wjskw@BELLSOUTH.NET on wed 10 nov 04
I've been thinking about the mayor's gas reduction for electric kiln
idea today. I use it, know others that do. Reduction is possible,
even in an ancient electric kiln (it's in the archives, look it up
if you have no idea what I'm on about.)
Has anyone experimented with using an inert gas for reduction in an
electric, gas or other fuel (wood? coal? oil?) environment?
Since the point of reduction is the displacement of oxygen in the
internal environment of the kiln while firing; couldn't a
non-explosive (inert) gas be substituted for the propane, injected
into a kiln interior and the atmosphere monitored with an oxyprobe
perhaps? Argon or CO2?
The reason I ask is that carbon dioxide (CO2) is an inert gas, sold
all over the place (cheap) in tanks for use in (drinking) soda
fountains, bars, restaurants etc. Relatively harmless (ok, no
environmental ozone damage anyway) readily available. I recently
watched the installation of a CO2 generator, supposed to replace the
tank of CO2 delivered on a regular basis. It works (according to
the tech doing the install, by drawing CO2 out of the air, much the
same way as a tree does. (I'm not a chemist; I know trees do that,
but not how they do.) The tech said that the CO2 generator could be
purchased or leased. That got me thinking.
Propane/natural gas scares the crap out of me. Has since I blew the
oven door off back in '67 and killed the kitchen table. I use it
because I dislike electric even more. While the propane reduction
system for electric kilns is safe (used properly), propane is still
a highly flammable, explosive gas. . I'm always VERY mindful of it
being on; it's called "keeping a wary eye..."
And what does dry ice (frozen CO2) do when heated to cone 10, since
it gassifies at room temp?
Anyone?
Wayne Seidl
Key West FL US
pdp1@EARTHLINK.NET on wed 10 nov 04
Hi Wayne,
I have wondered about this too.
Certainly any Bottled Gas will be expensive, relatively
anyway.
And likely too, anything as is introduced will tend to have
something of a cooling influence as it expands into a gas.
I have wondered about useing Water...which in becomeing
Steam of course would displace other Oxygen, but then, would
it chemically prodide Oxygen also? Likewise with Carbon
dioxide? Maybe not so good then...but I do not know on that.
Hmmmmm...what about Old Tires?
Now they would not only contribute to the heat, while
obligeingly produceing plenty of useful 'gasses' which will
support a reduction...but also, are cheap, easy to get, and
worthless otherwise. Too, lots of really pretty smoke I
would expect, to dramatise and punctuate the reduction
event's progress...
Whatcha think?
Phil
el ve
----- Original Message -----
From:
I've been thinking about the mayor's gas reduction for
electric kiln
idea today. I use it, know others that do. Reduction is
possible,
even in an ancient electric kiln (it's in the archives, look
it up
if you have no idea what I'm on about.)
Has anyone experimented with using an inert gas for
reduction in an
electric, gas or other fuel (wood? coal? oil?) environment?
Since the point of reduction is the displacement of oxygen
in the
internal environment of the kiln while firing; couldn't a
non-explosive (inert) gas be substituted for the propane,
injected
into a kiln interior and the atmosphere monitored with an
oxyprobe
perhaps? Argon or CO2?
The reason I ask is that carbon dioxide (CO2) is an inert
gas, sold
all over the place (cheap) in tanks for use in (drinking)
soda
fountains, bars, restaurants etc. Relatively harmless (ok,
no
environmental ozone damage anyway) readily available. I
recently
watched the installation of a CO2 generator, supposed to
replace the
tank of CO2 delivered on a regular basis. It works
(according to
the tech doing the install, by drawing CO2 out of the air,
much the
same way as a tree does. (I'm not a chemist; I know trees do
that,
but not how they do.) The tech said that the CO2 generator
could be
purchased or leased. That got me thinking.
Propane/natural gas scares the crap out of me. Has since I
blew the
oven door off back in '67 and killed the kitchen table. I
use it
because I dislike electric even more. While the propane
reduction
system for electric kilns is safe (used properly), propane
is still
a highly flammable, explosive gas. . I'm always VERY
mindful of it
being on; it's called "keeping a wary eye..."
And what does dry ice (frozen CO2) do when heated to cone
10, since
it gassifies at room temp?
Anyone?
Wayne Seidl
Key West FL US
Louis Katz on wed 10 nov 04
In Thailand as with lots of other third world countrys kilns have been
fired with tires. There was just a piece on npr about generating
electricity with them.
