Ann Baker on mon 30 apr 07
I have been looking into changing to a new cone 6 clay and noticed one of
the cone 6 porcelains I am considering is described as containing no ball
clay. Why is this a point of "advertising"? What does the addition of or
lack of ball clay do to porcelain?
Happy Potting, annb
Lois Ruben Aronow on mon 30 apr 07
Having ball clay in your porcelain makes it...not really porcelain. True
porcelain contains no ball clay. Some people might consider this
"porcelaneous stoneware", but that is quite a mouthful.
It is whiter than stoneware, but not as white as grolleg. It is probably
more plastic and easier to throw, in addition to shrinking a tad less.
I'm sure I've left out something here, and I'm sure someone will jump in and
either finish or correct it.
...lo
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ann Baker
> Sent: Monday, April 30, 2007 11:57 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: ball clay in porcelain?
>
> I have been looking into changing to a new cone 6 clay and
> noticed one of the cone 6 porcelains I am considering is
> described as containing no ball clay. Why is this a point of
> "advertising"? What does the addition of or lack of ball clay
> do to porcelain?
>
> Happy Potting, annb
>
> ______________________________________________________________
> ________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your
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>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Thomas Malone on mon 30 apr 07
Hi Ann,
The big negative with having a ball clay in a porcelain body is the high
levels of Fe2O3 and TiO2 that these clays invariably have in comparison to
the highest quality kaolins. These oxides reduce whiteness and translucency
after firing. It is for the same reason that secondary kaolins, such as
those mined in the US, are inferior for porcelain compared to primary
kaolins like those found in England.
Dinah Steveni on mon 30 apr 07
I can't buy this: . You will find that
small amounts of ball clay have always been added for plasticity and dry
strength.
Dinah Steveni
----- Original Message -----
From: "Lois Ruben Aronow"
To:
Sent: Monday, April 30, 2007 2:20 PM
Subject: Re: ball clay in porcelain?
> Having ball clay in your porcelain makes it...not really porcelain. True
> porcelain contains no ball clay. Some people might consider this
> "porcelaneous stoneware", but that is quite a mouthful.
>
> It is whiter than stoneware, but not as white as grolleg. It is probably
> more plastic and easier to throw, in addition to shrinking a tad less.
>
> I'm sure I've left out something here, and I'm sure someone will jump in
and
> either finish or correct it.
>
> ...lo
>
> > -----Original Message-----
> > From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Ann Baker
> > Sent: Monday, April 30, 2007 11:57 AM
> > To: CLAYART@LSV.CERAMICS.ORG
> > Subject: ball clay in porcelain?
> >
> > I have been looking into changing to a new cone 6 clay and
> > noticed one of the cone 6 porcelains I am considering is
> > described as containing no ball clay. Why is this a point of
> > "advertising"? What does the addition of or lack of ball clay
> > do to porcelain?
> >
> > Happy Potting, annb
> >
> > ______________________________________________________________
> > ________________
> > 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.
Ivor Lewis on tue 1 may 07
Dear Ann Baker,
Ball clay, being a sedimentary material, may contain residual minerals that
would prevent the development of translucency or cause discolouration in a
porcelain body. Exclusion of this raw material often reduces the degree of
plasticity of a clay/ water paste. So manufacturers look for "Plastic
Kaolin" or now add another clay mineral "Halloysite" to improve plasicity.
Best regards,
Ivor
Ann Baker on tue 1 may 07
AHHH! thank you, that helps me understand.
Thomas Malone on wed 2 may 07
Hello Russell, and I would weigh in here with:
There is no universally agreed defintion of 'porcelain.'
Even those porcelains that some call 'true' may have been composed using
kaolin, or kaolin mixed with other materials.
Petunse is not 'A' rock it is a very losse description of a many different
rocks that share some similarity and useage.
The name petunse is now more of historic useage, with other names being now
used.
Marcia Selsor on wed 2 may 07
For some reason my posts haven't been getting to clayart.
I have a story dating back to WWI regarding ball clay in French
porcelain.
I was in a museum in 1972 in Paducah, Kentucky talking with a man
from the local arts organization.
Kentucky Ball Clays are mined not far from there. He was trying to
i,press on us the purity of kentucky ball clays.
His father or grandfather had been wounded in WWI and was being
treated by a French doctor. When he told
the doctor he was from paducah, KT. the doctor responded that he
knew of Paducah.
His (the doctor's) family was in the porcelain manufacturing business
and they imported KT Ball Clay for their
porcelain. It is the purest ball clay in the world..according to
the doctor.
So evidently, some porcelains do have ball clay in them.
Marcia Selsor
http://marciaselsor.com
Russel Fouts on wed 2 may 07
>> I can't buy this: . You will
find that small amounts of ball clay have always been added for
plasticity and dry strength. <<
Hank should weigh in here.
'True porcelain' doesn't contain ball clay OR Kaolin.
'True porcelain' is a rock called Petunse.
Russel
Russel Fouts
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