Wes Rolley on sun 24 apr 05
that got redder in oxidation refire.
Ron Roy said:
> Changes also happens in Shino glazes - more red after a bisue firing -
> again because there is more crystalization.
Ron,
I am confused by this statement. It seems to contradict what Hank
Murrow said about his shino glazes in a CLAYART item which I copied below=
:
> Pamela Vandiver and I did many scans with the SEM (scanning
> electron microscope) and the microprobe on my shino samples four
> years ago. We could find no evidence of a concentration of iron at
> the surface. The concentration remained remarkably equal throughout
> the entire glaze thickness. It IS very difficult to not believe that
> iron is concentrated, especially when you can see white just under
> that red color if you break one open. We believe that the iron that
> IS at the surface is available for re-oxidation during cooling or
> subsequent refiring.
The URL for Hank's full posting is:
http://lsv.ceramics.org/scripts/wa.exe?A2=3Dind0204B&L=3DCLAYART&P=3DR301=
42
So, is the result with shino the result of crystalization, or just the
re-oxidation of iron already on the surface? Hank's view makes more
sense to me. When examining one of Hank's shino bowls with a low
magnification ens, I can see no evidence of crystalization. What is the
evidence for crystalization as necessary for red color development?
Wes
--=20
"I find I have a great lot to learn =E2=80=93 or unlearn. I seem to know =
far too
much and this knowledge obscures the really significant facts, but I am
getting on." -- Charles Rennie Mackintosh
Wesley C. Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
http://www.refpub.com/
Lee Love on mon 25 apr 05
that got redder in oxidation refire.
Wes Rolley wrote:
Hank Wrote:
>>
>> that red color if you break one open. We believe that the iron that
>> IS at the surface is available for re-oxidation during cooling or
>> subsequent refiring.
>
>
> The URL for Hank's full posting is:
> http://lsv.ceramics.org/scripts/wa.exe?A2=ind0204B&L=CLAYART&P=R30142
>
> So, is the result with shino the result of crystalization, or just the
> re-oxidation of iron already on the surface?
Re-oxidation is the simple explanation. It makes sense from my
experiments. I put an unglazed Shigaraki pitcher that was already
fired to cone 14 in my 012 bisque and it got more red color from the
bisque.
When you fire a kiln of not only mixed temperatures, but also
having the ability to produce different atmospheres in terms of both
volatiles and oxidation/neutral/reduction, you are able to see a wide
range of different effects on the same work. This is very different
from the industrial "total control" perspective.
--
Lee in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
"Tolerance of irrational, outdated ideas in others, is not
`moral relativism.'
It is simply action motivated by the understanding,
that you cannot force your beliefs upon others."
-- Clyde Widdershins
Ron Roy on wed 27 apr 05
that got redder in oxidation refire.
Hi Wes,
So am I - I must have been nodding off.
The best expanation I have heard so far - is that a high alumina glaze
cannot hold iron in solution and it comes to the surface as the glaze
cools.
I have a cup that I cut in half and fired one half again in a bisque firing
to cone 04. More iron coming through on the refired half.
The point I was trying to make is - striking is all about giving things
time to happen - like slow cooling does to crystals.
I should have stuck to the copper and chrone tin reds to make my point.
Thanks - RR
>Ron Roy said:
>
>> Changes also happens in Shino glazes - more red after a bisue firing -
>> again because there is more crystalization.
>
>Ron,
>
>I am confused by this statement. It seems to contradict what Hank
>Murrow said about his shino glazes in a CLAYART item which I copied below:
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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