In Dankwean village as wood got very scarce in the late 80's tires were
used more and more. They burnt them at all temperatures consequently
they added to the pollution levels significantly. Had they waited until
the kilns were already very hot there would not have been much smoke
from them.But by the late 1980's they were mostly firing to a medium or
low temp and there was not much motivation to go to cone 9. The tires
did tend to give the pots a greener cast from their woodash, a mattish
alkaline earth rich-like ash surface.
Andy Martin reduced a wood kiln in Kansas City with a tire he rolled
into the ash pit. Apparently it made a big load of smoke, probably
dangerous levels in the kiln room, and trapped carbon in the glazes. A
small piece of tire lit in an open air studio will keep mosquitos and
Louis away. Tire was used as the starter for charcoal cooking fires
when I lived at Umdang Ceramics in Thailand and Katz' law of pessimism
is:
No matter where the fire is being started, Louis is downwind. Whatever
you do with those tires, remember I smell it.
Louis
On Nov 10, 2004, at 2:11 PM, pdp1@EARTHLINK.NET wrote:
> Hi Wayne,
>
>
> I have wondered about this too.
>
> Certainly any Bottled Gas will be expensive, relatively
> anyway.
>
> And likely too, anything as is introduced will tend to have
> something of a cooling influence as it expands into a gas.
>
> I have wondered about useing Water...which in becomeing
> Steam of course would displace other Oxygen, but then, would
> it chemically prodide Oxygen also? Likewise with Carbon
> dioxide? Maybe not so good then...but I do not know on that.
>
> Hmmmmm...what about Old Tires?
>
> Now they would not only contribute to the heat, while
> obligeingly produceing plenty of useful 'gasses' which will
> support a reduction...but also, are cheap, easy to get, and
> worthless otherwise. Too, lots of really pretty smoke I
> would expect, to dramatise and punctuate the reduction
> event's progress...
>
> Whatcha think?
>
>
> Phil
> el ve
>
>
>
>
> ----- Original Message -----
> From:
>
>
>
> I've been thinking about the mayor's gas reduction for
> electric kiln
> idea today. I use it, know others that do. Reduction is
> possible,
> even in an ancient electric kiln (it's in the archives, look
> it up
> if you have no idea what I'm on about.)
>
> Has anyone experimented with using an inert gas for
> reduction in an
> electric, gas or other fuel (wood? coal? oil?) environment?
>
> Since the point of reduction is the displacement of oxygen
> in the
> internal environment of the kiln while firing; couldn't a
> non-explosive (inert) gas be substituted for the propane,
> injected
> into a kiln interior and the atmosphere monitored with an
> oxyprobe
> perhaps? Argon or CO2?
>
> The reason I ask is that carbon dioxide (CO2) is an inert
> gas, sold
> all over the place (cheap) in tanks for use in (drinking)
> soda
> fountains, bars, restaurants etc. Relatively harmless (ok,
> no
> environmental ozone damage anyway) readily available. I
> recently
> watched the installation of a CO2 generator, supposed to
> replace the
> tank of CO2 delivered on a regular basis. It works
> (according to
> the tech doing the install, by drawing CO2 out of the air,
> much the
> same way as a tree does. (I'm not a chemist; I know trees do
> that,
> but not how they do.) The tech said that the CO2 generator
> could be
> purchased or leased. That got me thinking.
>
> Propane/natural gas scares the crap out of me. Has since I
> blew the
> oven door off back in '67 and killed the kitchen table. I
> use it
> because I dislike electric even more. While the propane
> reduction
> system for electric kilns is safe (used properly), propane
> is still
> a highly flammable, explosive gas. . I'm always VERY
> mindful of it
> being on; it's called "keeping a wary eye..."
>
> And what does dry ice (frozen CO2) do when heated to cone
> 10, since
> it gassifies at room temp?
>
> Anyone?
>
> Wayne Seidl
> Key West FL US
>
> _______________________________________________________________________
> _______
> 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.
>
>
http://falcon.tamucc.edu/~lkatz/
Fredrick Paget on wed 10 nov 04
>I've been thinking about the mayor's gas reduction for electric kiln
>idea today. I use it, know others that do. Reduction is possible,
>even in an ancient electric kiln (it's in the archives, look it up
>if you have no idea what I'm on about.)
