Derrick Pottery - owner - Wesley Derrick on tue 17 jun 03
I was emailed this link
http://crystalline-ceramics.info/reduction.html
and it is a very interesting setup...I do have a few questions though....
Has anyone else tried this technique? If so, please let me know.
wesley
Fara Shimbo on wed 18 jun 03
Hi, Everyone,
Yeah, the link is mine. I'd like to offer a few comments about it.
This technique is a modification of a technique found in almost
all crystalline ceramics books, so while the link is on my site
I can't take credit for the technique. Usually vegetable oil is used.
Our own Jon Singer suggested using alcohol. Works a treat!
The problem with it, apart from it voids your warrantee, is
that if the kiln isn't completely closed before you add the
alcohol, it spits fire like a wet cat. Because of this, I found
I was unable to get insurance to cover the August workshops
if I taught this technique. So I thought about it long and
hard and decided I would buy my gas kiln to teach the reduction
techniques in since a gas kiln is the "usual" way reduction is
done.
Well, the electric kiln reduction -might- spit fire, but the
gas kiln -always- does, in flames half a meter tall out the
top port and licks of flame out the spyholes. (I named the
kiln Norbert.) But getting insurance for that was no problem.
Why it was no problem was never adequately explained. But not
only was I advised not to teach the alcohol technique at the workshop,
but to take it off the website and out of the book, partly because
it was a "dangerous" thing to do and partly because "The worse the
economy, the more litigious people become."
That said, I did some experiments to find out if I could get
the same results in the gas kiln as I did with the alcohol and
the answer turns out to be no. Copper works fine. Oil-spot
works fine. Silver ... after three tries I have not been able
to get a hint of reduction on the silver in the gas kiln.
I know silver fumes, and I wonder if maybe the silver is just
carried out of the kiln in the updraft during firing?
Oh well, that's my morning rant.
(P.S., I don't get spam from Clayart -- I get spam from people
harvesting my address off my websites. So I mangled my address
and the spam is much less.)
Hang in there, everyone,
Fa
--
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Fara Shimbo, Master Crystalliere, Certified Public Nuisance
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Shimbo Pottery, P.O. Box 41, Hygiene, Colorado 80533 USA
720.272.0442 7AM to 2 PM, Mountain Time
www.crystalline-ceramics.info www.shimbopottery.com
Silly Science Fiction: http://klysadel.net
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Fredrick Paget on wed 18 jun 03
I can't see how using carbon monoxide would be considered less
dangerous than alcohol.
First I don't think you can get it unless you generate it your self.
It is very poisonous . I had personal experience with it. I lost an
eye as a result of an accident caused by a fall after carbon monoxide
poisoning.
A better possibility is hydrogen. It is a powerful reducing agent in
a kiln and it is not poisonous..
It is used in industry for reduction firing. We had a muffle furnace
at Sylvania that had a hydrogen atmosphere and it was used to reduce
the oxide coating on moly wire before it was built into light bulbs
of rather exotic types.
The furnace has to be designed to be safe with the hydrogen inside.
Ours was a long square refractory tube open at the ends, if it blew
it would vent out the ends, There were top-hinged doors on it that
had little adjacent pilot fires so that when you opened the door the
air would burn before it got inside the long tube. Pure hydrogen
inside won't burn if there is no air in it.
A mixture of hydrogen and air at the right proportion will explode .
So will a mixture with air and just about any fuel gas.
I have read somewhere that a mixture of 5 percent hydrogen and 95
percent nitrogen will not explode. I have been thinking that filling
the kiln with such a mixture from a bottle of compressed gas might be
a way to go. You would want to verify this on a very small scale
first as you would need to see if it would blow up.
I once asked the local supplier of mixed gasses for welding if they
could supply such a mix and they could.
It would probably reduce the oxide coating on the elements too so
they would be like new after each firing. You would have to do an
oxidation firing between each use.
Fred
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From Fred Paget, Marin County, California, USA
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