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Obvara Firing Technique

Alternative firing surfaces

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#21 Evelyne Schoenmann

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Posted 30 July 2013 - 03:17 AM

 

 

 

Just saw this post, so please ignore my asking about the "witch's brew" in my p.m. Marcia. Thank you very much for sharing the receipt. Will sure try it some day... Do you think I can get 1650F in a pit? Want to try the obvara technique also in a pit or a drum instead of a kiln. Taking out the works after, say, 4 hours of pit firing....?
 
Evelyne

I am firing in my small raku kiln which is a little taller than 2/3 of an oil drum. I am thinking of making a smaller one for tests and simple firings. The kiln reaches 1650 in about 45 minutes if I hold back and am not fighting the wind.
Marcia

 

 
So you don't think I can do Obvara in an open fire pit?M
Marcia
 
Evelyne

 

If you can get to 1650 F go for it!
I think you would need to stoke a bit.Manolo Sala (Spain) gets copper fluxing in his pit firing of slab, so use a pyrometer and see how hot it really gets.
Marcia

 

 

Will sure try it one day! Will keep you in the loop (and will google Manolo Sala...). Thanks Marcia!

 

Evelyne


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#22 Marcia Selsor

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Posted 30 July 2013 - 06:30 AM

I 've been playing with Obvara for a little over a year now, that is the recipe.  Approximate amounts is fine,  I have found slight differences in different flours, but not much.  You may want to have a beer on hand to "liven" up the mixture if it looses it fizz or you get delayed a day or two.

I saw that one of the you tubes was you. Thanks for the tip about the beer. The solution smells like a kegger aftermath.I am having fun with the additives to the clay bodies. I find that has quite a lot to do with attracting the markings.
There are quite a few you tubes out there.I am really enjoying doing this.
Marcia

#23 Marcia Selsor

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Posted 30 July 2013 - 06:33 AM

Just saw this post, so please ignore my asking about the "witch's brew" in my p.m. Marcia. Thank you very much for sharing the receipt. Will sure try it some day... Do you think I can get 1650F in a pit? Want to try the obvara technique also in a pit or a drum instead of a kiln. Taking out the works after, say, 4 hours of pit firing....?
 
Evelyne

I am firing in my small raku kiln which is a little taller than 2/3 of an oil drum. I am thinking of making a smaller one for tests and simple firings. The kiln reaches 1650 in about 45 minutes if I hold back and am not fighting the wind.
Marcia

 
So you don't think I can do Obvara in an open fire pit?M
Marcia
 
Evelyne

If you can get to 1650 F go for it!
I think you would need to stoke a bit.Manolo Sala (Spain) gets copper fluxing in his pit firing of slab, so use a pyrometer and see how hot it really gets.
Marcia

 
Will sure try it one day! Will keep you in the loop (and will google Manolo Sala...). Thanks Marcia!
 
Evelyne

Manolo Salas. He is a very excellent ceramic artist with a day job as a tech in a big ceramics factory in Onda.
He developed a glow in the dark glaze for a night club tiled ceiling in Barcelona. I have a test piece on a key chain that he gave me.
Marcia

#24 Bob Coyle

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Posted 30 July 2013 - 02:24 PM

As a chemist, I can't see any real reason to ferment the brew you dunk the pots in. Any kind of foaming from the CO2 would not seem to make much difference. The oxidation smoking of the charred organics in the mix is what gives the color.

Has anyone tried it without fermentation?

 

It seems like you could get even more wild effects by adding other chemical to the mix like copper carb or iron chloride. Also thickening with gelatin or even adding cooked angel hair noodles stirred up so they would adhere to the pot when you pulled it out 

 

From the videos I've seen, It looks like the real trick is how long you immerse and quench the piece, and what the temp it actually was when it went in. Some of the pieces in the videos were a heck of a lot cooler than 1600 F.  It looked like, if the pots were cooler, then the patina was more brown and it they were put in real hot, the patina was black, just due to carbon formation. Some of he videos were pretty bad though. Hard to see how how hot the pots were though they didn't seem to be glowing like you would expect at 1600F.

 

I've done a lot of pit fires and 1600F is probably hard to reach but I'm not sure you have to be even very close. I would bet that you can get the same effect even at  eight or nine hundred. It would be worth a try.



#25 Up in Smoke Pottery

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Posted 31 July 2013 - 06:12 AM

 

I 've been playing with Obvara for a little over a year now, that is the recipe.  Approximate amounts is fine,  I have found slight differences in different flours, but not much.  You may want to have a beer on hand to "liven" up the mixture if it looses it fizz or you get delayed a day or two.

