Paul Lewing on sun 30 aug 09
I'm forwarding this thread to the Porcelain Painters International
Online list for china painters, because they're interested in
porcelain too.
When I started writing "China Paint & Overglaze" I found that this was
a huge problem for me. Both groups used the word but they meant
different things by it. Mel pretty well laid out the typical potter's
definition of porcelain. China painters recognize three different
kinds of porcelain (or at least some, but not all, of them do). They
are hard-paste, soft-paste, and bone china. Hard paste would be
exactly what Mel described: fired to at least cone 9, really white,
really fine grain, and at least partially translucent.
Soft paste porcelain, on the other hand is usually fired below cone 1,
and bone china is somewhere in between. I once had a china painter
say, when I asked if a particular piece was porcelain, "Oh yes, it's
high fired up to cone 1". China painters who make or glaze their own
pieces virtually never fire above cone 6.
To complicate things further, there's another group (which I also deal
with a lot) who have their own definition of porcelain, and that's the
tile industry. Unlike potters or china painters, they actually have
an empirical definition of what makes porcelain. It's any clay with
less than 0.1% water absorbency. In practice that usually means high
fired, although they usually will not tell you how high. But the
definition does not preclude it being lowfire if you can figure out
how to get that low an absorbency. It also says nothing about color
or translucency. So the market is full of porcelain floor tiles in
every shade from cream to grey to buff to terra cotta to chocolate to
black, and none of them is translucent.
So, is it porcelain? Depends on who you ask. That's why I titled the
Foreword to my book "A Few Words About Words". "Bisque" was another
word there was not agreement on.
Paul Lewing
www.paullewingtile.com
www.paullewingart.com
mel jacobson on sun 30 aug 09
a good topic to discuss.
i am a bit of a purest, and think that porcelain is a
very high fire ceramic. like cone 11+.
cone 6 white is stoneware in my book.
it is about heat, and mid range, is mid range, no matter the color.
i find many people at fairs calling mid/range/cone 5 white as
`PORCELAIN BY JENNIE`.
i find that calling it stoneware is not a negative.
but, some think that people will buy more if they say
PORCELAIN. that to me is cheating the public.
high fired, very vitrified porcelain is a very special sort
of ceramic work in my opinion. ( and it takes a great potter
with great skill to make it perfect.)
mel
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
new book: http://www.21stcenturykilns.com
Randall Moody on sun 30 aug 09
On Sun, Aug 30, 2009 at 5:51 PM, mel jacobson wrote:
> a good topic to discuss.
>
> i am a bit of a purest, and think that porcelain is a
> very high fire ceramic. like cone 11+.
>
> cone 6 white is stoneware in my book.
>
> it is about heat, and mid range, is mid range, no matter the color.
>
> i find many people at fairs calling mid/range/cone 5 white as
> `PORCELAIN BY JENNIE`.
>
> i find that calling it stoneware is not a negative.
>
> but, some think that people will buy more if they say
> PORCELAIN. that to me is cheating the public.
>
> high fired, very vitrified porcelain is a very special sort
> of ceramic work in my opinion. ( and it takes a great potter
> with great skill to make it perfect.)
> mel
>
>
I agree that porcelain should be high fire rather than just white. I guess
that I should have added that I am using cone 10 B-mix. I don't really thin=
k
of it a porcelain though. Maybe "dirty porcelain"?
--
Randall in Atlanta
John Rodgers on sun 30 aug 09
In my book, stoneware is stoneware and porcelain is porcelain - be they
cone 6 or cone 10-11-12. All the way from cone 6 to cone 12 porcelain is
in my mind distinctly different from stoneware. B-mix - be it C-5 or
C-10 ,just isn't ever going to be porcelain, though is may have some
similar characteristics. Porcelain will be sonorous if thin, and
translucent if thin, and well vitrified to the point of being some what
glass like. And - in my mind at least - porcelain is "white" even if not
translucent. In the world of figurine work, I have never seen a
porcelain fired to a cone ten though I suppose it could be done and may
have been done. Most is fired to C-6. But mostly we talk of pottery
here, and admittedly, porcelain figurine work is a bit different - a
whole 'nother realm in the world of clay. In figurine work you typically
fire to maturity first - C-6, - then come back with surface coats -
glaze and china paints - fired in the range of C-020 to C-06. Backward
from most pottery.
