BJ Clark | Stinking Desert Ceramics on thu 10 nov 05
Tig,
The act of creating a reduction atmosphere in a non-combustion style kiln i=
s
used in other industries quite often.
Research glowbar kilns. They are usually Silicon Carbide glow rods
(elements) and purge all oxygen from the atmosphere in the kiln with
hydrogen.
They have been discussed some before on this list. Few years ago if I
recall. *Might* be in the archives.
BJ Clark
On 11/10/05, Tig Dupre wrote:
>
> Dear Mudbuds,
>
> Our beloved Ivor Lewis posted something a while back that got me to
> thinking. If I remember correctly, he said (casually, in passing) that th=
e
> introduction of an inert gas, such as argon, could cause reduction in an
> electric kiln.
>
> In mulling that one over, I thought about the process of reduction as
> being the removal of chemical oxygen in a glaze, to cause a color change.=
We
> get beautiful celadons, and copper reds ONLY through reduction, yes?
>
> But NORMAL reductive processes involve the addition of carbon (unburnt
> fuel) to the atmosphere, causing oxygen to combine with carbon to produce
> carbon dioxide and carbon monoxide.
>
> Why wouldn't the addition of argon cause a similar effect? And what effec=
t
> would it have on the elements of an electric kiln? We usually do not perf=
orm
> reduction in a standard electric kiln because it quickly oxidizes the
> elements, shortening their life considerably.
>
> Argon comes in handy canisters, and it wouldn't take a bunch of
> engineering to make an attachment for the introduction of a gas to the ki=
ln
> at the appropriate moment.
>
> What other gasses might be used? Does anyone find this line of thinking
> REALLY strange? At this point, it is merely a curiosity for me, only beca=
use
> I don't have the resources to experiment much.
>
> Any opinions?
>
> Tig Dupre
> in Port Orchard, Washington, USA
>
>
> _________________________________________________________________________=
_____
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
--
BJ Clark
Stinking Desert Ceramics
bjclark@stinkingdesert.com
www.stinkingdesert.com
Tig Dupre on thu 10 nov 05
Dear Mudbuds,
Our beloved Ivor Lewis posted something a while back that got me to thinking. If I remember correctly, he said (casually, in passing) that the introduction of an inert gas, such as argon, could cause reduction in an electric kiln.
In mulling that one over, I thought about the process of reduction as being the removal of chemical oxygen in a glaze, to cause a color change. We get beautiful celadons, and copper reds ONLY through reduction, yes?
But NORMAL reductive processes involve the addition of carbon (unburnt fuel) to the atmosphere, causing oxygen to combine with carbon to produce carbon dioxide and carbon monoxide.
Why wouldn't the addition of argon cause a similar effect? And what effect would it have on the elements of an electric kiln? We usually do not perform reduction in a standard electric kiln because it quickly oxidizes the elements, shortening their life considerably.
Argon comes in handy canisters, and it wouldn't take a bunch of engineering to make an attachment for the introduction of a gas to the kiln at the appropriate moment.
What other gasses might be used? Does anyone find this line of thinking REALLY strange? At this point, it is merely a curiosity for me, only because I don't have the resources to experiment much.
Any opinions?
Tig Dupre
in Port Orchard, Washington, USA
steve graber on thu 10 nov 05
reduction is a chemistry term meaning to reduce an element from the chemical system. in the pottery world this is usually meaning oxygen. other materials can be added to trade places with available oxygen, but the overall complexity of a firing goes up trying this.
in the metal heat treating world or metal brazing (higher level soldering parts together) they often purge the work piece with nitrogen, helium, and one case i saw used hydrogen. the hydrogen brazed parts were exceptional in final part quality. purging parts with helium left some discolorations.
if you want, try nitrogen, helium, but please stay away from messing with the hydrogen...
see ya
steve
Tig Dupre wrote:Dear Mudbuds,
Our beloved Ivor Lewis posted something a while back that got me to thinking. If I remember correctly, he said (casually, in passing) that the introduction of an inert gas, such as argon, could cause reduction in an electric kiln.