>
>Has anyone experimented with using an inert gas for reduction in an
>electric, gas or other fuel (wood? coal? oil?) environment?
An inert gas like argon won't work because it IS inert. It does not
enter into chemical reactions and reduction is a chemical reaction.
If there is carbon present like from smoke, then steam will combine
with the carbon in the well known water gas reaction to give carbon
monoxide and hydrogen which are both active reducing agents.
Hmmmm! Water and old tires? Give it a try.
--
From Fred Paget, Marin County, California, USA
fredrick@well.com
Hank Murrow on wed 10 nov 04
On Nov 10, 2004, at 8:43 AM, wjskw@BELLSOUTH.NET wrote:
>
> Has anyone experimented with using an inert gas for reduction in an
> electric, gas or other fuel (wood? coal? oil?) environment?
>
> Since the point of reduction is the displacement of oxygen in the
> internal environment of the kiln while firing; couldn't a
> non-explosive (inert) gas be substituted for the propane, injected
> into a kiln interior and the atmosphere monitored with an oxyprobe
> perhaps? Argon or CO2?
Dear Wayne;
An admirable idea, and well worth try if you wish a neutral atmosphere.
For reduction, I believe you would need a more active agent to draw the
Oxygen away from the glaze oxides. Nevertheless, please report your
results if you try the neutral gas idea.
>
> The reason I ask is that carbon dioxide (CO2) is an inert gas, sold
> all over the place (cheap) in tanks for use in (drinking) soda
> fountains, bars, restaurants etc. Relatively harmless (ok, no
> environmental ozone damage anyway) readily available. I recently
> watched the installation of a CO2 generator, supposed to replace the
> tank of CO2 delivered on a regular basis. It works (according to
> the tech doing the install, by drawing CO2 out of the air, much the
> same way as a tree does. (I'm not a chemist; I know trees do that,
> but not how they do.) The tech said that the CO2 generator could be
> purchased or leased. That got me thinking.
I also believe that it is the carbon monoxide that is capturing the
oxygen during reduction, and additionally at high temperatures, the
hydrogen from water vapor(there is always some in gaseous fuels).
>
> Propane/natural gas scares the crap out of me. Has since I blew the
> oven door off back in '67 and killed the kitchen table. I use it
> because I dislike electric even more. While the propane reduction
> system for electric kilns is safe (used properly), propane is still
> a highly flammable, explosive gas. . I'm always VERY mindful of it
> being on; it's called "keeping a wary eye..."
As long as there is not a stoichiometric mixture (around 8_1 air to
fuel) , there can be no explosion, and propane will light of its own
accord as soon as it enters a red hot chamber. Just partially or fully
close the damper before adding the fuel, to prevent an explosion.
Hoping this assuages and informs,
Hank in Eugene
www.murrow.biz/hank
Ivor and Olive Lewis on thu 11 nov 04
Dear Wayne,
You ask <reduction in an
electric, gas or other fuel (wood? coal? oil?) environment? >> Look in
Margery Clinton's Book "Lustres" pp 57-59 "Lustre Kilns and their
design" and pp 65- 74.
An interesting summation.
Is Carbon Dioxide inert ? Perhaps not ! Yes, it may do nothing in the
sense of exploding or igniting. Yes, it can be used to displace Oxygen
or Air from a container. But is it inert in the sense of entering into
chemical reactions or stable in the sense that it will not decompose.
By the way, I thought reduction in a clay body or of a glaze
ingredient was achieved by removing Oxygen from the metallic part of
the compound using something for which Oxygen had a greater affinity,
like Carbon monoxide, Hydrogen, a hydrocarbon or Carbon.
You may find the following site of interest....
http://www.cof.com.au/Nernst.shtml Helps out with Oxyprobe values and
relates them to Atmospheric Pressure.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
----- Original Message -----
From:
To:
Sent: Thursday, 11 November 2004 3:13
Subject: Reduction environment and inert gases
I've been thinking about the mayor's gas reduction for electric kiln
idea today. I use it, know others that do. Reduction is possible,
even in an ancient electric kiln (it's in the archives, look it up
if you have no idea what I'm on about.)
Has anyone experimented with using an inert gas for reduction in an
electric, gas or other fuel (wood? coal? oil?) environment?
Since the point of reduction is the displacement of oxygen in the
internal environment of the kiln while firing; couldn't a
non-explosive (inert) gas be substituted for the propane, injected
into a kiln interior and the atmosphere monitored with an oxyprobe
perhaps? Argon or CO2?
