Michael Wendt on fri 18 may 07
Elizabeth,
I will agree with your definition with
one proviso:
The whiteness standard needs to be
set at a fairly high level.
What whiteness do you recommend?
GE 84?
GE 87?
GE 90?
Whiteness is a quality that
can actually be measured.
Light transmission per cross-
section can also be measured.
Absorption can be measured.
It's odd though that unlike
the term "hand made" which
can be observed directly by
inspection, the characteristics
of a porcelain require extensive
tests to quantify its characteristics
and those test results always
fall on a continuum of values.
If you are willing to define the
parameters tightly enough, only
a few clay formulations will meet
all of the criteria to be called
porcelain.
Recent research with Helmer Kaolin
has found a way to remove enough
of the iron-titanium contaminant to
get a GE90 + fired color if people
were willing to pay the price for it.
If you set the standard that high would
GE 84 porcelain no longer be porcelain?
Just asking.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, ID 83501
USA
208-746-3724
http://www.wendtpottery.com
wendtpot@lewiston.com
Elizabeth wrote:
I consider porcelain very high fired translucent clay
with
virtually no inclusions making for a pure white clay
body.
But that is just me, apparently !
Thanks for that information.
Elizabeth Priddy
Beaufort, NC - USA
Paul Lewing on sat 19 may 07
On May 18, 2007, at 10:05 AM, Elizabeth Priddy wrote:
And they call it porcelain. And it is
by some technical standard. But we all know what real porcelain
is,
Actually we don't. One of the first things I found out when I was
researching my book on china paint was that potters, china painters,
the dinnerware industry and the tile industry all mean different
things by the word porcelain. Potters are pretty well agreed (more
or less) on what they mean by the word, and it would be about the
definition one would find in something like Hamer & Hamer. Even
then, some potters think porcelain has to be really white; others
don't. Some potters think it has to be fired above cone 8; others
don't. Some potters think it has to be translucent; others don't.
China painters sometimes refer to stuff fired as low as cone 04 as
porcelain. A lot of what the dinnerware industry calls porcelain
potters might call white stoneware. Of the whole bunch of them, the
tile industry is the only one that has an actual quantifiable test
for what it porcelain. Their definition says only that it must have
less than 0.3% water absorbency. No reference to firing temperature
(although the definition pretty much necessitates high temperature)
or translucency, or color. You should see what is being sold as
porcelain tile these days. Almost none of it is white, and some of
it is as dark brown as chocolate. Is that porcelain? It is by their
definition.
Paul Lewing
www.paullewingtile.com
Elizabeth Priddy on sat 19 may 07
Well, there you have it!
This is a pretty good demonstration that there are as many
loose definitions of porcelain in the ceramic world as there
are "hand-made" in the marketed wares world.
And why would a term that ought to have a solid definition
be in such a grey area? Because a lot of people want what
they are doing to be porcelain and no industry standard to
go by, except those tile people.
I consider porcelain very high fired translucent clay with
virtually no inclusions making for a pure white clay body.
But that is just me, apparently !
Thanks for that information.
Elizabeth Priddy
Beaufort, NC - USA
Natural Instincts Conference Registration Information:
http://www.ceramics.org/potterscouncil/naturalinstincts/registrationinfo.asp
http://www.elizabethpriddy.com
http://www.flickr.com/photos/7973282@N03/
----- Original Message ----
From: Paul Lewing
To: CLAYART@LSV.CERAMICS.ORG
Sent: Saturday, May 19, 2007 7:33:59 PM
Subject: Re: Porcelain (was worth having)
On May 18, 2007, at 10:05 AM, Elizabeth Priddy wrote:
And they call it porcelain. And it is
by some technical standard. But we all know what real porcelain
is,
Actually we don't. One of the first things I found out when I was
researching my book on china paint was that potters, china painters,
the dinnerware industry and the tile industry all mean different
things by the word porcelain. Potters are pretty well agreed (more
or less) on what they mean by the word, and it would be about the
definition one would find in something like Hamer & Hamer. Even
then, some potters think porcelain has to be really white; others
don't. Some potters think it has to be fired above cone 8; others
don't. Some potters think it has to be translucent; others don't.
