dannon rhudy on wed 27 jul 05
In order to get reduction in an electric kiln, you must
introduce some combustible material. You have to reduce
the amount of oxygen in the kiln. I would not do that
with a new kiln, were I you. You'll void your warranty,
and it could be hard on the elements, and maybe on the
controls.
The good news is, you don't need reduction for iron
red glazes. They are best in oxidation. They'll be much
more red (in reduction, the iron turns dark - slow cooling
will allow it to become red again). I've found that iron reds
also like slow cooling in oxidation, cone six or ten does not
matter. Try some tests in oxidation, choose a good recipe
and it will be a pleasure to use.
regards
Dannon Rhudy
> I just purchased an L&L DaVinci kiln. I'd like to test fire some of the
> Kaki glazes from John Britt's book (pages 73-74). Some of these are
fired on
> his "O2" firing schedule (pp 45), which is an oxidation firing up to cone
10,
> with a one hour soak in reduction, then back to oxidation for the
remainder of
> the firing. Can anyone tell me how to achieve that one hour cone 10
reduction
> soak in an electric kiln?
>
Brad Carter on wed 27 jul 05
I just purchased an L&L DaVinci kiln. I'd like to test fire some of the
Kaki glazes from John Britt's book (pages 73-74). Some of these are fired on
his "O2" firing schedule (pp 45), which is an oxidation firing up to cone 10,
with a one hour soak in reduction, then back to oxidation for the remainder of
the firing. Can anyone tell me how to achieve that one hour cone 10 reduction
soak in an electric kiln?
Brad Carter
Grass Valley, CA
Potter, Mark on wed 27 jul 05
Brad, I don't see your off line email address so I'm responding through
the server, so to the rest of you please forgive your having to read
this.=20
I'm not the electric kiln expert that many others on the list are. . .
(I'm partly answering this hoping someone out there knows something I
don't about this and it will satisfy my curiosity as well if I turn out
to be wrong . . here goes.
I believe it is close to impossible to get a one hour reduction at such
a high temperature in an electric kiln without injecting some kind of
flammable material, or gas other than oxygen into the fire (to steal the
oxygen) which is a kind of silly use of a good electric kiln as it tends
to destroy the elements of the kiln.
Electric kilns oxidize so far as I know, only that, and always have and
always will. I imagine there is a lot in the archives though about this
topic, and a lot of people have spent a lot of energy trying to figure
out ways to make electric kilns reduce. Some have succeeded I'm sure, in
part by doing things like piping in CO (Carbon monoxide which is deadly)
and other gasses into the kiln. But short of a high tech solution,
electric is not the way to go if you want to reduce your glazes.
Reduction occurs when burning occurs and there is a shortage of
available oxygen. An oxygen starved fire takes the oxygen out of the
oxides in your glazes, hence 'reducing' them from (and I'm putting this
very simply) iron oxide for example, to iron. In the case of iron there
are many different oxides, and reduction can happen partially leaving a
mix of different colored iron oxides in the final glaze. This is what
makes iron based glazes so exciting to work with. But please out there,
correct me if I'm wrong, you can't do this in an electric kiln, not
without making it a fuel burner of some sort, or piping in carbon
monoxide or some other gas to replace the oxygen.
I'd suggest firing those khaki glazes in a wood or gas kiln. Look around
you someone has one I'm sure in your area.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Brad Carter
Sent: Wednesday, July 27, 2005 1:42 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: cone 10 reduction soak in electric kilns
I just purchased an L&L DaVinci kiln. I'd like to test fire some of
the
Kaki glazes from John Britt's book (pages 73-74). Some of these are
fired on
his "O2" firing schedule (pp 45), which is an oxidation firing up to
cone 10,
with a one hour soak in reduction, then back to oxidation for the
remainder of
the firing. Can anyone tell me how to achieve that one hour cone 10
reduction
soak in an electric kiln?
Brad Carter
Grass Valley, CA
________________________________________________________________________
______
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.
Ken Chin-Purcell on wed 27 jul 05
> I'd like to test fire some of the
> Kaki glazes from John Britt's book (pages 73-74).
I'd suggest firing those khaki glazes in a wood or gas kiln. Look around
> you someone has one I'm sure in your area.
Another idea: fire a load in your new kiln sans reduction, and see what you=
=20
get. That hour of reduction may be just to get the iron to flux - if the=20
results looks underfired you may want to try adding some frit, like 3134, t=
o=20
lower the cone a notch or two; each cone number is a tenth of a mole of=20
boron. As Mel has shown, there are lots of decent oxidized iron glazes. I=
=20
only fire to cone 9, but my workhorse glaze is an oxidized iron saturate.
Let us know how it turns out! I'm too busy now to be doing a lot of glaze=
=20
tests, but I'm already making my plans for after Christmas...
-- Ken Chin-Purcell
Bungalow Pottery
| |
|
