Ceramic Design Group on sun 8 may 05
Hi Ron:
I appreciate the dialog from all sides on this subject. However, I am
finding that there are some issues that both semantically and
contextually that I am sure not only I but many of the readers on the
list are finding perhaps a bit confusing.
What I had understood and I am sure many others the same is that the
standards apply to clays. I have reviewed many of the posts on this
thread and this is indeed the common "thread" in all of them. Now I
read that "I was not suggesting that the mines provide standard clays
- of course there will always be differences." So now we do indeed
have a "baseline" and that baseline is that everything will be
different from lot to lot and from bag to bag. So here is a difference
of opinion. If everything is different, then how can we develop a
standard? Obviously we can't. Remember the talk some years ago about a
"Clayart Claybody" ? I had hoped I would not have to bring this bad
idea up again now. This was one of the most poorly thought out and
poorly conceived ideas that I have ever heard. I am glad it went away
by its own attrition and lack of really good thinking and judgement. I
remember the phrase/statement/assertion:
"We will have our own claybody.....(."left blank intenionally" )will
provide the recipie and( "left blank intenionally" )will make it and
("left blank intentionally") will test it." There was a certain degree
of pompousness when this came out on the list and I for one had a
pretty good chuckle over this one for sure.
To me this was a low point on the history of this list. A Clayart
Claybody? How funny. What was more than funny was the seriousness on
how it was taken as gospel by many on this list.
So if we establish a baseline that everything is diffferent, then there
can't be a standard. This is a conundrum within a conundrum and a
philosophical non-sequitor, The analysis sheets that you still can
receive from clay mines and materials producers, from clay companies
that blend bodies are relative only to a point in time, a particular
shipment, and will vary to some small degree. And they won't tell you
what is in the bag. The phrase "representative analysis" is key, and
that is exactly what the sheets from the suppliers are. Perhaps that
shipment of Newman is higher in iron than the previous one, or the ball
clay has a greater percentage of silica or was full of lignite.
All is relative and we take it on faith. The weak link in the
discussion of standards is the clay itself. You can provide a standard
of a particular mixed batch for absorption and shrinkage and you can
DTA it to see its expansion and contraction. But other than that, the
stuff from the mine is the weak link.
I have worked with Newman Red for many years. It reminds me of the old
Valentine PBX clay from AP Green years ago. In any of the bodies I have
mixed whether it be a casting body or a plastic body it was was either
wet screened or dry screened. I also remember when AP Green Dry Milled
28 mesh Fireclay was around. I sieved that also, and Hawthorne. The
amount of junk on the screen, the LOI, is amazing. Same with Old Mine 4
Ball clay. Mix some of that as a slurry and pass it through a 40 or 50
mesh screen. Lots of junk. That's why the stuff in the bag is the weak
link and always will be.
I would certainly place more value in an analysis of Feldspar or Flint
than I would with a clay that's for sure. You can check raw materials
for their crystalline structure via x-ray diffraction and see if that
sample shows the same peaks and valleys that the previous shipment
does. You can dillatometer a clay body and see what the critical points
are and see if there is any free silica showing up at the end. And all
of these tests, as thorough as they are and whatever value is that the
data provides is only relative to what you do with it. You can
certainly assert that whatever claybody you make and sell ,according to
these afformentioned tests has "x" absorption, "x" shrinkage and has
whatever cone range you think it might have. Thats all you can do. You
provide the information to the end user only as "insurance" and as
comforting the "liability" issues that might be involved. The idea that
it will be used in certain perceived "correctness" is I think, at best,
a folly.
And all you can do is again, provide that as information. You have no
standard for how these materials will perform in a potters studio and
what conditions they will be used. So standards are only useful, if
there were to be any, at the point of blending at Tuckers or Laguna, or
where ever. You put these forward in good faith to the best of your
ability but you don't and won't know how they will bused and in what
conditions. Therein is the problem with "standards" both in context as
well as with the semantics of them.
Standards/methodology for testing raw materials, yes there are some.
Standards/methodology for testing a mixed clay body, yes there are
some. But what do you compare the results to? A true representative
sample? No such thing. Standards for ascertaining what a certain
material "should be," again, no such thing. How many times have you
seen lime contamination in coarse Fireclays?