China painters sometimes refer to stuff fired as low as cone 04 as
porcelain. A lot of what the dinnerware industry calls porcelain
potters might call white stoneware. Of the whole bunch of them, the
tile industry is the only one that has an actual quantifiable test
for what it porcelain. Their definition says only that it must have
less than 0.3% water absorbency. No reference to firing temperature
(although the definition pretty much necessitates high temperature)
or translucency, or color. You should see what is being sold as
porcelain tile these days. Almost none of it is white, and some of
it is as dark brown as chocolate. Is that porcelain? It is by their
definition.
Paul Lewing
www.paullewingtile.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.
____________________________________________________________________________________Give spam the boot. Take control with tough spam protection in the all-new Yahoo! Mail Beta.
http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
David Beumee on sun 20 may 07
Elizabeth,
I very muchh appreciate your comments, as I value Paul's comments as well. Your statement rings true from the perspective of one who has used a porcelain clay body without the addition of ball clay for decades.
"And why would a term that ought to have a solid definition be in such a grey area? Because a lot of people want what they are doing to be porcelain and no industry standard to go by, except those tile people."
From my perspective it is very sad that chocolate brown tile is called porcelain, just because it is fired to vitrification. Potters have trusted Hamer with definitions for many years, and I not only trust their definition of porcelain but know it to be true: "A vitrified, WHITE and translucent ware." When I see so many wanting to make what they are using porcelain, I will think again of your above statement and smile.
"I consider porcelain very high fired translucent clay with
virtually no inclusions making for a pure white clay body."
Well said and true, but others will vehemently disagree, as has happened in many rounds of discussion on Clayart.
David Beumee
Porcelain by David Beumee
www.davidbeumee.com
Lafayette, CO
>
> This is a pretty good demonstration that there are as many
> loose definitions of porcelain in the ceramic world as there
> are "hand-made" in the marketed wares world.
>
> And why would a term that ought to have a solid definition
> be in such a grey area? Because a lot of people want what
> they are doing to be porcelain and no industry standard to
> go by, except those tile people.
>
> I consider porcelain very high fired translucent clay with
> virtually no inclusions making for a pure white clay body.
>
> But that is just me, apparently !
>
> Thanks for that information.
>
> Elizabeth Priddy
> Beaufort, NC - USA
>
> Natural Instincts Conference Registration Information:
>
> http://www.ceramics.org/potterscouncil/naturalinstincts/registrationinfo.asp
>
> http://www.elizabethpriddy.com
> http://www.flickr.com/photos/7973282@N03/
>
>
> ----- Original Message ----
> From: Paul Lewing
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Saturday, May 19, 2007 7:33:59 PM
> Subject: Re: Porcelain (was worth having)
>
>
> On May 18, 2007, at 10:05 AM, Elizabeth Priddy wrote:
> And they call it porcelain. And it is
> by some technical standard. But we all know what real porcelain
> is,
>
> Actually we don't. One of the first things I found out when I was
> researching my book on china paint was that potters, china painters,
> the dinnerware industry and the tile industry all mean different
> things by the word porcelain. Potters are pretty well agreed (more
> or less) on what they mean by the word, and it would be about the
> definition one would find in something like Hamer & Hamer. Even
> then, some potters think porcelain has to be really white; others
> don't. Some potters think it has to be fired above cone 8; others
> don't. Some potters think it has to be translucent; others don't.
> China painters sometimes refer to stuff fired as low as cone 04 as
> porcelain. A lot of what the dinnerware industry calls porcelain
> potters might call white stoneware. Of the whole bunch of them, the
> tile industry is the only one that has an actual quantifiable test
> for what it porcelain. Their definition says only that it must have
> less than 0.3% water absorbency. No reference to firing temperature
> (although the definition pretty much necessitates high temperature)
> or translucency, or color. You should see what is being sold as
> porcelain tile these days. Almost none of it is white, and some of
> it is as dark brown as chocolate. Is that porcelain? It is by their
> definition.
