver by firing a pot black in a sagger in a reduction kiln then removing most of the black in an electric kiln then black again in the reduction kiln then back in the electric kiln. She may have even repeated the process again (I forget--it was in the 70's). But the pot had an incredible richness of color. We called it "color" but it was really just black, white, and shades of gray.

Jim
E pur si muove.

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

#10 Isculpt

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Posted 11 October 2010 - 09:52 AM


I have pit fired some pots after firing to cone 18 in an electric kiln, and I'm not happy with the color achieved in the pit firing. The pots are too consistently colored. Can I re-fire them in the electric kiln to remove the smoke effects and then pit fire them again? Can someone tell me how to produce the intense black smoke pattern without the entire pot going black? I want the mottled effect where the pot's clay color is still visible.


Re-firing the pot will remove most or all of the color from the pit firing (depending on how high you re-fire it) but the trick here is to re-fire it high enough to remove the color (or some of the color) without firing it too high to get good color in the next pit firing. Many years ago I had a student who got first place in a show in Denver by firing a pot black in a sagger in a reduction kiln then removing most of the black in an electric kiln then black again in the reduction kiln then back in the electric kiln. She may have even repeated the process again (I forget--it was in the 70's). But the pot had an incredible richness of color. We called it "color" but it was really just black, white, and shades of gray.

Jim


Thanks so much, Jim, for this encouragement. I understand the concept of "high enough to burn off the color, but not too high to get good color". Can you please take a stab at guessing appropriate cones? I am using hand dug clay from South Carolina, so I wouldn't think it can take a high cone fire. Jayne

#11 OffCenter

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Posted 11 October 2010 - 10:18 AM



I have pit fired some pots after firing to cone 18 in an electric kiln, and I'm not happy with the color achieved in the pit firing. The pots are too consistently colored. Can I re-fire them in the electric kiln to remove the smoke effects and then pit fire them again? Can someone tell me how to produce the intense black smoke pattern without the entire pot going black? I want the mottled effect where the pot's clay color is still visible.


Re-firing the pot will remove most or all of the color from the pit firing (depending on how high you re-fire it) but the trick here is to re-fire it high enough to remove the color (or some of the color) without firing it too high to get good color in the next pit firing. Many years ago I had a student who got first place in a show in Denver by firing a pot black in a sagger in a reduction kiln then removing most of the black in an electric kiln then black again in the reduction kiln then back in the electric kiln. She may have even repeated the process again (I forget--it was in the 70's). But the pot had an incredible richness of color. We called it "color" but it was really just black, white, and shades of gray.

Jim


Thanks so much, Jim, for this encouragement. I understand the concept of "high enough to burn off the color, but not too high to get good color". Can you please take a stab at guessing appropriate cones? I am using hand dug clay from South Carolina, so I wouldn't think it can take a high cone fire. Jayne


I'd try a cone 016 in an electric to remove color then something like 015 in the next pit firing. 018 again may work but it has been my experience that the firing to remove color works best if a little above the original firing and then the re-fire a little above that. My guess is that you can go a lot higher before you have to start worrying about the clay taking the heat.
E pur si muove.

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

#12 Marcia Selsor

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Posted 13 October 2010 - 07:59 AM

My saggar firings are at 1600 which is about ^012. But I do bisque to ^09 first.
Add lots of salt, copper carbonate or sulfate, Copper wires are interesting..scraps from electricians,
experiment.
Marcia

#13 Pam S

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Posted 22 October 2010 - 02:08 PM

This is something I would love to try. What clay bodies are you using? Also, can anyone point me towards more info on using foil as a saggar?

"Saving just one dog won't change the world, but it surely will change the world for that one dog."


#14 Marcia Selsor

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Posted 22 October 2010 - 08:26 PM

I use Coleman Porcelain and a ball clay terra sig.
Marcia





#15 Marcia Selsor

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Posted 24 October 2010 - 07:29 AM

Pam,
Russel's articles are available here. They are the best source I know for foil saggars.
July/August issues of 2007 and 2009 (or 6 and 8)

You can find both articles herehttp://users.skynet....ts/resource.htmin PDF format.


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#16 MMB

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Posted 16 December 2010 - 11:21 AM

Figured Id ask this question here rather than start a new thread. Pit fire related. From what everyone says here I might bisque my work to high (just to 06-04 range). I havent been too worried about burnishings although in my next firing I have an assortment of burnished and non burnished. I dont remember where I was at online but the artist mentioned how he though that some of his more beautiful work came out from non burnished pots. Being that that is the artists view point and not mine I still want to have a go at it. To the point though...Someone mentioned once that banana peels were a good addition because of the amount of potassium during the burn. Do you think this could be achieve with the simple use of drug store potassium pills crushed up? Or do you think that banana peels is successful because of it being something more burnable than just dust? Just trying a to work out which avenues and sample tests Im going to try in my next fire.




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