P. Jaine Jacobs on thu 1 aug 96
Julie,
Here's the celadon recipe used successfully at the 92nd St Y in the gas kiln,
fired to ^10:
Sanders Celadon
44% Kona F4
18% Whiting
10% Kaolin
28% Flint
=100%
Then add 5% Barnard and 2% Bentonite
Hope it works for you,
Jaine in Cresskill, NJ, under a bright grey sky
ginny bivaletz on sat 13 nov 99
with my very limited understanding of glaze chemistry,
i think i understand a celedon glaze to be on that
gets it's blue or green color from the iron in it when
fired in a reduction atmosphere. am i correct to
assume that celadons are always glossy or is it
possible to have a mat celadon that would be durable
and food safe? thank you- ginny from washington state
=====
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Hank Murrow on mon 15 nov 99
>----------------------------Original message----------------------------
>i think i understand a celedon glaze to be on that
>gets it's blue or green color from the iron in it when
>fired in a reduction atmosphere. and is it
>possible to have a mat celadon that would be durable
>and food safe? thank you- ginny from washington state
Good Morning Ginny; Yes, most of the celadons fired in China during the
Sung period were not shiny. They don't like to be cooled too slowly. Often
very fine bubbles give this glaze a 'gongealed muttonfat' character which
is far more pleasing (to the old potters and to me) than the shiny surface
found on so many 'celadons' today. Incidently, these old ones were made
form an altered rhyolite(volcanic ash) which was called Petuntse, and the
glaze was made by adding 15-20% limestone and/or wood ash. The glaze fir
was marvelous when produced in this way, and the pots were translucent.
Nowadays, if you look for a source of hydrothermally altered rhyolite which
hasn't been contaminated by too much Ti and Fe; you can reproduce this ware
much more closely than by using the Grolleg or other kaolin bodies so
prevalent today. Good Luck, Hank in Eugwne
Dannon Rhudy on mon 15 nov 99
Celedon-type glazes are generally meant to be glossy, transparent to
transluscent. They were prized in China for their resemblance
in surface and color to jade, and their ability to "break" so beautifully over
carved surfaces. The color does come from the iron in reduction - you'll
note that celedon blues will sometimes look celery-green when
fired without sufficient reduction. But there are many colors of
celedon-type glazes, from heavy greens to soft blues to not-quite-white,
plus various ambers. You could look at Tichane's "Those Celedon
Blues" - a most helpful book.
Regards
Dannon Rhudy
potter@koyote.com
At 11:32 PM 11/13/1999 EST, you wrote:
>----------------------------Original message----------------------------
>with my very limited understanding of glaze chemistry,
>i think i understand a celedon glaze to be on that
>gets it's blue or green color from the iron in it when
>fired in a reduction atmosphere.
Paul Taylor on tue 16 nov 99
Dear Ginny
----------
Celedon glazes are made by reducing iron in a glaze. What is more
important is the amount of iron . As opposes to general glaze making
chemicals where it is unnecessary to be to fussy about amounts, differences
of 0.1 percent of iron can change a color. The other chemical that is
important for the color is titanium where 0.01 percent can make a
difference. I would be interested to know what other materials have a
dulling effect on the glaze ? When making the glaze you have to take the
titanium and the iron content of the glaze materials into account as these
are trace elements in most materials.
If you can manage to make a celedon that is both green/blue and matt
you are doing better than most of the potters since the sung dynasty.
We fool ourselves that we make celedons . As long as no one says that
these watery greens are pathetic we can carry on. We now also accept an
oxidized copper glaze to be a celedon.
Go to any museum look long at the glazes of the classical times and
cry.
Paul
>From: ginny bivaletz
>To: CLAYART@LSV.UKY.EDU
>Subject: celadon question
>Date: Sun, Nov 14, 1999, 4:32 am
>
>----------------------------Original message----------------------------
>with my very limited understanding of glaze chemistry,
>i think i understand a celedon glaze to be on that
>gets it's blue or green color from the iron in it when
>fired in a reduction atmosphere. am i correct to
>assume that celadons are always glossy or is it
>possible to have a mat celadon that would be durable
>and food safe? thank you- ginny from washington state
>
>
>=====
>
>__________________________________________________
>Do You Yahoo!?
>Bid and sell for free at http://auctions.yahoo.com
Jon Pettyjohn on tue 23 nov 99
Hi Hank,
I read your message about Chinese celadons with much interest.
I have been meaning to reply to you and ask you a few questions,
hope you don't mind.
I'm a potter here about an hour's drive south of Manila in
the Philippines. Lots of Chinese pottery was imported into
the country even before the Sung dynasty and up until the last
Ching dynasty. We're lucky to see many examples of the "mutton
fat" type glazes you mentioned, many of which were made in
the Ching te Chin kilns I think, and I have long been intrigued
by their sllky semi-transparent character.