> Paul Lewing
> www.paullewingtile.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.
>
>
>
> ________________________________________________________________________________
> ____Give spam the boot. Take control with tough spam protection in the all-new
> Yahoo! Mail Beta.
> http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
>
> ______________________________________________________________________________
> 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.
Charles Hightower on sun 20 may 07
Although it would be poorly thrown, one could throw
the rim of a bowl thin enough to be translucent and
the rest not. Is the rim porcelain and the rest white
stoneware? And what of all the wonderful work people
are doing with colored porcelains? Nice translucency,
but it's blue! It's not white so it can't be
porcelain? Things change with time. The porcelains we
use today are far different than the porcelains used
centuries ago. There is and always have been different
types of porcelains. Hard paste, soft paste, or bone
china. Whats to say we can't expand that just a little
wider? Many already are. To me, a porcelain body is a
matter of formula and vitrification.
--- David Beumee wrote:
> Elizabeth,
> I very muchh appreciate your comments, as I value
> Paul's comments as well. Your statement rings true
> from the perspective of one who has used a porcelain
> clay body without the addition of ball clay for
> decades.
>
> "And why would a term that ought to have a solid
> definition be in such a grey area? Because a lot of
> people want what they are doing to be porcelain and
> no industry standard to go by, except those tile
> people."
>
> From my perspective it is very sad that chocolate
> brown tile is called porcelain, just because it is
> fired to vitrification. Potters have trusted Hamer
> with definitions for many years, and I not only
> trust their definition of porcelain but know it to
> be true: "A vitrified, WHITE and translucent ware."
> When I see so many wanting to make what they are
> using porcelain, I will think again of your above
> statement and smile.
>
> "I consider porcelain very high fired translucent
> clay with
> virtually no inclusions making for a pure white
> clay body."
>
> Well said and true, but others will vehemently
> disagree, as has happened in many rounds of
> discussion on Clayart.
>
>
> David Beumee
> Porcelain by David Beumee
> www.davidbeumee.com
> Lafayette, CO
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> >
> > This is a pretty good demonstration that there are
> as many
> > loose definitions of porcelain in the ceramic
> world as there
> > are "hand-made" in the marketed wares world.
> >
> > And why would a term that ought to have a solid
> definition
> > be in such a grey area? Because a lot of people
> want what
> > they are doing to be porcelain and no industry
> standard to
> > go by, except those tile people.
> >
> > I consider porcelain very high fired translucent
> clay with
> > virtually no inclusions making for a pure white
> clay body.
> >
> > But that is just me, apparently !
> >
> > Thanks for that information.
> >
> > Elizabeth Priddy
> > Beaufort, NC - USA
> >
> > Natural Instincts Conference Registration
> Information:
> >
> >
>
http://www.ceramics.org/potterscouncil/naturalinstincts/registrationinfo.asp
> >
> > http://www.elizabethpriddy.com
> > http://www.flickr.com/photos/7973282@N03/
> >
> >
> > ----- Original Message ----
> > From: Paul Lewing
> > To: CLAYART@LSV.CERAMICS.ORG
> > Sent: Saturday, May 19, 2007 7:33:59 PM
> > Subject: Re: Porcelain (was worth having)
> >
> >
> > On May 18, 2007, at 10:05 AM, Elizabeth Priddy
> wrote:
> > And they call it porcelain. And it is
> > by some technical standard. But we all know what
> real porcelain
> > is,
> >
> > Actually we don't. One of the first things I
> found out when I was
> > researching my book on china paint was that
> potters, china painters,
> > the dinnerware industry and the tile industry all
> mean different
> > things by the word porcelain. Potters are pretty
> well agreed (more
> > or less) on what they mean by the word, and it
> would be about the
> > definition one would find in something like Hamer
> & Hamer. Even
> > then, some potters think porcelain has to be
> really white; others
> > don't. Some potters think it has to be fired
> above cone 8; others
> > don't. Some potters think it has to be
> translucent; others don't.
