Fredrick Paget on sat 15 nov 03
>Hi Again,
>
>I was telling my dad about my need for high temp wire & he suggested
>tungsten. i looked up the melting point & it's very high...around
>6000 f. Then it
>occurred to me that maybe this Kemper High Temp Wire that I bought is in fact
>tungsten. Does anyone know? If it's not, has anyone tried tungsten in a
>raku kiln?
>Simona
>
>_
Tungsten metal readily oxidizes completely at red heat and you will
just have a pile of tungsten oxide. Ever turned on a broken light
bulb that has air in it but the filament was intact? Remember how it
smoked up as the tungsten oxidized?
The Kemper wire is probably a Kanthal alloy of some sort, a nickle
chromium based alloy.
Fred
--
From Fred Paget, Marin County, California, USA
fredrick@well.com
Simona Drentea on sat 15 nov 03
Hi Again,
I was telling my dad about my need for high temp wire & he suggested
tungsten. i looked up the melting point & it's very high...around 6000 f. Then it
occurred to me that maybe this Kemper High Temp Wire that I bought is in fact
tungsten. Does anyone know? If it's not, has anyone tried tungsten in a
raku kiln? I'm in a class situation, so I don't want to use anything that could
harm the kiln or anyone elses's pieces.
Thanks,
Simona
Tony Ferguson on sat 15 nov 03
Kempler does not use tungsten unless they have something out very new.
Tungsten is expensive!!!!!!!!!! There is a company that makes some kicken
tungsten tools and they are $40 and up. Coleman says once you go tungsten
you never go back! I'm still saving my pennies for one of those babies.
Just use the high temp wire in the lower gages (thicker) and you will be
fine for odd posting, or separating sculpture, pots, etc. Use the medium
(from bulk) or the Kempler High Temp Wire pre-packed (more expensive). I've
used the Kemplar and various sized bulk high temp wire for my raku kilns and
they all work great. You would be wasting your money using tungsten in the
raku kiln.
Thank you.
Tony Ferguson
On Lake Superior, where the sky meets the Lake
Custom & Manufactured Kiln Design
Stoneware, Porcelain, Raku and more
by Coleman, Ferguson, Winchester...
http://www.aquariusartgallery.com
218-727-6339
315 N. Lake Ave
Apt 312
Duluth, MN 55806
----- Original Message -----
From: "Simona Drentea"
To:
Sent: Saturday, November 15, 2003 1:44 PM
Subject: tungsten wire - high temp wire
> Hi Again,
>
> I was telling my dad about my need for high temp wire & he suggested
> tungsten. i looked up the melting point & it's very high...around 6000 f.
Then it
> occurred to me that maybe this Kemper High Temp Wire that I bought is in
fact
> tungsten. Does anyone know? If it's not, has anyone tried tungsten in a
> raku kiln? I'm in a class situation, so I don't want to use anything that
could
> harm the kiln or anyone elses's pieces.
>
> Thanks,
> Simona
>
>
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iandol on sun 16 nov 03
Dear Simona Drentea,
As I recall, Tungsten metal is extremely brittle. It also has a very =
high density. It is also most expensive. Not the sort of thing you might =
find in a pottery classroom. Now Tungsten Carbide Tools for trimming.... =
now that's a real ball game. Never wear out,=20
Best regards,
Ivor Lewis. Redhill, South Australia=20
=20
masta@UMICH.EDU on sun 16 nov 03
Tungsten does indeed have a high melting point, but as with many
other metals that is not the issue when using it in your kiln;
it is *oxidation* that is the problem. And oxidation of tungsten
is extreme and fairly dramatic even at earthenware temperatures.
(Recall that tungsten is used in light bulb filaments, which burn
out immediately if the envelope seal fails.)
Also, tungsten is incredibly brittle and hard to draw into wire
in the first place. I understand they usually make it by
mashing together several smaller-diameter strands, which
you can see when you try to cut the wire - it cracks along
the original strand boundaries.
I tried to use some tungsten wire (free from a friend) to make a
bunch of little stilts for glazing buttons. Yeah, I knew about
light bulbs, but I figured that those have to get white hot,
and these were only going to ^2. I pushed short stubs of
wire into a clay pad to make the stilts.
After the firing, the tungsten was found to have burst open
along the original strand boundaries into little "flowers",
pale green in color. These were very fragile; many had
already broken and dropped their loads. Lots of buttons
had crashed into each other and glaze-welded together... argh!
However, there was one interesting result which I have yet
to pursue much farther. Evidently something about the oxidation
of the tungsten, maybe in combination with something in the
clay pad or the glaze on the button it was supporting, caused
a corrosive "wind" to emanate from the point of each stilt.
The glaze on the underside of each button had deeply etched
grooves that streamed away from the point and wrapped up
and around the rim and partly onto the top surface of the
button. It would be a really nice effect if such a star
could be induced on the face of a piece. I did try one
really simple test, just sticking a couple stubs of wire into
test bars before applying the glaze and also setting into
the glaze, but without any success. I do intend to get
back to this eventually. I'll report results here.
Robert Masta
dqatech@daqarta.com
D A Q A R T A
Data AcQuisition And Real-Time Analysis
Shareware from Interstellar Research
www.daqarta.com
Bruce Girrell on mon 17 nov 03
> I was telling my dad about my need for high temp wire & he suggested
> tungsten.
What you want is called Nichrome wire. It is the stuff that elements in
electric kilns are made from. Ward Burner has it and I'm sure that you can
get it other places.
Bruce Girrell
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