In mulling that one over, I thought about the process of reduction as being the removal of chemical oxygen in a glaze, to cause a color change. We get beautiful celadons, and copper reds ONLY through reduction, yes?
But NORMAL reductive processes involve the addition of carbon (unburnt fuel) to the atmosphere, causing oxygen to combine with carbon to produce carbon dioxide and carbon monoxide.
Why wouldn't the addition of argon cause a similar effect? And what effect would it have on the elements of an electric kiln? We usually do not perform reduction in a standard electric kiln because it quickly oxidizes the elements, shortening their life considerably.
Argon comes in handy canisters, and it wouldn't take a bunch of engineering to make an attachment for the introduction of a gas to the kiln at the appropriate moment.
What other gasses might be used? Does anyone find this line of thinking REALLY strange? At this point, it is merely a curiosity for me, only because I don't have the resources to experiment much.
Any opinions?
Tig Dupre
in Port Orchard, Washington, USA
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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Lester Haworth on thu 10 nov 05
Tig,
I think this is a great question. We all know the strong attraction of
carbon to oxygen.
I don't think argon would be as attracted to oxygen. Seems I read somewhere
that the attraction is not as strong but I could be wrong?
Interesting thought.
Les H.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Tig Dupre
Sent: Thursday, November 10, 2005 7:47 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Non-Carbon Reduction
Dear Mudbuds,
Our beloved Ivor Lewis posted something a while back that got me to
thinking. If I remember correctly, he said (casually, in passing) that the
introduction of an inert gas, such as argon, could cause reduction in an
electric kiln.
In mulling that one over, I thought about the process of reduction as being
the removal of chemical oxygen in a glaze, to cause a color change. We get
beautiful celadons, and copper reds ONLY through reduction, yes?
But NORMAL reductive processes involve the addition of carbon (unburnt fuel)
to the atmosphere, causing oxygen to combine with carbon to produce carbon
dioxide and carbon monoxide.
Why wouldn't the addition of argon cause a similar effect? And what effect
would it have on the elements of an electric kiln? We usually do not
perform reduction in a standard electric kiln because it quickly oxidizes
the elements, shortening their life considerably.
Argon comes in handy canisters, and it wouldn't take a bunch of engineering
to make an attachment for the introduction of a gas to the kiln at the
appropriate moment.
What other gasses might be used? Does anyone find this line of thinking
REALLY strange? At this point, it is merely a curiosity for me, only
because I don't have the resources to experiment much.
Any opinions?
Tig Dupre
in Port Orchard, Washington, USA
____________________________________________________________________________
__
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Patricia Dailey on fri 11 nov 05
Hi,
Margery Clinton in her Lustres book uses a nitrogen purge after her usual gas
reduction. The kiln was designed for her, and the nitrogen purge was to vent the
unfired gases from her kiln in much the same way they use nitrogen purges in
Silicon Valley to keep the etching of silicon wafers from flaming or other impurities. I
wonder if it added to her total reduction by removing not just the gases, but also any
remaining oxygen.
Just a thought.
Patricia Dailey
skiasonaranthropos@FSMAIL.NET on fri 11 nov 05
Hello Tig,
Reduction firing in an electric kiln is not only possibly but is
undertaken. One technique is to scrub a CO2 gas feed through methanol; due
to some basic chemistry this produces a suitably reducing gas mixture
Regards,
Antony
Lee Love on fri 11 nov 05
On 2005/11/11 22:26:34, BJ Clark | Stinking Desert Ceramics wrote:
> The act of creating a reduction atmosphere in a non-combustion style
kiln
> is used in other industries quite often.
They use the glowbar type kilns here in Japan. They are more common
than the coil type elements.
I met a guy from near Shigaraki at the Mashiko the fall
Tokiichi (Pottery festival, he was two booths down from my spot), whose
work was reduction pots that even had iron spots through the white
glaze. I thought for sure, his work was gas or wood fired. But
actually, what he does to get reduction is put a sagger in his electric
kiln, fills it with charcoal and covers the sagger tightly. The
burning charcoal sucks the oxygen out of the electric kiln. I
suppose you want to make sure the kiln is closed up tightly.