> > China painters sometimes refer to stuff fired as
> low as cone 04 as
> > porcelain. A lot of what the dinnerware industry
> calls porcelain
> > potters might call white stoneware. Of the whole
> bunch of them, the
> > tile industry is the only one that has an actual
> quantifiable test
> > for what it porcelain. Their definition says only
> that it must have
> > less than 0.3% water absorbency. No reference to
> firing temperature
> > (although the definition pretty much necessitates
> high temperature)
> > or translucency, or color. You should see what is
> being sold as
> > porcelain tile these days. Almost none of it is
> white, and some of
> > it is as dark brown as chocolate. Is that
> porcelain? It is by their
> > definition.
> > Paul Lewing
> > www.paullewingtile.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.
> >
> >
> >
> >
>
________________________________________________________________________________
> > ____Give spam the boot. Take control with tough
> spam protection in the all-new
> > Yahoo! Mail Beta.
> >
>
http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
> >
> >
>
______________________________________________________________________________
> > 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.
>
Lee Love on sun 20 may 07
There doesn't seem to be any question about what porcelain is amongst
folks who are serious about the subject. There are some variations
on the original Chinese, but they are not difficult for anyone to
follow.
I like porcelain as a base for certain glazes, like chuns.
They show off color really well.
Each medium has its own qualities. If you know your
materials well, then you know how to use them to their best advantage.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
John Rodgers on sun 20 may 07
Elizabeth,
You are quite right - there are many loose definitions of what porcelain
is - and is not. And technically there are the specific chemical
descriptions of each of it's components which together describe a
porcelainous material . But even so, it gets down to whether a given mix
of materials, when fired, meets certain criteria. In my own research of
porcelain over the last 20 years, the best description of porcelain I
have been able to find is this:
TRUE porcelain is white (read bright), hard, vitreous, translucent,
sonorous and fires to vitrification at cone 6 or above.
Note there are no technical specifics in this definition, only
descriptive terminology.
If a clay mix has these qualities, then whatever it's composition, it
can be considered a true porcelain.
So far as I can tell in my years of working with clay, the only people I
know whose working material meets this description are the slip casters.
I throw pottery and I slip cast, mostly for figurines, but some few
vessels. The throwing porcelains I have used is never translucent. The
slip casting porcelain always is. The throwing porcelain is always
sonorous, the slip casting porcelain rarely is - until it is glazed.
So there is no perfection in these matters. Perhaps a true porcelain
does not actually exist. Just some clay bodies come closer than others.
Many beautiful pieces of work are made from slip casting of porcelainous
clay bodies. Often slip casting is the only way to arrive at some
finished works. And for some works, only slip cast porcelain will give
the desired finished results.
Yesterday, I sold a number of sets of chalices and plates. The chalice
was my design and slip cast. The plate was my design and wheel thrown.
The pieces were mates - matching patterns, colors, etc. The only way to
derive these matching pieces was to slip cast one, throw the other.
Given the heated debate of "handmade" vs "other" - it would be really
interesting to see how this set would be handled in offered up for show
entry. The set would certainly create a dilemma of 'half and harf".
Would the set be totally acceptable, totally rejected, or split by the
nature of the making of each piece?
Truth be told, my sale of the chalice and plate set was the result of
the story behind it, not how it was made, though how it was made was
included. It was the tale of designs of African origins, missionaries to
the Congo, lightning strikes, etc, all related to the work, plus the
visual appeal of the pieces, all together that made the sale.
Only a few people ever get hung up on the handmade vs other in their buying.