The reason I ask is that carbon dioxide (CO2) is an inert gas, sold
all over the place (cheap) in tanks for use in (drinking) soda
fountains, bars, restaurants etc. Relatively harmless (ok, no
environmental ozone damage anyway) readily available. I recently
watched the installation of a CO2 generator, supposed to replace the
tank of CO2 delivered on a regular basis. It works (according to
the tech doing the install, by drawing CO2 out of the air, much the
same way as a tree does. (I'm not a chemist; I know trees do that,
but not how they do.) The tech said that the CO2 generator could be
purchased or leased. That got me thinking.
Propane/natural gas scares the crap out of me. Has since I blew the
oven door off back in '67 and killed the kitchen table. I use it
because I dislike electric even more. While the propane reduction
system for electric kilns is safe (used properly), propane is still
a highly flammable, explosive gas. . I'm always VERY mindful of it
being on; it's called "keeping a wary eye..."
And what does dry ice (frozen CO2) do when heated to cone 10, since
it gassifies at room temp?
Anyone?
Wayne Seidl
Key West FL US
______________________________________________________________________
________
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.
John Rodgers on thu 11 nov 04
Wayne,
I don't know if this information is of any value to you, but I used to
do a good bit of airbrush work, and I hated the noise a compressor made
in my studio. I opted out to use liquid CO2 to drive my air brush. There
is a special regulator that will allow the liquid CO2 to convert to a
gas for dispersal through the hose to the airbrush or other tool. Maybe
you could make use of liquid CO2 in some manner.
Someone mentioned old tires. Here's more detritus. A couple from
Australia stopped into my Alaska Studio one time, and in our
conversation I learned he was some sort of millionaire used tire tycoon.
He collected tires from around the world, and at his place in Australia
extracted the oil from them for recycling.
Regards,
John Rodgers
Chelsea, AL
wjskw@BELLSOUTH.NET wrote:
>I've been thinking about the mayor's gas reduction for electric kiln
>idea today. I use it, know others that do. Reduction is possible,
>even in an ancient electric kiln (it's in the archives, look it up
>if you have no idea what I'm on about.)
>
>Has anyone experimented with using an inert gas for reduction in an
>electric, gas or other fuel (wood? coal? oil?) environment?
>
>Since the point of reduction is the displacement of oxygen in the
>internal environment of the kiln while firing; couldn't a
>non-explosive (inert) gas be substituted for the propane, injected
>into a kiln interior and the atmosphere monitored with an oxyprobe
>perhaps? Argon or CO2?
>
>The reason I ask is that carbon dioxide (CO2) is an inert gas, sold
>all over the place (cheap) in tanks for use in (drinking) soda
>fountains, bars, restaurants etc. Relatively harmless (ok, no
>environmental ozone damage anyway) readily available. I recently
>watched the installation of a CO2 generator, supposed to replace the
>tank of CO2 delivered on a regular basis. It works (according to
>the tech doing the install, by drawing CO2 out of the air, much the
>same way as a tree does. (I'm not a chemist; I know trees do that,
>but not how they do.) The tech said that the CO2 generator could be
>purchased or leased. That got me thinking.
>
>Propane/natural gas scares the crap out of me. Has since I blew the
>oven door off back in '67 and killed the kitchen table. I use it
>because I dislike electric even more. While the propane reduction
>system for electric kilns is safe (used properly), propane is still
>a highly flammable, explosive gas. . I'm always VERY mindful of it
>being on; it's called "keeping a wary eye..."
>
>And what does dry ice (frozen CO2) do when heated to cone 10, since
>it gassifies at room temp?
>
>Anyone?
>
>Wayne Seidl
>Key West FL US
>
>______________________________________________________________________________
>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.
>
>
>
>
wjskw@BELLSOUTH.NET on thu 11 nov 04
Many thanks to all who pointed out that displacement of oxygen has
little (if anything) to do with reduction. I guess I have a lot
more studying to do.
(My partner always accuses me of being "Rube Goldberg" reincarnated)
Wayne Seidl
going off into the corner to wipe the egg off my face
William Melstrom on thu 11 nov 04
Wayne:
Crystalline glazier Alfred Stolken has successfully reduced using both
nitrogen and carbon dioxide. However, he thinks that it is too complicated,
and now just uses propane. You can contact him through his artistic
collaborator Ronni Lee at herrstolk@poetworld.net .