John Rodgers
Chelsea, AL
mel jacobson wrote:
> a good topic to discuss.
>
> i am a bit of a purest, and think that porcelain is a
> very high fire ceramic. like cone 11+.
>
> cone 6 white is stoneware in my book.
>
> it is about heat, and mid range, is mid range, no matter the color.
>
> i find many people at fairs calling mid/range/cone 5 white as
> `PORCELAIN BY JENNIE`.
>
> i find that calling it stoneware is not a negative.
>
> but, some think that people will buy more if they say
> PORCELAIN. that to me is cheating the public.
>
> high fired, very vitrified porcelain is a very special sort
> of ceramic work in my opinion. ( and it takes a great potter
> with great skill to make it perfect.)
> mel
>
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link: http://www.visi.com/~melpots/clayart.html
> new book: http://www.21stcenturykilns.com
>
>
May Luk on sun 30 aug 09
B-Mix type clay is called "super white" stoneware in England. Some potters
call this type of clay half-porcelain. It sounds funny to me, but whatever
works for their marketing effort.
I use B-mix cone 10, and I call it stoneware.
A few customers have expressed reservations about porcelain, they think it'=
s
too fragile for every day use. Sometimes, you never know what your
customers' perception of ceramics.
May
Brooklyn NY
>>>>>>>>>>>>>>>>>>>>>>
>
> I agree that porcelain should be high fire rather than just white. I gues=
s
> that I should have added that I am using cone 10 B-mix. I don't really
> think
> of it a porcelain though. Maybe "dirty porcelain"?
>
> --
> Randall in Atlanta
>
--
http://twitter.com/MayLuk
http://www.flickr.com/groups/handmade_mugs/
Des & Jan Howard on mon 31 aug 09
Mel & John
The term that the word 'porcelain' is derived from was
applied to ware that was 'white, thin & translucent'.
Not to a temp range, not to a formulation.
Our white clay body is:
Snow-white, vitreous from Cone 10, translucent when
thin, sonorous even when thick & heavily glazed.
We don't usually make thin pots.
We call it 'white porcelaneous stoneware'.
Earthenware is fired ~1080C, stoneware ~1280C, so
mid-range would be ~1180C Cone 3-4.
Some of the much-loved, (& justifiably so, I might
add), Oriental ware such as Ru, Jun & Guan weren't
fired much higher than this. Ding ware, the first true
porcelain, wasn't fired much above 1280C
The current trend for Cone 6 at ~1230C is just an
attempt at 'greenishness' in ceramics, a token
reduction in resource usage, but if the clay body is
'white, thin & translucent', I guess it's porcelain
Des
--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850
02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624
Ric Swenson on mon 31 aug 09
from what I have learned...
=3D20
Earthenware/terracotta is surface/brick clay fired at lower temperatures a=
=3D
s cone 010-01 and reddish/brown when fired...quite absorbant of water.
=3D20
Stoneware is not quite WHITE...shades of gray to brown and even black (basa=
=3D
lt) fired from cone 1 to cone 10
vitrified and glass-like at it's peak temp. Less than 2 % absorbtion.... su=
=3D
itable for tablewares. A Secondary clay.
=3D20
Porcelain....always white...after fired...pure...no iron specks or other co=
=3D
ntaminants....always less than about 1 % absorbtion ...of H2O upon testing.=
=3D
.
Quite vitrified and glasslike. Very smooth and do not contain sand or grog.=
=3D
Hard to throw and make thin without trimming a lot. Like throwing room te=
=3D
mp butter....hehe.
=3D20
known as CHINA...usually fired at cone 9-13. Gao Ling mountain near JingDe=
=3D
Zhen.... was the original deposit discovered by humans of a perfect porcela=
=3D
in ( also named by the Portuguese merchants from Porcelena...a white shell =
=3D
of great white purity and we recognize now as.... Kaolin clay) A prim=
=3D
ary clay of unusually and remarkable purity. granite rock that broke down o=
=3D
ver tens of thousands of years in the same place and was not carried by waa=
=3D
ter/stream/erosion to other lower locations...river beds...etc...
=3D20
the term ''China' originated from the Portuguese merchants who described wh=
=3D
ere it came from.....'ChanNan' (China) which was the original name for Jin=
=3D
geDeZhen before 1004 AD.=3D20
=3D20
=3D20
The Emperor of China at that time ...gave the name of his reign to 'JingDe=
=3D
'Zhen=3D2C the only city in China with such an honor.