Seemed like a very simple method.
--
Lee Love
in Mashiko, Japan http://mashiko.org
http://seisokuro.blogspot.com/ My Photo Logs
"Simplicity is the ultimate sophistication."
--Leonardo da Vinci
Fredrick Paget on fri 11 nov 05
Before anyone starts using hydrogen consider this.
Hydrogen and air form an explosive mixture over a wide range of
concentrations of hydrogen in the air.
Hydrogen is used in industrial kilns but they are designed to keep
air out of the kiln. The ones we had at Sylvania Lighting Products
had a pilot burner at the upward swinging front door that lit the
hydrogen as it came out the door. The pure hydrogen inside won't burn
and the kiln was a long square tube (muffle kiln) so if perchance it
did blow it puffed out the back.
You can use a mix of 5 percent hydrogen in an inert gas to get
reduction since that won't burn, but you better know what you are
doing.
--
From Fred Paget,
Marin County, CA, USA
fredrick@well.com
Charter Member Potters Council
Ivor and Olive Lewis on tue 15 nov 05
Dear Fredrick Paget,=20
I am not sure if anyone has suggested using Hydrogen. I know I have not, =
nor would I. However, your post prompts me to say that in some =
industrial situations Cracked Ammonia us used as a reducing atmosphere.
Yes, Hydrogen atmosphere furnaces are pretty toey critters if not =
handled with care.
Best regards,
Ivor.
Ivor and Olive Lewis on tue 15 nov 05
Dear Anthony,
I would be reluctant to introduce Carbon dioxide into an electric kiln =
without having an efficient means to collect and dispose of the exhaust =
from the kiln.
The reaction you are speaking of, the decomposition of Carbon Dioxide, =
creates Carbon Monoxide, a colourless, odourless, tasteless gas that is =
highly toxic even if only inhaled for a short period of time. The =
decomposition of Carbon Dioxide also releases Oxygen so it may, to some =
degree, be counter productive.
My preferences are Nitrogen or Argon.
The thing people need to understand it that it is the Partial Pressure =
of Oxygen which we have to control to make the reduction reaction of =
these oxides happen
Best regards, Ivor
skiasonaranthropos@FSMAIL.NET on tue 15 nov 05
Hello Ivor,
You=92re right of course that CO is evolved and that an extraction or good
ventilation is recommended, however I posted simply to highlight that
electric reduction is possible. Also this is not theoretical as such kilns
do exist, are used safely and the atmosphere is controllable & consistent,
something that perhaps other suggestions may not offer
Kind regards,
Antony
Tig Dupre on tue 15 nov 05
Dear Mudbuds,
Many thanks to all who offered opinions, explanations, and critical analysis of my question on creating a reduction atmosphere without adding carbon. This is the absolute COOLEST forum in the entire Blogosphere!
Sure do love all youse!
Thanks again,
Tig Dupre
in CHILLY Port Orchard, Washington, USA
Lee Love on tue 15 nov 05
On 2005/11/11 22:26:34, BJ Clark | Stinking Desert Ceramics wrote:
> The act of creating a reduction atmosphere in a non-combustion style
kiln
> is used in other industries quite often.
They use the glowbar type kilns here in Japan. They are more common
than the coil type elements.
I met a guy from near Shigaraki at the Mashiko the fall
Tokiichi (Pottery festival, he was two booths down from my spot), whose
work was reduction pots that even had iron spots through the white
glaze. I thought for sure, his work was gas or wood fired. But
actually, what he does to get reduction is put a sagger in his electric
kiln, fills it with charcoal and covers the sagger tightly. The
burning charcoal sucks the oxygen out of the electric kiln. I
suppose you want to make sure the kiln is closed up tightly.
Seemed like a very simple method.
--
Lee Love
in Mashiko, Japan http://mashiko.org
http://seisokuro.blogspot.com/ My Photo Logs
"Simplicity is the ultimate sophistication."
--Leonardo da Vinci
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