I saw that one of the you tubes was you. Thanks for the tip about the beer. The solution smells like a kegger aftermath.I am having fun with the additives to the clay bodies. I find that has quite a lot to do with attracting the markings.
There are quite a few you tubes out there.I am really enjoying doing this.
Marcia

 

Your welcome, its been fun to play with and people seem to understand this better than other alternative processes.  We've tried various flours and other ingredients including the traditional beet juice for coloring.  Are you going to demo this in Minneapolis in October?  Wish I could make it, but unable to get the time off this year.

 

Here is the link to the youtube video if anyone wants to watch it, or it's on our web site also.

 

http://www.youtube.c...h?v=Fr8qnufIazk

 

Chad


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#26 Marcia Selsor

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Posted 31 July 2013 - 07:29 AM

Yes, I am doing this in Oct.in Minneapolis. What did the beet juice do? I love beet juice color and even ate beets baby food when I was a baby. (whew that is literally ancient history).
I see all those pieces in the link have brownish tint. very nice surfaces too. Mine are black and white. I was using porcelain scraps with 5 different additives to the clay body: coffee grounds, perlite, kitty litter, sawdust, and brass filings. I liked the perlite the best.The kitty litter didn't work as well. I have used it before a long time ago. This modern fragrant absorbent stuff didn't hold up.I think the brass filings could be rolled onto the surface. All these were had built.

The you tube above shows the process although my results were different from these. These look like they were polished with terra sig.

Benzine, using a glaze would prohibit the absorption of the brew and carbon. But as always, try it and see.
Marcia

#27 Marcia Selsor

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Posted 31 July 2013 - 09:08 AM

As a chemist, I can't see any real reason to ferment the brew you dunk the pots in. Any kind of foaming from the CO2 would not seem to make much difference. The oxidation smoking of the charred organics in the mix is what gives the color.
Has anyone tried it without fermentation?
 
It seems like you could get even more wild effects by adding other chemical to the mix like copper carb or iron chloride. Also thickening with gelatin or even adding cooked angel hair noodles stirred up so they would adhere to the pot when you pulled it out 
 
From the videos I've seen, It looks like the real trick is how long you immerse and quench the piece, and what the temp it actually was when it went in. Some of the pieces in the videos were a heck of a lot cooler than 1600 F.  It looked like, if the pots were cooler, then the patina was more brown and it they were put in real hot, the patina was black, just due to carbon formation. Some of he videos were pretty bad though. Hard to see how how hot the pots were though they didn't seem to be glowing like you would expect at 1600F.
 
I've done a lot of pit fires and 1600F is probably hard to reach but I'm not sure you have to be even very close. I would bet that you can get the same effect even at  eight or nine hundred. It would be worth a try.

I had 10 pieces in the kiln. I could get 2 out and through the process before the kiln dropped below 1500. Then the process didn't seem to work. A bubbly Scum solidified on the surface.So 1650 is the best temp. from my experience.
Marcia

#28 Up in Smoke Pottery

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Posted 31 July 2013 - 02:50 PM

Yes, I am doing this in Oct.in Minneapolis. What did the beet juice do? I love beet juice color and even ate beets baby food when I was a baby. (whew that is literally ancient history).
I see all those pieces in the link have brownish tint. very nice surfaces too. Mine are black and white. I was using porcelain scraps with 5 different additives to the clay body: coffee grounds, perlite, kitty litter, sawdust, and brass filings. I liked the perlite the best.The kitty litter didn't work as well. I have used it before a long time ago. This modern fragrant absorbent stuff didn't hold up.I think the brass filings could be rolled onto the surface. All these were had built.

The you tube above shows the process although my results were different from these. These look like they were polished with terra sig.

Benzine, using a glaze would prohibit the absorption of the brew and carbon. But as always, try it and see.
Marcia

 the beet juice and or sauerkraut juice (red) is supposed to stain the mixture giving more reddish brown hues.  I have not had any success with this, I may have to puree the whole can(s) versus just straining the juice off.

 

In the video none of the pieces were terra sigg'd.  I have found it occasionally flakes off in the process, and when it does stay I haven't noticed enough of a difference to include that step.

 

Chad


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#29 Marcia Selsor

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Posted 31 July 2013 - 05:33 PM

Yes, I am doing this in Oct.in Minneapolis. What did the beet juice do? I love beet juice color and even ate beets baby food when I was a baby. (whew that is literally ancient history).
I see all those pieces in the link have brownish tint. very nice surfaces too. Mine are black and white. I was using porcelain scraps with 5 different additives to the clay body: coffee grounds, perlite, kitty litter, sawdust, and brass filings. I liked the perlite the best.The kitty litter didn't work as well. I have used it before a long time ago. This modern fragrant absorbent stuff didn't hold up.I think the brass filings could be rolled onto the surface. All these were had built.

