dannon rhudy on sat 24 sep 05
I'm not absolutely sure that I understand all
of your question(s). However, Oribe glazes
are notorious for turning "an awful mauve
color". Reasons? If your clay body is
not really white, the clay shows through (brownish).
Oribe is a nearly transparent glaze. When it
turns pink/red in reduction, and the clay shows
through, it is muddy and unattractive. This happens
when the glaze is a bit thin and reduction is less
than optimal. Oribe glazes in my experience turn
red fairly easily. So - make sure it is thick enough
(though some run, so watch the foot). Also, if there
is too much carbon in the atmosphere, then oribe
glazes, like other carbon traps, turn a liverish brownish
pinkish disgusting sort of color. Oribe can be
beautiful, especially when some turns red and some
stays green - but watch application and reduction.
AND your claybody.
regards
Dannon Rhudy p.s. copper is volatile, but does not
necessarily "burn off" at high temps. Depends on the
glaze, the application, etc.
Subject: Reduction Colors
> Jeri attended a workshop and one of the glazes that was used was called
> Oribe, fired to ^10R.
>
> OM 4 14.25
> Custer spar 30.54
> Whiting 20.48
> Silica 34.73
> copper carb 8.01
>
> The pots she brought home were a shiny bluish green.
>
> The pots we are getting out are an awful mauve color.
Paul Lewing on wed 28 sep 05
on 9/28/05 6:27 PM, Dave Finkelnburg at idahopottery@YAHOO.COM wrote:
> You have your problem figured out. The glaze you posted is a fairly classic
> high-calcium Oribe. If you are getting a purple or reddish cast to the glaze
> it is due to reduction. You will get more green in oxidation, even periodic
> oxidation. In my experience with this sort of glaze, you won't get the copper
> burning out in a "normal" firing schedule. It will be trapped down in the
> glass. However, you do need fairly mild reduction to even oxidation at
> critical times to prevent forming a form of a copper red. To get a really red
> glaze you would typically use about 5% tin and very little (say 0.25%) copper
> carbonate in the glaze, combined with consistent reduction. The tin in the
> spod glaze may be why you get maroon. You are just on the reduction side a
> little too much right now.
Frank, I pasted Dace's reply here so it could be read again, as it very
succinctly sums it up. You are getting red- or at least as red as you can.
The one thing I'd add to Dave's comments is that, in addition to the Sn and
the Cu and the reduction, to get a real copper red, you also have to have
high silica and low alumina. Neither of the two glazes you mention fit that
bill, nor would any combination of the two.
Paul Lewing, Seattle
Off to Northern Clay Center in Minneapolis this weekend. Stop in for the
slide show on Sunday afternoon, or there's probably still space in the
workshop. "You, too can LEARN...........TO....PAINT!"
Hank Murrow on wed 28 sep 05
Dear Frank;
You are getting reduction enough to turn the copper mauve......too much
copper in this recipe for red. Try washing the mauve surface with weak
acid to clean it. These glazes were originally fired in oxidation
primarily, so you should too if you want oribe color.
Cheers, Hank
www.murrow.biz/hank
On Sep 28, 2005, at 3:41 PM, JANFAM wrote:
> Jeri attended a workshop and one of the glazes that was used was called
> Oribe, fired to ^10R.
>
> OM 4 14.25
> Custer spar 30.54
> Whiting 20.48
> Silica 34.73
> copper carb 8.01
>
> The pots she brought home were a shiny bluish green.
>
> The pots we are getting out are an awful mauve color.
>
> From what I can glean from the books we have, copper is highly volatile
> and burns off at ^10. Where this glaze is overlapped by a Spodumene
> glaze
>
> Custer 28.04
> EPK 24.30
> Dolomite 20.56
> Spodumenr 18.69
> Whiting 1.87
> Bentonite .93
> Tin Oxide 5.6
>
>
> it is a nice maroon color.