I have heard of the legendary material "petuntse" but I have
never heard or read anywhere a real description. I would be most
interested to learn more, might you have an analysis?
Wouldn't volcanic ash contain too much iron to produce the
pale gray blue green colors. Was petuntse used in glazes
as well as the porcelain bodies? I had always understood that
petuntse was some kind of feldspathic or micaceous material,
some books say it also has plasticity.
Sorry to bombard you with questions, just got a little excited
by your mention of this mysterious stuff, I'd appreciate any
info or you could just aim me in the right direction by
giving me the book or article titles.
I have been fantasizing about getting hold of some of the real
stuff, I wonder if it's still available, we're so near China
here, but so hard to make contacts there.
One last question, you mentioned fast cooling as a factor in
the more opaque celadons, wouldn't the large wood kilns
that they say took even many days or a week to fire also cool
slowly?
thanks,
Jon Pettyjohn
Laguna, Philippines
jon@mozcom.com
> ----------------------------Original message----------------------------
> Good Morning Ginny; Yes, most of the celadons fired in China during the
> Sung period were not shiny. They don't like to be cooled too slowly. Often
> very fine bubbles give this glaze a 'gongealed muttonfat' character which
> is far more pleasing (to the old potters and to me) than the shiny surface
> found on so many 'celadons' today. Incidently, these old ones were made
> form an altered rhyolite(volcanic ash) which was called Petuntse, and the
> glaze was made by adding 15-20% limestone and/or wood ash. The glaze fir
> was marvelous when produced in this way, and the pots were translucent.
> Nowadays, if you look for a source of hydrothermally altered rhyolite which
> hasn't been contaminated by too much Ti and Fe; you can reproduce this ware
> much more closely than by using the Grolleg or other kaolin bodies so
> prevalent today. Good Luck, Hank in Eugwne
Hank Murrow on thu 25 nov 99
------------------
Good Day Jon=3B I am real glad you have had the luck to examine some of =
those
Jingdezhen wares. I include some remarks from David Stannard, who visited
these Petuntse mines for your information here:
=22I can't remember, either, responding to your query about
Jingdezhen quarry-- Did I reveal my ignorance on that one already?? I have
only speculation
following on the visit I made to the quarry entrance back in '82. It's very
near a small stream, =26 now goes down underground at a steep angle on =
rails, 7
km in an arc following down the dyke of altered Aplite(spar,qtz , =3C20=25 =
clay-
sized muscovite and =3C1=25 siderite, FeCo3, as I recall). Where it comes =
out to
the next valley is an area where they get kaolin to add to the pulverized P-
stone for a body(adding, also, I believe, some montmorillonite for =
plasticity).
>From the topography =40 mine-entrance I speculate, for myself, that the =
altered
Aplite exposed at creek bank in early days weathered out to a plastic,
Fe/Ti-free clay that, as they used it up in production, they followed down
underground =26 began having to mill it to release the clay-mica when =
passing
beyond the weathered zone. Pure speculation, but consistent with head/hands
pragmatic approach to 'follow your nose' potter's proclivities. Any scenario
more complicated I would discount as intellectual's daydream. As
clay-muscovite
fraction diminished they'd benefit by adding kaolin =26 =
'bentonite'(montmorillon-
itic) clays to keep it workable. The 60m dyke has been followed for 1000yrs,=
=26
I don't know whether they've picked-up on other regional sites, as that =
could
class as 'trade-secret'. Currently, they do add kaolin. Pamela Vandiver
will surely know more about that sort of historical shift, but if she
doesn't, I know a guy =40 Shanghai Inst. of Ceram. I could write to, if you
are really interested. Also, Tichane may have a good idea, tho I think he
pulled out of Ceramic interests a while back. I don''t know where the kao
ling name came from, tho seems I did read a ref. to hills named such.
Agin, I'm to careless a person to know those things.=22
David has been pioneering the prospecting of natural
porcelain-stones along the Pacific Rim, from California through Oregon and
Washington to Alaska, where he now resides. What he found was that the
Rhyolites(Fe/Ti-free volcanics) often contained large fractions of the
mineral Sericite, a plastic micaceous form leading to a useful natural
porcelain. A deposit many may be familiar with, is located in the Mohave
desert in CA, and is sold as Plastic Vitrox. Others have more or less
alkali content, depending upon subsequent hydrothermal alteration and
weathering processes. I mine and process such a Rhyolite which has had
about half the alkalis removed by alteration and some FE and Ti came along
with the steam and hot water to render this porcelain-stone not translucent
in C/10 fires, but beautiful shades of tan to mahogany brown with a
slightly self-glazed surface from remaining solubles=3B to irridescent black
in the anagama firing. It is called Calf Ridge Porcelain-stone.
Interestingly, if one adds 15-20=25 limestone to this body=3B the result is =
a
lovely greenish (due to the Ti) celadon which has a phenomenal fit to its
body, ringing like a bell.