William Melstrom
www.handspiral.com
Wayne wrote:
Many thanks to all who pointed out that displacement of oxygen has
little (if anything) to do with reduction. I guess I have a lot
more studying to do.
Bruce Girrell on thu 11 nov 04
Ivor Lewis wrote:
> By the way, I thought reduction in a clay body or of a glaze
> ingredient was achieved by removing Oxygen from the metallic part of
> the compound using something for which Oxygen had a greater affinity,
> like Carbon monoxide, Hydrogen, a hydrocarbon or Carbon.
Ivor,
I didn't post anything to the list regarding reduction atmospheres because I
figured you'd jump all over that one, but you stated it rather tentatively,
so I'll state it more firmly:
Reduction of metallic oxides (iron oxide, copper oxide, etc.) in our glazes
is not accomplished by the displacement of oxygen from the kiln atmosphere.
It is accomplished exactly as Ivor stated, by having a highly reactive
component of the atmosphere surrounding the objet d'art (whether in a kiln
or a reduction barrel) that wants to combine with oxygen more than the metal
is capable of holding on to the oxygen as an oxide. In effect, the hot
carbon, carbon monoxide, free hydrogen, etc. "steals" the oxygen from the
metallic oxide resulting in the production of CO, CO2, H2O, etc.
The lack of oxygen in the kiln atmosphere is simply due to the fact that the
reactive components will happily eat up all of the oxygen in the air that it
can get to before doing the harder work of prying an oxygen free from the
metallic oxide.
Any questions?
Bruce "yes - you in the third row..." Girrell
pdp1@EARTHLINK.NET on thu 11 nov 04
Hi Wayne,
Me too...
I forgot or did not quite know to begin with, that the
reduction process is a Chemical affair, rather than that the
Oxygen may be simply displaced or lessened from other gasses
as in simpler fires.
An excellent mention my friend Bruce sent me off list:
"Displacing oxygen is not how it works. In order for
reduction to occur you
need a very reactive, oxygen hungry molecule like carbon
monoxide or
elemental hydrogen - something that wants oxygen so badly
that it will steal
it from the metal oxides that we use like iron oxide or
copper oxide,
thereby reducing the metal to a lower valence state. The
reason that there
is no oxygen in a reducing environment is not because it has
been displaced,
but because it has reacted with the oxygen hungry molecules.
Only after the
relatively easily reacting free oxygen in the kiln
atmosphere has been used
up will the reactive gases go after the much more difficult
to liberate
oxygen bound up as oxides."
I am blotting my 'egg' as we speak.
Someday, when I have my own Kiln, I will remember all these
many Posts about all the things I do not know, and I will
print out a few reems of them from the archives and assemble
them into a Book I can immerse myself in for weeks.
Best wishes,
Sorry if I seemed moody lately, or blue...
Autum...lots of memories, people-troubles from
misunderstandings that waste precious trusts or ease, too
easily...and too much to do so far as responsibilities...and
me not adequate to do all of it without some of it getting
neglected or goofed up.
Phil
el ve
----- Original Message -----
From:
Many thanks to all who pointed out that displacement of
oxygen has
little (if anything) to do with reduction. I guess I have a
lot
more studying to do.
(My partner always accuses me of being "Rube Goldberg"
reincarnated)
Wayne Seidl
going off into the corner to wipe the egg off my face
claybair on thu 11 nov 04
Yesterday on NPR
there was a discussion about
how tires are being used to
produce energy.
Apparently they are shredded
then put in a furnace to 3000 F.
According to the reporter it is a
much cleaner burn.
So I was thinking.... why waste
the heat??? Imagine the firings
one could get out of harnessing
some of that heat!
There were additional uses for tires
mentioned. Tires will become such
a valued resource that
the supply will be gone in 20 years.
Who wooda thunk?
Gayle Bair
Bainbridge Island, WA
http://claybair.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of John Rodgers
Sent: Wednesday, November 10, 2004 10:25 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Reduction environment and inert gases
Wayne,
I don't know if this information is of any value to you, but I used to
do a good bit of airbrush work, and I hated the noise a compressor made
in my studio. I opted out to use liquid CO2 to drive my air brush. There
is a special regulator that will allow the liquid CO2 to convert to a
gas for dispersal through the hose to the airbrush or other tool. Maybe
you could make use of liquid CO2 in some manner.
