Gary Ferguson on sat 5 apr 03
Resend
----- Original Message -----
> Steven:
>
> I'm not surprised at the results you obtained, especially if you are
> reducing heavily. (i.e. moving the piece from the kiln to the reduction
> chamber quickly and using lots of combustible material). Also you note the
> plates are heavy. Thicker clay will cool slower and allow easier
reduction
> as well. The Copper in the glaze is going to create the copper colors if
it
> is highly reduced. If you reduced a little less, or burped the reduction
> container a bit you would probably end up with more blues and greens.
>
> Gary Ferguson
> Raku Clay Artist
> Nampa, ID 83687
> Visit my site at http://www.garyrferguson.com
> Subscribe to Just Raku Newsletter at http://www.JustRaku.com
>
>
> ----- Original Message -----
> From: "Steven D. Lee"
> To:
> Sent: Friday, April 04, 2003 7:01 AM
> Subject: Perhaps and Unanswerable question about Raku Glaze
>
>
> > I finally learned what was in the glaze I had used for my 1st raku
> > firing and calculated approximately the additions in it plus the
> > additions I made. Here it is:
> >
> > Gerstley Borate 75%
> > F4 Feldspar 18%
> > Zircopax 7%
> >
> > Add:
> >
> > Cobalt Carbonate 4%
> > Black CU Oxide 4%
> >
> >
> > With this in mind, I talked with another potter who has done some
> > Raku and he said that he couldn't believe I got the shiny metalic
> > copper surface that I did. He said that only with Stanous Chloride
> > fuming could he or other Rakuists he knew get that surface.
> >
> > http://www.sdpottery.com/Ceramic_Misc/New_Arrivals.htm
> >
> > Thanks!!!!
> >
> > ***************************************************
> > Steven D. Lee
> > SD Pottery - The Little Texas Potter
> > http:\\www.sdpottery.com
> > millenial_age@yahoo.com
> > 14341 FM 112
> > Thrall, TX 76578
> > 512-898-5195
> > ***************************************************
> >
> >
>
____________________________________________________________________________
> __
> > 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.
>
Craig Dunn Clark on sun 6 apr 03
Steven, just to add to what Gary has said. I am also not surprised by
your results. I don't know who is advising you but be skeptical of what they
are saying if they think that only Stannous Chloride will give you the
results that you describe. I regularly am able to get a shiny copper penny
colored surface if that is what I'm after. The glaze that I'm using is quite
similar to yours except that I do not use any cobalt carb.
Remember, it is the copper oxide that is giving you the color. It is the
ratio of silica to alumina in the glaze and the temperature to which you
fire that are resulting in the quality of surface (glossy/matt, etc.) When
copper is reduced it goes to the "copper" color. When it is oxidized it goes
green.
If you consistenly want the coppery look just get the pots into nice
tight reduction containers quickly. No more than a few seconds before you
shut your cans. Don't re-open...aka "burp" ....them if you don't want green
showing up. Especially if the pieces are heavy.
The residual heat in the heavier peices will enable you to be a little
more relaxed with the speed with which you get the pieces into reduction,
but, because of that residual heat, the glaze will cool more slowly and will
be subject to re-oxidation for a longer period of time. Hence the need for a
nice tight can or container.
If you really want the skinny on all of this go out to the digital fire
websight and read the articles by Tom Buck. He knows quite well of what he
speaks. Additionally, go into the archives and clayart and you will find the
writings of Marcia Selsor and Steve Branfman of the subject of raku....they
are world class experts.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
----- Original Message -----
From: "Gary Ferguson"
To:
Sent: Saturday, April 05, 2003 10:19 PM
Subject: Fw: Perhaps and Unanswerable question about Raku Glaze
> Resend
> ----- Original Message -----
> > Steven:
> >
> > I'm not surprised at the results you obtained, especially if you are
> > reducing heavily. (i.e. moving the piece from the kiln to the reduction
> > chamber quickly and using lots of combustible material). Also you note
the
> > plates are heavy. Thicker clay will cool slower and allow easier
> reduction
> > as well. The Copper in the glaze is going to create the copper colors
if
> it
> > is highly reduced. If you reduced a little less, or burped the
reduction
> > container a bit you would probably end up with more blues and greens.
> >
> > Gary Ferguson
> > Raku Clay Artist
> > Nampa, ID 83687
> > Visit my site at http://www.garyrferguson.com
> > Subscribe to Just Raku Newsletter at http://www.JustRaku.com
> >
> >
> > ----- Original Message -----
> > From: "Steven D. Lee"
> > To:
> > Sent: Friday, April 04, 2003 7:01 AM
> > Subject: Perhaps and Unanswerable question about Raku Glaze
> >
> >
> > > I finally learned what was in the glaze I had used for my 1st raku
> > > firing and calculated approximately the additions in it plus the
> > > additions I made. Here it is:
> > >
> > > Gerstley Borate 75%
> > > F4 Feldspar 18%
> > > Zircopax 7%
> > >
> > > Add:
> > >
> > > Cobalt Carbonate 4%
> > > Black CU Oxide 4%
> > >
> > >
> > > With this in mind, I talked with another potter who has done some
> > > Raku and he said that he couldn't believe I got the shiny metalic
> > > copper surface that I did. He said that only with Stanous Chloride
> > > fuming could he or other Rakuists he knew get that surface.
> > >
> > > http://www.sdpottery.com/Ceramic_Misc/New_Arrivals.htm
> > >
> > > Thanks!!!!
> > >
> > > ***************************************************
> > > Steven D. Lee
> > > SD Pottery - The Little Texas Potter
> > > http:\\www.sdpottery.com
> > > millenial_age@yahoo.com
> > > 14341 FM 112
> > > Thrall, TX 76578
> > > 512-898-5195
> > > ***************************************************
> > >
> > >
> >
>
____________________________________________________________________________
> > __
> > > 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.
> >
>
>
____________________________________________________________________________
__
> 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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