=3D20
Porcelain can appear a little greyish in reduction fire...unless saggered. =
=3D
All wares made for the Emperor were fired in saggers....in wood fires. Cone=
=3D
11-13
=3D20
=3D20
Whitish stonewares or Low fire-White bodies using talc are not any form of =
=3D
real 'porcelain'....IMHO.
=3D20
JingDeZhen porcelain is said to be: "thin as paper=3D2C white as fine jade=
=3D2C=3D
sounds as a bell and as bright as a mirror."
=3D20
=3D20
=3D20
My 2 cents.
=3D20
=3D20
Ric
=3D20
=3D20
=3D20
=3D20
=3D20
=3D20
=3D20
"...then fiery expedition be my wing=3D2C ..."=3D20
-Wm. Shakespeare=3D2C RICHARD III=3D2C Act IV Scene III=3D20
=3D20
Richard H. ("Ric") Swenson=3D2C Teacher=3D2C=3D20
Office of International Cooperation and Exchange of Jingdezhen Ceramic Inst=
=3D
itute=3D2C=3D20
TaoYang Road=3D2C Eastern Suburb=3D2C Jingdezhen City.
JiangXi Province=3D2C P.R. of China.=3D20
Postal code 333001.=3D20
Mobile/cellular phone : 86 13767818872=3D20
< RicSwenson0823@hotmail.com>
=3D20
http://www.jci.jx.cn/
http://www.ricswenson.com
=3D20
> Date: Sun=3D2C 30 Aug 2009 21:47:47 -0400
> From: claywedgie@GMAIL.COM
> Subject: Re: call it porcelain maybe?
> To: Clayart@LSV.CERAMICS.ORG
>=3D20
> B-Mix type clay is called "super white" stoneware in England. Some potter=
=3D
s
> call this type of clay half-porcelain. It sounds funny to me=3D2C but wha=
te=3D
ver
> works for their marketing effort.
>=3D20
> I use B-mix cone 10=3D2C and I call it stoneware.
>=3D20
> A few customers have expressed reservations about porcelain=3D2C they thi=
nk=3D
it's
> too fragile for every day use. Sometimes=3D2C you never know what your
> customers' perception of ceramics.
>=3D20
> May
> Brooklyn NY
>=3D20
>=3D20
> >>>>>>>>>>>>>>>>>>>>>>
>=3D20
> >
> > I agree that porcelain should be high fire rather than just white. I gu=
=3D
ess
> > that I should have added that I am using cone 10 B-mix. I don't really
> > think
> > of it a porcelain though. Maybe "dirty porcelain"?
> >
> > --
> > Randall in Atlanta
> >
>=3D20
>=3D20
>=3D20
> --
> http://twitter.com/MayLuk
> http://www.flickr.com/groups/handmade_mugs/
_________________________________________________________________
More than messages=3D96check out the rest of the Windows Live=3D99.
http://www.microsoft.com/windows/windowslive/=3D
Des & Jan Howard on mon 31 aug 09
Ric
Your reference books & my reference books
don't quite agree.
Porcelain in North China came from seat earth materials
of the coal deposits. Porcelain around your area of
JingDeZhen came from hydrothermally altered rock,
bai-tunze, to which was added the material from Gao
Ling around Ming times to augment the fading marginal
plasticity.
The word 'porcelain' derives from 'porcellana',
derived from 'porcello',little pig, referring to
a white, translucent cowrie shell,
which is shaped like a sow's vulva.
But then I've been wrong before.
Des
Ric Swenson wrote:
> known as CHINA...usually fired at cone 9-13.
> Gao Ling mountain near JingDeZhen....
> was the original deposit discovered by humans
> of a perfect porcelain ( also named by the Portuguese
> merchants from Porcelena...a white shell of great
> white purity and we recognize now as.... Kaolin clay)
> A primary clay of unusually and remarkable purity.
> granite rock that broke down over tens of thousands
> of years in the same place and was not carried by
> waater/stream/erosion to other lower locations...river beds...etc...
--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850
02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624
Steve Slatin on mon 31 aug 09
This is always a somewhat sore point ... it
appears to me that it isn't a well-defined
thing in the public's mind and is a differently
defined thing in the minds of many potters.