Someone mentioned old tires. Here's more detritus. A couple from
Australia stopped into my Alaska Studio one time, and in our
conversation I learned he was some sort of millionaire used tire tycoon.
He collected tires from around the world, and at his place in Australia
extracted the oil from them for recycling.
Regards,
John Rodgers
Chelsea, AL
wjskw@BELLSOUTH.NET wrote:
>I've been thinking about the mayor's gas reduction for electric kiln
>idea today. I use it, know others that do. Reduction is possible,
>even in an ancient electric kiln (it's in the archives, look it up
>if you have no idea what I'm on about.)
>
>Has anyone experimented with using an inert gas for reduction in an
>electric, gas or other fuel (wood? coal? oil?) environment?
>
>Since the point of reduction is the displacement of oxygen in the
>internal environment of the kiln while firing; couldn't a
>non-explosive (inert) gas be substituted for the propane, injected
>into a kiln interior and the atmosphere monitored with an oxyprobe
>perhaps? Argon or CO2?
>
>The reason I ask is that carbon dioxide (CO2) is an inert gas, sold
>all over the place (cheap) in tanks for use in (drinking) soda
>fountains, bars, restaurants etc. Relatively harmless (ok, no
>environmental ozone damage anyway) readily available. I recently
>watched the installation of a CO2 generator, supposed to replace the
>tank of CO2 delivered on a regular basis. It works (according to
>the tech doing the install, by drawing CO2 out of the air, much the
>same way as a tree does. (I'm not a chemist; I know trees do that,
>but not how they do.) The tech said that the CO2 generator could be
>purchased or leased. That got me thinking.
>
>Propane/natural gas scares the crap out of me. Has since I blew the
>oven door off back in '67 and killed the kitchen table. I use it
>because I dislike electric even more. While the propane reduction
>system for electric kilns is safe (used properly), propane is still
>a highly flammable, explosive gas. . I'm always VERY mindful of it
>being on; it's called "keeping a wary eye..."
>
>And what does dry ice (frozen CO2) do when heated to cone 10, since
>it gassifies at room temp?
>
>Anyone?
>
>Wayne Seidl
>Key West FL US
>
>___________________________________________________________________________
___
>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.
>
>
>
>
____________________________________________________________________________
__
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.
Ivor and Olive Lewis on fri 12 nov 04
Dear Bruce,
My original post had a lot of stuff in it but I set the edit button
into activation and that was what you got.
Picked up a little gem yesterday. When natural iron ores are heated
above 600 =BA C in a environment rich in Carbon Monoxide the ore is
reduced, in its solid state, to Iron metal, better known as "Sponge
Iron". This is what the iron age folk played to make the first Iron
Artefacts.
By the way, and I'm sure you are aware of this, Blacksmiths would use
Silica Sand to flux the surface of Wrought Iron that was being forge
welded.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
----- Original Message -----
From: "Bruce Girrell"
To:
Sent: Friday, 12 November 2004 3:50
Subject: Re: Reduction environment and inert gases
> Ivor Lewis wrote:
>
> > By the way, I thought reduction in a clay body or of a glaze
> > ingredient was achieved by removing Oxygen from the metallic part
of
> > the compound using something for which Oxygen had a greater
affinity,
> > like Carbon monoxide, Hydrogen, a hydrocarbon or Carbon.
>
> Ivor,
>
> I didn't post anything to the list regarding reduction atmospheres
because I
> figured you'd jump all over that one, but you stated it rather
tentatively,
> so I'll state it more firmly:
>
> Reduction of metallic oxides (iron oxide, copper oxide, etc.) in our
glazes
> is not accomplished by the displacement of oxygen from the kiln
atmosphere.
> It is accomplished exactly as Ivor stated, by having a highly
reactive
> component of the atmosphere surrounding the objet d'art (whether in
a kiln
> or a reduction barrel) that wants to combine with oxygen more than
the metal
> is capable of holding on to the oxygen as an oxide. In effect, the
hot
> carbon, carbon monoxide, free hydrogen, etc. "steals" the oxygen
from the
> metallic oxide resulting in the production of CO, CO2, H2O, etc.
>
> The lack of oxygen in the kiln atmosphere is simply due to the fact
that the
> reactive components will happily eat up all of the oxygen in the air
that it
> can get to before doing the harder work of prying an oxygen free
from the
> metallic oxide.
>
> Any questions?
>
> Bruce "yes - you in the third row..." Girrell
>
>
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