As for porcelain, most of the time I see throwing porcelain as something
very different from my porcelain casting slip. It is handled
differently, and applied differently. I use throwing porcelain in my
pottery work. I use slip cast porcelain principly in my figurine work,
though on some occasions one does wander of into the realm of the other.
Regards,
John Rodgers
Chelsea, AL
Elizabeth Priddy wrote:
> Well, there you have it!
>
> This is a pretty good demonstration that there are as many
> loose definitions of porcelain in the ceramic world as there
> are "hand-made" in the marketed wares world.
>
> And why would a term that ought to have a solid definition
> be in such a grey area? Because a lot of people want what
> they are doing to be porcelain and no industry standard to
> go by, except those tile people.
>
> I consider porcelain very high fired translucent clay with
> virtually no inclusions making for a pure white clay body.
>
> But that is just me, apparently !
>
> Thanks for that information.
>
> Elizabeth Priddy
> Beaufort, NC - USA
>
> Natural Instincts Conference Registration Information:
>
> http://www.ceramics.org/potterscouncil/naturalinstincts/registrationinfo.asp
>
> http://www.elizabethpriddy.com
> http://www.flickr.com/photos/7973282@N03/
>
>
> ----- Original Message ----
> From: Paul Lewing
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Saturday, May 19, 2007 7:33:59 PM
> Subject: Re: Porcelain (was worth having)
>
>
> On May 18, 2007, at 10:05 AM, Elizabeth Priddy wrote:
> And they call it porcelain. And it is
> by some technical standard. But we all know what real porcelain
> is,
>
> Actually we don't. One of the first things I found out when I was
> researching my book on china paint was that potters, china painters,
> the dinnerware industry and the tile industry all mean different
> things by the word porcelain. Potters are pretty well agreed (more
> or less) on what they mean by the word, and it would be about the
> definition one would find in something like Hamer & Hamer. Even
> then, some potters think porcelain has to be really white; others
> don't. Some potters think it has to be fired above cone 8; others
> don't. Some potters think it has to be translucent; others don't.
> China painters sometimes refer to stuff fired as low as cone 04 as
> porcelain. A lot of what the dinnerware industry calls porcelain
> potters might call white stoneware. Of the whole bunch of them, the
> tile industry is the only one that has an actual quantifiable test
> for what it porcelain. Their definition says only that it must have
> less than 0.3% water absorbency. No reference to firing temperature
> (although the definition pretty much necessitates high temperature)
> or translucency, or color. You should see what is being sold as
> porcelain tile these days. Almost none of it is white, and some of
> it is as dark brown as chocolate. Is that porcelain? It is by their
> definition.
> Paul Lewing
> www.paullewingtile.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.
>
>
>
> ____________________________________________________________________________________Give spam the boot. Take control with tough spam protection in the all-new Yahoo! Mail Beta.
> http://advision.webevents.yahoo.com/mailbeta/newmail_html.html
>
> ______________________________________________________________________________
> 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.
>
>
>
Elizabeth Priddy on sun 20 may 07
I honestly don't know the answer to your
question. I wish there was an industrial
standard for this real world hard fact item.
It shouldn't be vague, like hand-made.
I like David Beumee's definitions and descriptions,
as they agree with my own.
http://www.davidbeumee.com/studio.htm
But they are aesthetic definitions, not technical.
And yes, as someone pointed out, my mind is
made up about what porcelain is. My inability to
describe it to a molecular "T", is something that
I can sleep soundly knowing. I know it when I
touch it.
I am not much of a purist, as I think you can make
your own rules and do your own thing. But words
need to mean things and technical terms need to
be technical, not a feeling.
So I will leave that one for the techs.
Elizabeth Priddy
Beaufort, NC - USA
Natural Instincts Conference Registration Information:
http://www.ceramics.org/potterscouncil/naturalinstincts/registrationinfo.asp
http://www.elizabethpriddy.com
http://www.flickr.com/photos/7973282@N03/
----- Original Message ----
From: Michael Wendt wendtpot@LEWISTON.COM
Whiteness is a quality that
can actually be measured.