Joe Brecia (of Tacoma Clay Arts) makes=3D20
a B-Mix work-alike clay called OH-6. It
matures at 6 rather than 5, and has (IMHO)
even better color response than B-Mix.
He calls it a 'dirty porcelain.' It rings
very nicely, though several of his stonewares
ring very nicely also ... it is somewhat
glass-like, though it doesn't 'pluck' as
much as some porcelains do. And it doesn't
get the sudden-state-of-collapse effect
that some porcelains get when being thrown
thin. It is not quite as smooth where
unglazed as porcelain.
With some glazes it has almost exactly the
same surface and color effects that 'true'
porcelains have (if you accept that something
like Awaji Cone 6 is actually a porcelain, I
don't fire to cone 10 just to test the=3D20
differences). =3D20
To avoid confusion, I tell my clients that
it's a 'white stoneware.' Like Mel, I find
this avoids misunderstandings without=3D20
harming sales, and I prefer
not to claim a title -- porcelain -- that=3D20
could be argued. No one can argue the
accuracy of 'white stoneware.'
Steve Slatin --=3D20
--- On Sun, 8/30/09, John Rodgers wrote:
> In my book, stoneware is stoneware
> and porcelain is porcelain - be they
> cone 6 or cone 10-11-12. All the way from cone 6 to cone 12
> porcelain is
> in my mind distinctly different from stoneware. B-mix - be
> it C-5 or
> C-10 ,just isn't ever going to be porcelain, though is may
> have some
> similar characteristics. Porcelain will be sonorous if
> thin, and
> translucent if thin, and well vitrified to the point of
> being some what
> glass like. And - in my mind at least - porcelain is
> "white" even if not
> translucent.=3DA0 In the world of figurine work, I have
> never seen a
> porcelain fired to a cone ten though I suppose it could be
> done and may
> have been done.=3DA0=3DA0=3DA0Most is fired to
> C-6.=3DA0 But mostly we talk of pottery
> here, and admittedly, porcelain figurine work is a bit
> different - a
> whole 'nother realm in the world of clay. In figurine work
> you typically
> fire to maturity first - C-6, - then come back with surface
> coats -
> glaze and china paints - fired in the range=3DA0 of C-020
> to C-06. Backward
> from most pottery.
>=3D20
> John Rodgers
> Chelsea, AL
=3D0A=3D0A=3D0A
John Rodgers on mon 31 aug 09
Paul,
I am glad you addressed this issue. It has plagued me from the
beginning of my clay career - because I came into the clay world as a
slipcaster working with ^6 porcelains for figurines. At the time I knew
absolutely nothing about pottery or pottery grade porcelain clays. It
has been an ongoing education. And obviously - the debate over a
definition for porcelain continues.
Regards.
John Rodgers
Chelsea, aL
Paul Lewing wrote:
> I'm forwarding this thread to the Porcelain Painters International
> Online list for china painters, because they're interested in
> porcelain too.
>
> When I started writing "China Paint & Overglaze" I found that this was
> a huge problem for me. Both groups used the word but they meant
> different things by it. Mel pretty well laid out the typical potter's
> definition of porcelain. China painters recognize three different
> kinds of porcelain (or at least some, but not all, of them do). They
> are hard-paste, soft-paste, and bone china. Hard paste would be
> exactly what Mel described: fired to at least cone 9, really white,
> really fine grain, and at least partially translucent.
> Soft paste porcelain, on the other hand is usually fired below cone 1,
> and bone china is somewhere in between. I once had a china painter
> say, when I asked if a particular piece was porcelain, "Oh yes, it's
> high fired up to cone 1". China painters who make or glaze their own
> pieces virtually never fire above cone 6.
> To complicate things further, there's another group (which I also deal
> with a lot) who have their own definition of porcelain, and that's the
> tile industry. Unlike potters or china painters, they actually have
> an empirical definition of what makes porcelain. It's any clay with
> less than 0.1% water absorbency. In practice that usually means high
> fired, although they usually will not tell you how high. But the
> definition does not preclude it being lowfire if you can figure out
> how to get that low an absorbency. It also says nothing about color
> or translucency. So the market is full of porcelain floor tiles in
> every shade from cream to grey to buff to terra cotta to chocolate to
> black, and none of them is translucent.
> So, is it porcelain? Depends on who you ask. That's why I titled the
> Foreword to my book "A Few Words About Words". "Bisque" was another
> word there was not agreement on.
