Vince Pitelka on wed 5 mar 03
> In Susan Peterson's book " The Craft and Art of Clay" she gives a few
> recipes that are formulated for a translucent 04 porcelain clay body,
> and an 04 stone ware body. I have not tried these so I don't know how
> difficult they are. The 04 porcelain is about half frit or cullet. If
> you can't get your hands on the book let me know and I'll email the
> recipes to you.
With all due respect to Susan Peterson and her other fine books, this is one
of the problems with "The Craft and Art of Clay." In the earlier editions
there was a lot of inaccurate information, because the information included
is far beyond her own scope of expertise, so she was trusting others to
provide accurate information, and some of them didn't. I am assuming that
she has corrected most of the misinformation by now, but I can't say for
sure. Regarding the above, I am assuming that it is from one of the earlier
editions, because it is pure unadulterated bullshit. It is completely
impossible to achieve a porcelain or stoneware body at cone 04 unless your
only criteria is degree of vitrification, and that would be absurd. It is
certainly possible to achieve a fritted white or tan body that approaches
vitrification, but it will be brittle and vulnerable, and in no way can it
be called a porcelain or stoneware body.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Office - wpitelka@tntech.edu
615/597-6801 x111, FAX 615/597-6803
http://iweb.tntech.edu/wpitelka/
Paul Herman on thu 6 mar 03
Greetings All,
Vince is right about this. Porcelain and stoneware are High Fired, to
cone 9 and above. So neither does cone 6 porcelain exist. Cone 6 is Mid
Fire. High fired pottery gets a lot of it's strength from mullite
crystals, which do not form at ^6. The glaze/body interface in high
fired ware is more complex and stronger.
I think the 'definition creep' that is taking place is a result of the
popularity of electric kilns. If people insist on making 'porcelain' at
cone 6, there are plenty of suppliers who will be accomodating and call
it 'porcelain', and call cone 6 'high fire'. It's market pressures.
It doesn't fit the definition I use.
best wishes,
Paul Herman
Great Basin Pottery
423-725 Scott Road
Doyle, California 96109 US
potter@psln.com
----------
>From: Vince Pitelka
>
> With all due respect to Susan Peterson and her other fine books, this is one
> of the problems with "The Craft and Art of Clay." In the earlier editions
> there was a lot of inaccurate information, because the information included
> is far beyond her own scope of expertise, so she was trusting others to
> provide accurate information, and some of them didn't. I am assuming that
> she has corrected most of the misinformation by now, but I can't say for
> sure. Regarding the above, I am assuming that it is from one of the earlier
> editions, because it is pure unadulterated bullshit. It is completely
> impossible to achieve a porcelain or stoneware body at cone 04 unless your
> only criteria is degree of vitrification, and that would be absurd. It is
> certainly possible to achieve a fritted white or tan body that approaches
> vitrification, but it will be brittle and vulnerable, and in no way can it
> be called a porcelain or stoneware body.
> - Vince
Jon Pacini on thu 6 mar 03
Greetings all---Hi Vince----On page 148 of Susan Petersen's book 'The Art
and Craft of Clay', Third Edition, under the heading "Historical Clay
Bodies" and the sub heading 'Belleek' is this description:
"This is famous as the most translucent of all chinas, and comes from
Ireland. A porcelain body that can be made paper thin and has almost glass
like transparenency, it is composed of china clay and frits and vitrifies at
low temperatures. The Irish clay body is secret, but try this, cone 04:
china clay 25%, Ball clay 25%, body frit or ground glass 50%."
I believe it was Joanna who sighted this source.
With all due respect to Vince's opinion on this matter----
Susan's book may or may not have inaccuracies in it. However, I
certainly don't see anything inaccurate in this description, in this
context. During the middle centuries of the last millennium, 'soft paste
porcelains' were commonly developed using these types of formulations and
firing ranges.
These bodies are not 'technically analogous' to the high fire porcelain
ware coming out of Asia at the same time. But they are none the less,
historically referred to as porcelains, even if they are of the 'soft paste'
variety.