The you tube above shows the process although my results were different from these. These look like they were polished with terra sig.

Benzine, using a glaze would prohibit the absorption of the brew and carbon. But as always, try it and see.
Marcia

 the beet juice and or sauerkraut juice (red) is supposed to stain the mixture giving more reddish brown hues.  I have not had any success with this, I may have to puree the whole can(s) versus just straining the juice off.
 
In the video none of the pieces were terra sigg'd.  I have found it occasionally flakes off in the process, and when it does stay I haven't noticed enough of a difference to include that step.
 
Chad

They came out really smooth. Nice brown color.

Marcia

#30 Marcia Selsor

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Posted 01 August 2013 - 08:08 AM

Made six new clay tests for my next Obvara firing. I have jury duty starting next week, so the firing will be on a weekend in the future.Additives include rice, macaroni, paper and perlite.The resulting pitting seems to attract the carbon spotting. I like that.

Marcia

#31 Marcia Selsor

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Posted 03 August 2013 - 12:33 PM

There are several more you tube videos out there on firing obvara. Jane Jermyn has been doing workshops in Europe. Her site lists several more ceramicist using obvara.



Jose Ramos


Marcia

#32 Benzine

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Posted 03 August 2013 - 08:39 PM

Great videos.  Thanks Marcia.  I am very tempted to try this.  I still need to get my Raku kiln altered a bit.

 

How was it, that in the second video, he got one half to turn brown, and the other black?


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#33 Marcia Selsor

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Posted 04 August 2013 - 09:10 AM

Maybe its the temperature when they hit the solution. Clay body?
Can't say. Up in Smoke's pieces are brown. Mine were black mostly.
what's up with your raku kiln?

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#34 Benzine

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Posted 04 August 2013 - 09:19 AM

Maybe its the temperature when they hit the solution. Clay body?
Can't say. Up in Smoke's pieces are brown. Mine were black mostly.
what's up with your raku kiln?

Marcia

It wasn't quite getting up to temperature.  We've talked before, about my needing to possibly widen both the intake, and exhaust ports.  I just haven't got to it, as I haven't fired in months.  The kiln gets to about 1600 F currently, and just hangs out there.  Plus, it takes a while to get there, longer than the time it takes the average, similar style Raku kiln to fire anyway.  The glaze is seems to be just below maturity, when the kiln temperature plateaus.


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#35 jchas

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Posted 07 August 2013 - 09:58 AM

I started using this technique about a year ago. I am hooked and I am looking for as much as I can about the history.  I have been on Jane's Facebook page, but I can't find any specifics.  If anyone has any information on where to get published information and history, I would love that.  I will upload a few pictures...as soon as I figure that out.  Attached File  IMG_9184L.jpg   79.05KB   2 downloadsAttached File  IMG_9171L.jpg   48.36KB   3 downloadsAttached File  IMG_9193L.jpg   49.42KB   2 downloadsAttached File  IMG_9269L.jpg   52.73KB   3 downloadsAttached File  IMG_9278L.jpg   52.78KB   3 downloadsAttached File  IMG_9059L.jpg   98.69KB   2 downloadsAttached File  IMG_9023_4L.jpg   90.9KB   0 downloadsAttached File  IMG_9111L.jpg   77.35KB   2 downloadsAttached File  IMG_9046L.jpg   96.45KB   1 downloadsAttached File  IMG_9046L.jpg   96.45KB   1 downloadsAttached File  IMG_9170L.jpg   44.61KB   2 downloadsAttached File  IMG_9212L.jpg   59.24KB   2 downloads



#36 trina

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Posted 08 August 2013 - 06:22 AM

wow those are wonderful! I have not tried this technique but it's really tempting me T

#37 Marcia Selsor

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Posted 08 August 2013 - 07:57 AM

you are getting some great surface effects for your imagery. Thanks for posting.
Marcia

#38 Wyndham

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Posted 10 August 2013 - 09:09 AM

Marcia, what's the percentage of pieces breaking from thermal shock in the first or second dunking?

Wyndham

 

Edit, this could make some great Bonsai pots, hummn



#39 Marcia Selsor

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Posted 10 August 2013 - 05:55 PM

Marcia, what's the percentage of pieces breaking from thermal shock in the first or second dunking?
Wyndham
 
Edit, this could make some great Bonsai pots, hummn

for me , zero.

#40 Pugaboo

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Posted 10 August 2013 - 10:41 PM

Marcia - beautiful as always!
The world is but a canvas to the imagination - Henry David Thoreau




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