>
> I think that this means the kiln is in reduction, but where is the
> green
> of Oribe?? Should'nt the copper produce red and not green in
> reduction??
JANFAM on wed 28 sep 05
Jeri attended a workshop and one of the glazes that was used was called
Oribe, fired to ^10R.
OM 4 14.25
Custer spar 30.54
Whiting 20.48
Silica 34.73
copper carb 8.01
The pots she brought home were a shiny bluish green.
The pots we are getting out are an awful mauve color.
From what I can glean from the books we have, copper is highly volatile
and burns off at ^10. Where this glaze is overlapped by a Spodumene glaze
Custer 28.04
EPK 24.30
Dolomite 20.56
Spodumenr 18.69
Whiting 1.87
Bentonite .93
Tin Oxide 5.6
it is a nice maroon color.
I think that this means the kiln is in reduction, but where is the green
of Oribe?? Should'nt the copper produce red and not green in reduction??
Frank
Dave Finkelnburg on wed 28 sep 05
Frank,
You have your problem figured out. The glaze you posted is a fairly classic high-calcium Oribe. If you are getting a purple or reddish cast to the glaze it is due to reduction. You will get more green in oxidation, even periodic oxidation. In my experience with this sort of glaze, you won't get the copper burning out in a "normal" firing schedule. It will be trapped down in the glass. However, you do need fairly mild reduction to even oxidation at critical times to prevent forming a form of a copper red. To get a really red glaze you would typically use about 5% tin and very little (say 0.25%) copper carbonate in the glaze, combined with consistent reduction. The tin in the spod glaze may be why you get maroon. You are just on the reduction side a little too much right now.
Good potting!
Dave Finkelnburg
JANFAM wrote:
Jeri attended a workshop and one of the glazes that was used was called
Oribe, fired to ^10R.
OM 4 14.25
Custer spar 30.54
Whiting 20.48
Silica 34.73
copper carb 8.01
The pots she brought home were a shiny bluish green.
The pots we are getting out are an awful mauve color.
From what I can glean from the books we have, copper is highly volatile
and burns off at ^10. Where this glaze is overlapped by a Spodumene glaze
Custer 28.04
EPK 24.30
Dolomite 20.56
Spodumenr 18.69
Whiting 1.87
Bentonite .93
Tin Oxide 5.6
it is a nice maroon color.
I think that this means the kiln is in reduction, but where is the green
of Oribe?? Should'nt the copper produce red and not green in reduction??
Frank
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Rikki Gill on wed 28 sep 05
Hi Jeri
I use Oribe glaze all the time, and on most of my pots. I fire to cone 11.
I never really have problems with it. Sometimes where thin it turns copper
red, but I like that effect. If you would like to see the oribe color that
I get, you can look at my website
www.rikkigillceramics.com. You might have a formula problem.
In general I find this an easy glaze. It loves heavy reduction and fires
well with Shino.
Good luck, Rikki Gill
----- Original Message -----
From: "JANFAM"
To:
Sent: Wednesday, September 28, 2005 3:41 PM
Subject: Reduction Colors
> Jeri attended a workshop and one of the glazes that was used was called
> Oribe, fired to ^10R.
>
> OM 4 14.25
> Custer spar 30.54
> Whiting 20.48
> Silica 34.73
> copper carb 8.01
>
> The pots she brought home were a shiny bluish green.
>
> The pots we are getting out are an awful mauve color.
>
> From what I can glean from the books we have, copper is highly volatile
> and burns off at ^10. Where this glaze is overlapped by a Spodumene glaze
>
> Custer 28.04
> EPK 24.30
> Dolomite 20.56
> Spodumenr 18.69
> Whiting 1.87
> Bentonite .93
> Tin Oxide 5.6
>
>
> it is a nice maroon color.
>
> I think that this means the kiln is in reduction, but where is the green
> of Oribe?? Should'nt the copper produce red and not green in reduction??
>
>
> Frank
>
>
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