Even a company as big as Laguna has little, if any, "clout" with the
mines. This is just plain nonsense. We represent such a small
percentage of the endusers of these materials that the idea of having
clout is more humorous than anything else. Most of the kaolin goes to
the paper and to the cosmetic industries, not into ceramics.
If you have followed my posts and writings for many years I have urged
potters to take responsibility for their clay bodies. There is a rather
long discourse on the Digitalfire site entitled "The Whining Stops
Here...Taking Responsibility for your Claybody" that I authored years
ago. Your book goes a long way to further the idea of responsibility
with glazes, But if the glazes sit on an inferior clay body, then it
makes not difference if the glaze is balanced or not. The point is if
that the claybody is poorly compounded its garbage in and garbage out.
Fortunately clay companies like Tuckers, Laguna, etc take the time to
test the raw materials. But most of them do not and many of them don't
even screen coarse clays. But the limitations of these tests are fairly
obvious and anyone with a some knowledge of raw materials will indeed
tell you that they are only as good as what the tests are and relative
only to a particular time and place, in this case, to a batch that runs
through the plant at a particular time. Once its out the door, its open
season. That's why the "limits of liability" for the clay body that is
in the box that you print on the box in bold type is there. That's
because you don't know how it will be used. That's because there are no
standards and why these companies protect themselves with "limits of
liability".....we will replace the material but not the finished ware.
That about summarizes to me, any idea of standards.
We take it on faith that our pots don't leak and our glazes won't
deteriorate. I am willing to posit that most potters out there wouldn't
know how to test for shrink and absorption let alone do a vinegar test
on their stuff. Or if they have the ability to blend their own clay
send a sample out for a DTA. There is no control, therefore their can
be no standard.
I would also wonder about how you could make these "perceived
standards" more common. I would suggest that you can't. Its a matter
of faith. I take it on faith that my stock of Greenstripe, Ti21 Ball
Clay, Foundry Hill Creme, FC340, Flint, Spar, Mulcoa, and many other
materials is fine. I blend it and test for shrink and absorption, have
a DTA run, and when I was making useable ware, tested our glazes for
proper fit on the ware. That's all a potter can do. You can't make
'standards" more common because there are no standards. A DTA test is a
"standard" test. So is testing for shrinkage and absorption. The acid
test with lemon juice is kind of a standard. But what is the acid
percentage of the lemon wedge and for how long does it remain on the
ware? Provide a standard percentage and a determined time of contact,
then you have a standard test.
I would also question the " you can get a pretty good idea by looking
at the fired clay - especially when there is iron present. It is an
excellent way to help diagnose problems." Yes the fired clay can
provide visual clues as to what has happened in the kiln. But a "pretty
good idea" is not quantifiable. It does not tell me anything. And
that's because most potters fire by the seat of their pants and have no
idea of what is going on let alone how to even measure it, even as
vague as those measurements are. Again, here are differences in
semantics and context. Ask a potter how much reduction they get or how
good the combustion is to get whatever degree of reduction they want
and its met with a blank stare in most cases " uh, I see some back
pressure and it smells like ass" Now that's a standard I could
certainly get behind and agree with!?
If you need standards, then perhaps we need to have firing standards
because I don't care if you have the most perfect blended pure clays in
your claybodies and the most stable and properly formulated glazes
siting on that perfect clay body in the all perfect ceramics world, if
you fire it wrong, you negate all the perfect stuff that you put into
it to get there. And you get ware that if over-reduced is brittle and
defective. The list goes on and on.
Standards are only as good as what you perceive them as being even if
you could find a way to develop them. That's the problem because you
really can't. Clay and glaze technology as applied to the potter's art
and craft is like the basis for religion, taken on faith.
I'll be the first provide a "huzzah" when I see a list of quantifiable
"standards" from the beneficent and omniscient pottery police. Let me
know when that happens.
I commend the few clay companies for doing proper testing and for the
work that you do to help potters with their glazes and helping them to
see the importance of proper glaze fit. I think we disagree on some of
the basics but we do have some commonality on the necessity for taking
responsibility.
Respectfully,
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
Plant location for commercial deliveries excluding USPS
1280 13th Street Suite K
Steamboat Springs CO 80487
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
> Hi Jonathan,
>
> I was not suggesting that the mines provide standard clays - of course
> there will always be differences - The Feldspar Corporation used to
> send an
> analysis with each shipment. That could be a standard - and if we had
> some
> clout with the mines we could insist.