This is the way those early Chinese potters did the gorgeous Sung
wares. They found clean extrusive (volcanic) rocks and ground them up for a
body, added lime to it for a glaze, and voil=E0, celadon=21 I have in my
collection several bowls made by David from Porcelain-stones gathered all
along the Pacific coast, which are self-glazed(added Limestone) celadons
all, and translucent. In fact, they are translucent at C/8, where they
exhibit that muttonfat quality you mention. If there's any significant Ti
present, they will not be translucent, and will be green not bluish in
color. So Jon, I suggest you make friends with a geologist or
well-driller(or both) to locate some hydrothermally altered and weathered
Rhyolite to try. Should be some in your islands due to their volcanic
nature. And if you fire your samples in a large multi-chambered kiln (as
the Sung potters did), stack them in the first two chambers where they will
cool relatively quickly while the subsequent chambers are still being
stoked. By the time the last chamber was finished abd the firebox was
sealed, those first two were nearly dark. Or just fire them in a little
(27cuft) kiln as I do. Wish I could show you some pics. Good Luck=21 Hank in
Eugene
=3E----------------------------Original message----------------------------
=3EHi Hank,
=3E
=3EI read your message about Chinese celadons with much interest.
=3EI have been meaning to reply to you and ask you a few questions,
=3Ehope you don't mind.
=3E
=3EI'm a potter here about an hour's drive south of Manila in
=3Ethe Philippines. Lots of Chinese pottery was imported into
=3Ethe country even before the Sung dynasty and up until the last
=3EChing dynasty. We're lucky to see many examples of the =22mutton
=3Efat=22 type glazes you mentioned, many of which were made in
=3Ethe Ching te Chin kilns I think, and I have long been intrigued
=3Eby their sllky semi-transparent character.
=3E
=3EI have heard of the legendary material =22petuntse=22 but I have
=3Enever heard or read anywhere a real description. I would be most
=3Einterested to learn more, might you have an analysis?
=3EWouldn't volcanic ash contain too much iron to produce the
=3Epale gray blue green colors. Was petuntse used in glazes
=3Eas well as the porcelain bodies? I had always understood that
=3Epetuntse was some kind of feldspathic or micaceous material,
=3Esome books say it also has plasticity.
=3E
=3ESorry to bombard you with questions, just got a little excited
=3Eby your mention of this mysterious stuff, I'd appreciate any
=3Einfo or you could just aim me in the right direction by
=3Egiving me the book or article titles.
=3E
=3EI have been fantasizing about getting hold of some of the real
=3Estuff, I wonder if it's still available, we're so near China
=3Ehere, but so hard to make contacts there.
=3E
=3EOne last question, you mentioned fast cooling as a factor in
=3Ethe more opaque celadons, wouldn't the large wood kilns
=3Ethat they say took even many days or a week to fire also cool
=3Eslowly?
=3E
=3Ethanks,
=3E
=3EJon Pettyjohn
=3ELaguna, Philippines
=3Ejon=40mozcom.com
=3E
=3E
=3E=3E ----------------------------Original =
message----------------------------
Genee on mon 20 nov 00
Hello - I got two recipes from the list several weeks
ago. One was titled "Good Grey Celadon" and the other
"Jade Celadon."
I was showing them to my clay teacher, and she wants
to know if the last ingredient, cobalt, in the Jade
Celadon, is cobalt carb, or a stain, or cobalt
sulphate, or what?
I think these were from Karen Sullivan, but not sure.
My teacher did say that they looked like excellent
recipes, and we are going to be mixing them for class.
So I do want to thank whoever posted the recipes and
get a clarification on the cobalt.
thanks from Jeannie Ramsey, in Santa Fe, in the snow.
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Marianne Lombardo on mon 20 nov 00
I would be very interested in knowing what the results of your testing are
like, if you don't mind. I've been thinking of mixing my own glazes, but so
far I don't sell anything, just make pottery for myself and friends. The
cost of firing is so expensive I've been afraid to get into glaze-making.
Marianne
----- Original Message -----
From: "Genee"
To:
Sent: Monday, November 20, 2000 1:05 PM
Subject: celadon question
> Hello - I got two recipes from the list several weeks
> ago. One was titled "Good Grey Celadon" and the other
> "Jade Celadon."
>
> I was showing them to my clay teacher, and she wants
> to know if the last ingredient, cobalt, in the Jade
> Celadon, is cobalt carb, or a stain, or cobalt
> sulphate, or what?
>
> I think these were from Karen Sullivan, but not sure.
> My teacher did say that they looked like excellent
> recipes, and we are going to be mixing them for class.
> So I do want to thank whoever posted the recipes and
> get a clarification on the cobalt.
>
> thanks from Jeannie Ramsey, in Santa Fe, in the snow.
>
> __________________________________________________
> Do You Yahoo!?
> Yahoo! Calendar - Get organized for the holidays!
> http://calendar.yahoo.com/
>
>
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