> Paul Lewing
> www.paullewingtile.com
> www.paullewingart.com
>
>
Hank Murrow on mon 31 aug 09
Dear Des and Ric;
Des is correct, the original deposits of Bai-tunze were of volcanic
origin, and highly weathered when discovered. This material was
Rhyolitic, white, and had around 3_4% alkali content, which made it a
beautiful porcelain body. As the weathered Rhyolite was mined, it got
down to less weathered rock and they had to add kaolin to create
enough plasticity to work well. At the same time, they needed to add
some feldspar to make up for the then missing alkali. At present,
the Jingdezhen bodies only have around 30% Bai-tunze. David Stannard
visited these deposits in 1972, and went down 1/4 mile into a Bai-
tunze mine collecting samples along the way. These were later given x-
ray diffraction analysis and other testing, to confirm David's
guesses concerning the origins and history of the material. He has
since prospected many deposits of Rhyolitic rock and found natural
porcelains from Oregon to Alaska. Very promising work on behalf of
potters who love to use the rocks on hand, like Des. I am lucky to
live near a weathered and altered Rhyolite deposit that provides the
lovely Calf Ridge porcelainstone, which David prospected.
Now for the bad news....... David Stannard succumbed to brain cancer
around 2 Sunday morning in Eugene, OR with Noel Osheroff with him,
and his son Sean Stannard arriving a bit later. It is a tragedy that
his work remains unfinished, though a small book was completed a
couple of years ago, which summarizes his life and work, and which I
hope to give broader distribution than he did.
It is called "Dancing in Two Worlds".... Energy, Environment, &
Education; and is available in two versions on a CD....for viewing or
printing. Thus, one can read it on a screen or have Kinko's print it
for you into a small 42 page booklet with illustrations.
Cheers on this sad day........ Hank in Eugene
On Aug 31, 2009, at 6:42 AM, Des & Jan Howard wrote:
> Ric
> Your reference books & my reference books don't quite agree.
> Porcelain in North China came from seat earth materials
> of the coal deposits.
> Porcelain around your area of JingDeZhen came from hydrothermally
> altered rock, bai-tunze, to which was added the material from Gao
> Ling around Ming times to augment the fading marginal plasticity.
Neon-Cat on mon 31 aug 09
This is an interesting article from 1998 that covers a lot of ground even e=
=3D
xperienced potters should enjoy traveling along for a short spell.=3D20
"Porcelain-Raw Materials, Processing, Phase Evolution, and Mechanical Behav=
=3D
ior"
William M. Cam and Udayan Senapati
New York State College of Ceramics at Alfred University, Alfred, New York=
=3D
=3D20
http://www.aytacbicer.com/TR/DersNotlari/Whitewares/williampdf.pdf=3D20
Triaxial whitewares, anyone?
Enjoy!
Marian=3D20
Neon-Cat=3D20
www.neon-cat.com =3DA0
ivor & olive lewis on tue 1 sep 09
Marian,
Good to see you back on the block again. Welcome back.
Thanks for posting the URL for :
"Porcelain-Raw Materials, Processing, Phase Evolution, and Mechanical
Behaviour" by William Carty and Udayan Senapati. Made a hard copy of that
one.
One fine day someone will start to consider the significance of Water and
its contribution to the formation of floc structures and the propagation o=
f
motion in plastic clay.
Best regards,
Ivor Lewis,
Redhill,
South Australia
Neon-Cat on tue 1 sep 09
Ivor, the nature of free-spirited ferals is to roam. Sometimes we leave lit=
tle gifts from midnight play as evidence of our passing -- this time a porc=
elain article, next time perhaps a dead mouse...
Glad you liked Carty and Senapati.
Water? Every potter in the world, fine day or not, considers the significan=
ce of water during the course of their activities. Further depth to the top=
ic can be had in numerous already available publications.
Marian
Neon-Cat
--------------
Marian,
Good to see you back on the block again. Welcome back.
Thanks for posting the URL for :
"Porcelain-Raw Materials, Processing, Phase Evolution, and Mechanical
Behaviour" by William Carty and Udayan Senapati. Made a hard copy of that
one.
One fine day someone will start to consider the significance of Water and
its contribution to the formation of floc structures and the propagation of
motion in plastic clay.
Best regards,
Ivor Lewis,
Redhill,
South Australia
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