Chris Groat on fri 30 mar 07
I tried post-fire reduction this week for the first time. I've just been
taking all of my random test pieces and throwing them in there to see what
will happen. Generally, any test glaze that I like I leave in vinegar for
three days. I found that the glazes left in vinegar are very easily
reduced. Take a look at this test piece where just the bottom half was
submerged in vinegar. It even works for glazes that pass the vinegar test
flawlessly. Is it common practice to leave a piece in vinegar or anything
else before reducing? The red color on this piece is beautiful! Can anyone
explain these strange results? Is the acidic vinegar pulling free copper
to the surface so that it can be more easily reduced?
http://tinyurl.com/yvbyss
Chris
Marcia Selsor on fri 30 mar 07
Chris,
This is interesting. But I don't follow how you are post-fire
reducing. Are you refiring after the vinegar soak?
Marcia
Marcia Selsor
http://marciaselsor.com
On Mar 30, 2007, at 1:42 AM, Chris Groat wrote:
> I tried post-fire reduction this week for the first time. I've just
> been
> taking all of my random test pieces and throwing them in there to
> see what
> will happen. Generally, any test glaze that I like I leave in
> vinegar for
> three days. I found that the glazes left in vinegar are very easily
> reduced. Take a look at this test piece where just the bottom half was
> submerged in vinegar. It even works for glazes that pass the
> vinegar test
> flawlessly. Is it common practice to leave a piece in vinegar or
> anything
> else before reducing? The red color on this piece is beautiful! Can
> anyone
> explain these strange results? Is the acidic vinegar pulling free
> copper
> to the surface so that it can be more easily reduced?
>
> http://tinyurl.com/yvbyss
>
> Chris
Marcia Selsor
http://marciaselsor.com
Chris Trabka on fri 30 mar 07
Chris,
John Britt explains post firing reduction quite well in his book
"The Complete Guide to High Fired Glazes". I would strongly doubt that the
vinegar would have any effects on the reduction, but I will let the experts
chime in here. In post firing reduction, the color is a surface color; much
like a luster.
Chris
Dannon Rhudy on fri 30 mar 07
One really can't tell a lot just by looking at an
image. However - how much copper was in
the glaze to begin with? It looks like a lot.
If the vinegar leached some of the copper from
the piece, that might have an effect on the
results. Most copper red glazes have less than
1/2 percent copper in them; more copper often
means less red. What temp were the pieces fired
to? What do you mean by "post firing reduction"?
More information will be helpful.
regards
Dannon Rhudy
----- Original Message -----
From: "Chris Groat"
To:
Sent: Friday, March 30, 2007 1:42 AM
Subject: Copper Reduction- Strange Results
> I tried post-fire reduction this week for the first time. I've just been
> taking all of my random test pieces and throwing them in there to see what
> will happen. Generally, any test glaze that I like I leave in vinegar for
> three days. I found that the glazes left in vinegar are very easily
> reduced. Take a look at this test piece where just the bottom half was
> submerged in vinegar. It even works for glazes that pass the vinegar test
> flawlessly. Is it common practice to leave a piece in vinegar or anything
> else before reducing? The red color on this piece is beautiful! Can anyone
> explain these strange results? Is the acidic vinegar pulling free copper
> to the surface so that it can be more easily reduced?
>
> http://tinyurl.com/yvbyss
>
> Chris
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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melpots@pclink.com.
>
Chris Groat on fri 30 mar 07
I dipped the piece in vinegar prior to firing. I only dipped it in vinegar
to see if the glaze was stable. I certainly didn't expect these results.
With every piece I've tested, the half that was left in vinegar is much
more easily reduced. I'm using copper carb and it ranges from 1-3%. I'm
using a kiln that I made out of a trash-can. Firing to 1470F, and reducing
down to about 1200F.
I guess your posts answer one of my questions. Apparently it is not common
practice to soak a piece in vinegar before doing a post-fire reduction.
But seriously, there has to be some kind of similar surface prep, right?
Chris
Veena Raghavan on fri 30 mar 07
Another questions piggybacking on Marcia's: how are you firing the second
time around? Thanks.
Veena
In a message dated 3/30/2007 9:20:02 AM Eastern Daylight Time, selsor@IMT.NET
writes:
>
> Chris,
> This is interesting. But I don't follow how you are post-fire
> reducing. Are you refiring after the vinegar soak?
> Marcia
> Marcia Selsor
VeenaRaghavan@cs.com
vanessa nelson on mon 9 apr 07
That is a very beautiful result. Do you mind if i pass it on to my
professor?
>From: Chris Groat
>Reply-To: Clayart
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: [CLAYART] Copper Reduction- Strange Results
>Date: Fri, 30 Mar 2007 01:42:23 -0500
>
>I tried post-fire reduction this week for the first time. I've just been
>taking all of my random test pieces and throwing them in there to see what
>will happen. Generally, any test glaze that I like I leave in vinegar for
>three days. I found that the glazes left in vinegar are very easily
>reduced. Take a look at this test piece where just the bottom half was
>submerged in vinegar. It even works for glazes that pass the vinegar test
>flawlessly. Is it common practice to leave a piece in vinegar or anything
>else before reducing? The red color on this piece is beautiful! Can anyone
>explain these strange results? Is the acidic vinegar pulling free copper
>to the surface so that it can be more easily reduced?
>
>http://tinyurl.com/yvbyss
>
>Chris
>
>______________________________________________________________________________
>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.
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