Arnolds Home Improvements on tue 1 oct 02
Just out of curiosity why can't the same effects of copper reds that are
achieved in a gas kiln be done in a raku firing???
Gene Arnold
mudduck@advi.net
Philip Poburka on tue 1 oct 02
Raku ain't near as hot...Coppers as to be 'red' as in a
reduction High Fire, I believe need to be High Fired...
My impression anyway...
Phil
Las Vegas
----- Original Message -----
From: "Arnolds Home Improvements"
To:
Sent: Tuesday, October 01, 2002 2:18 PM
Subject: red raku different ??
Just out of curiosity why can't the same effects of copper
reds that are
achieved in a gas kiln be done in a raku firing???
Gene Arnold
mudduck@advi.net
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Tommy Humphries on tue 1 oct 02
it can, I use a glaze called "lithium blue" that under heavy reduction in
the kiln is a nice bright red when finished. I don't have the recipe handy,
and can't remember if it was listed in S. Branfmans book, or Pipenberg's.
under "normal" raku conditions it is a great turquoise with good copper
flashing.
Tommy
----- Original Message -----
From: "Arnolds Home Improvements"
To:
Sent: Tuesday, October 01, 2002 4:18 PM
Subject: red raku different ??
> Just out of curiosity why can't the same effects of copper reds that are
> achieved in a gas kiln be done in a raku firing???
>
>
>
> Gene Arnold
> mudduck@advi.net
>
>
____________________________________________________________________________
__
> 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.
>
Brooks Ratledge on tue 1 oct 02
I have fired copper red, not luster in a raku firing. I used a raku glaze
with a small amount of copper (typical for a reduction copper red). When
the glaze was melted, I didn't put the pots in post firing reduction but let
them cool in the air. It was interesting to watch the reds develop as the
pots cooled. Patricia Harden
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-----Original Message-----
From: Arnolds Home Improvements
To: CLAYART@LSV.CERAMICS.ORG
Date: Tuesday, October 01, 2002 8:50 PM
Subject: red raku different ??
>Just out of curiosity why can't the same effects of copper reds that are
>achieved in a gas kiln be done in a raku firing???
>
>
>
>Gene Arnold
>mudduck@advi.net
>
>___________________________________________________________________________
___
>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.
Bruce Girrell on wed 2 oct 02
Gene Arnold wrote:
> Just out of curiosity why can't the same effects of copper reds that are
> achieved in a gas kiln be done in a raku firing???
Brooks Ratledge responded:
> I have fired copper red, not luster in a raku firing...
> I didn't put the pots in post firing reduction but let them cool in the
air.
> It was interesting to watch the reds develop as the pots cooled.
and Dannon Rhudy wrote:
> I have fired raku glazes for quite some time that develop copper red.
And I will also say that true copper reds are definitely possible at raku
temperatures. The glazes that I used were of high copper content, i.e.,
normal copper content for a raku glaze. Microscopic examination of the
results showed much in the way of visible copper crystals, but also a
transparent ruby color. The copper crystals were more evident in the more
oxblood regions and the copper reds seemed to be more along interfaces,
e.g., near edges in the glaze and near bubbles. This would indicate to me
that the copper content of my glaze was too high and is consistent with the
formulation of copper red glazes which use a very low copper content.
As Brooks noted, these reds do not develop during firing; they develop
during the cooling period and it is, indeed, fascinating to watch them
develop before your eyes. And as Dannon said later in her comments, I found
the effect difficult to control. There is certainly plenty of room out there
for experimentation if someone is interested in putting in the hours.
Bruce Girrell
who seems to be lacking a snappy internym today
John Christie on wed 2 oct 02
A good copper red glaze for raku can be made from:
alkaline borax frit : 85
china clay : 10
bentonite : 2
tin oxide : 5
copper carbonate : 1
iron oxide : 1.5
The tin and iron oxides seem to aid reduction. The glaze should be =
cooled a little in a reducing atmosphere for the best reds. Depending on =
your frit, 100 deg. C. should be enough to melt the glaze, cooling in =
reduction to 850 or so. Subsequent reduction in sawdust etc. will just =
result in a nasty metallic copper finish so cool on a piece of wood to =
give that nice blackened foot with a hint of lustre at the base of the =
glaze.
I certainly would not suggest adding five percent depleted uranium oxide =
to the glaze - this would be very foolish!
John Christie
www.blackhillspottery.co.uk
Moray, Scotland
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