Splitting hairs, maybe, but I don't think you can take Susan to task on this
particular topic.
Best regards
Jon Pacini
Clay Manager
Laguna Clay Co
Janet Kaiser on fri 7 mar 03
Dear Jon
I know all this is in some way splitting hairs, but note that "China" and
"China Clay" are the operative words here. Susan P. is not claiming Belleek
or any other is true "porcelain". I think that is where there is a HUGE
difference.
Balleek was (and still is) manufactured ware... Again, a HUGE difference in
definition and reference to what potters use and make. Thinness,
translucency (50% glass??) and vitrification are one thing, but what about
(a) the making method: thrown vs mould made and (b) the hardness?
My "take" has always been that the porcelain body has to become "at one"
with the glaze as well as meeting all the other criteria to be considered
"for real". Yes, the low-fire stuff superficially looks like porcelain, but
it lacks that special something... I do not know how to put it into words,
but it just does!
I do not have a problem with Faux Porcelain per se, but I do have a problem
with a low-fired white clay being marketed to makers, who then destroy the
special place that high-fired work has in my heart and that of many others,
including serious collectors. Make something run-of-the-mill and it pulls
the rug from under the feet of the few who depend on the celebrity status
of "true porcelain". It undermines them and that is neither fair nor
acceptable IMO.
Furthermore, I cannot personally see the benefit in this course, but I can
see a lot of reasons why both clay producers/manufacturers and those
starting out should respect the high regard the high-fired, thrown and
sculpted true porcelain users command. It also removes another level of
competency to aspire to... A sort of dumbing down, which I have never
subscribed to.
As you say, the term "porcelain" is interchangeable historically speaking,
but as most on Clayart are not manufacturing in the footsteps of Meissen or
even Belleek, but are studio potters, I think that a line should be drawn
in the sand. I would love you and other clay producers to up the stakes on
this one! Make your customers aware that there is a very super special clay
that only the very best and most highly skilled will ever be able to cope
with... "True Porcelain"... The white gold.
BTW I always think of the early days man-made materials when I rant on
about "natural" and "real"... The US embraced these products and it is
still possible to recognise US citizens at 50 paces because of it. Here in
Europe, we flirted with them, but then decided that cotton, wool, linen,
silk and even wood were preferable to anything made from oil...
We definitely have a "mind set" issue here.
Sincerely
Janet Kaiser
*** IN REPLY TO THE FOLLOWING MAIL:
*** From: Jon Pacini
*** E-address: jpacini@LAGUNACLAY.COM
*** Sent: 06/03/03 Time: 11:22
>Greetings all---Hi Vince----On page 148 of Susan Petersen's book 'The Art
>and Craft of Clay', Third Edition, under the heading "Historical Clay
>Bodies" and the sub heading 'Belleek' is this description:
>
>"This is famous as the most translucent of all chinas, and comes from
>Ireland. A porcelain body that can be made paper thin and has almost glass
>like transparenency, it is composed of china clay and frits and vitrifies
>at
>low temperatures. The Irish clay body is secret, but try this, cone 04:
>china clay 25%, Ball clay 25%, body frit or ground glass 50%."
>
>I believe it was Joanna who sighted this source.
>
>With all due respect to Vince's opinion on this matter----
> Susan's book may or may not have inaccuracies in it. However, I
>certainly don't see anything inaccurate in this description, in this
>context. During the middle centuries of the last millennium, 'soft paste
>porcelains' were commonly developed using these types of formulations and
>firing ranges.
> These bodies are not 'technically analogous' to the high fire
porcelain
>ware coming out of Asia at the same time. But they are none the less,
>historically referred to as porcelains, even if they are of the 'soft
>paste'
>variety.
>
>Splitting hairs, maybe, but I don't think you can take Susan to task on
>this
>particular topic.
>
>Best regards
>Jon Pacini
>Clay Manager
>Laguna Clay Co
*** THE MAIL FROM Jon Pacini ENDS HERE ***
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