Light transmission per cross-
section can also be measured.
Absorption can be measured.
If you are willing to define the
parameters tightly enough, only
a few clay formulations will meet
all of the criteria to be called
porcelain.
...If you set the standard that high would
GE 84 porcelain no longer be porcelain?
Just asking.
Regards,
Michael Wendt
@pclink.com.
____________________________________________________________________________________Sick sense of humor? Visit Yahoo! TV's
Comedy with an Edge to see what's on, when.
http://tv.yahoo.com/collections/222
David Beumee on sun 20 may 07
A most interesting comment Michael. I am hoping the price of GE 84 or GE 90 Helmer is not overly prohibitive, because Helmer has a degree of plasticity and workability that almost no other kaolin has, with the exception of Tile #6. It would be such a pleasure to produce a Rocky Mountain porcelain body, particularly if the spar (and possibly silica?) you have been mining and refining could be incorporated as well. Hundred mesh Helmer is a great kaolin, but doesn't burn white enough for my taste. It throws great though, especially in combination with EPK. Thanks for working on refining your excellent product, and please keep us all posted.
David Beumee
Porcelain by David Beumee
www.davidbeumee.com
Lafayette, CO
-------------- Original message ----------------------
From: Michael Wendt
>
> Elizabeth,
> I will agree with your definition with
> one proviso:
> The whiteness standard needs to be
> set at a fairly high level.
> What whiteness do you recommend?
> GE 84?
> GE 87?
> GE 90?
> Whiteness is a quality that
> can actually be measured.
> Light transmission per cross-
> section can also be measured.
> Absorption can be measured.
> It's odd though that unlike
> the term "hand made" which
> can be observed directly by
> inspection, the characteristics
> of a porcelain require extensive
> tests to quantify its characteristics
> and those test results always
> fall on a continuum of values.
> If you are willing to define the
> parameters tightly enough, only
> a few clay formulations will meet
> all of the criteria to be called
> porcelain.
> Recent research with Helmer Kaolin
> has found a way to remove enough
> of the iron-titanium contaminant to
> get a GE90 + fired color if people
> were willing to pay the price for it.
> If you set the standard that high would
> GE 84 porcelain no longer be porcelain?
> Just asking.
> Regards,
> Michael Wendt
> Wendt Pottery
> 2729 Clearwater Ave
> Lewiston, ID 83501
> USA
> 208-746-3724
> http://www.wendtpottery.com
> wendtpot@lewiston.com
> Elizabeth wrote:
> I consider porcelain very high fired translucent clay
> with
> virtually no inclusions making for a pure white clay
> body.
>
> But that is just me, apparently !
>
> Thanks for that information.
>
> Elizabeth Priddy
> Beaufort, NC - USA
>
> ______________________________________________________________________________
> 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.
Lois Ruben Aronow on sun 20 may 07
I always love statements and definitions that agree with my own.
..Lo
>
> I like David Beumee's definitions and descriptions, as they
> agree with my own.
> http://www.davidbeumee.com/studio.htm
>
> But they are aesthetic definitions, not technical.
>
Ivor and Olive Lewis on mon 21 may 07
Dear Charles Hightower,=20
I think you expose a flaw in thinking with your comment ".... one could =
throw the rim of a bowl thin enough to be translucent and the rest not. =
Is the rim porcelain and the rest white stoneware?"
As described, it would be possible for the interior of the thicker clay =
to be under mature, hence opaque due to changes in refractive index at =
particle interfaces, especially where there were open voids.
Fully matured clay, compounded as a porcelain from siliceous, =
kaolinitic, felspathic ingredients, if sliced into thin sections which =
could be penetrated by light, would exhibit observable and measurable =
translucency.
If refractive index was uniform throughout the fired clay you would have =
a transparent fabric.
Now, Black Porcelain. There is a seemingly contradiction in terms ! !
| |
|