>
> I was talking about taking responsibility for what we make particularly
> with functional pots - apply some standards - pots that don't leak -
> clay
> that does not leak when fired to the advertised temperature - glazes
> that
> don't deteriorate with use.
>
> We would all be better off if those standards were more common.
>
> I simply stated that we test every batch of the Newman Red at cone 10
> - in
> oxidation and reduction - and it works under both conditions - some one
> said a high iron body could not be serviceable in both oxidation and
> reduction - I am simply saying - it depends on the formulation - and
> it can
> be done.
>
> As for telling if a body is reduced or not and all the variables in
> between
> - you can get a pretty good idea by looking at the fired clay -
> especially
> when there is iron present. It is an excellent way to help diagnose
> problems.
>
> Newman is a refractory high iron bearing clay - it has more iron in it
> than
> Red Art for instance.
>
> If you are going to use it you must sieve it - it is one of our more
> interesting unrefined clays -.
>
> RR
>
>
>> I don't know how we can have standards with materials that are formed
>> in the earth and then processed for industry. They are not
>> beneficiated
>> by any clay manufacturing company I know of. The extent of
>> beneficiation that I have seen is screening coarse fireclays, and it
>> still leaves problems. I only know of a few potters that wet mix to a
>> slurry, Sweco the mix, filter press it and then pug mill it. Then and
>> only then can there even be some degree of standards. Heck, clay body
>> mfgs have different penetrometers with different scales so you can't
>> use any numbers to base moisture content from supplier to supplier.I
>> think to have standards for clay bodies is an effort wrought with
>> problems because it is impossible to have a standard from which to
>> have
>> a baseline. Provide a baseline and I might think differently. But what
>> baseline and how do you quantify it?
>>
>> I also question what is full reduction, some or no reduction? The only
>> way to quantify this is with proper stochiometric combustion equipment
>> and an oxygen probe. Most potters I know still fire by the seat of
>> their pants, at best.
>>
>> I have used Newman Red in casting bodies and found that after sieving
>> it to get all the junk out it is a pretty good material to add to a
>> clay. I don't know about all the different atmostpheres though, and I
>> would posit that it does have a very low iron content. I don't have
>> my
>> data sheet as I am traveling, but I would think that it is pretty low
>> so it might impart little actual iron thus not acting to provide any
>> fluxing action (As Redart does) but just enough color the body. Just
>> my
>> opinion.
>> Jonathan
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
> Phone: 613-475-9544
> Fax: 613-475-3513
>
> _______________________________________________________________________
> _______
> 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.
>
Jonathan Kaplan on fri 13 may 05
Hi John:
Thanks for your comments and adding to this very interesting and
provocotive discussion.
I don't think anyone has been flying off the handle. I think what
happened is that there was a misunderstanding that was basically
semantics or etymology or what ever. Annie and I both understand full
well what Ron is saying and in no way are we ganging up on him. We were
not the only ones on the list to notice that there was a
misunderstanding. No one has ever questioned or disrespected his wealth
of knowledge or his efforts, contributions to ceramics, and work for
potters and for Tucker.
What i have learned from being on the clayart list since its inception
is that you have to be very clear as to what you say and to make sure
you use the correct words, the correct phrases and make sure that you
are knowledgeable about the subject at hand. I think in this case, Ron
was just not clear and that's all.
And its important that these posts or any posts not be taken
personally. Its important not to snipe or to be disrespectful. We all
have done it and its important that we proof-read out posts before
sending that email don't you think?
None of us said that quality plastic clay bodies cannot be mass
produced.
My last post said exactly what you say here. Blended clay bodies have
"requirements" . These are exactly what you say and what I said. I
think that the word "requirement" might be a better choice of
words....for instance here is a hypothetical blended clay body from a
hypothetical clay comany
*****************************
CLAY BODY NAME "Big Butt White Stoneware" cone 9-10
BATCH DATE 05/13/05
BATCH SIZE 10 TONS 20,000 POUNDS DRY WEIGHT
TOTAL WET BATCH 24,000 POUNDS (20 % water)
PENETROMETER READING ("PIGSTICKER") 4.2
CLAY BODY DESCRIPTION A smooth white stoneware vitireous at cone 9-10,
no iron specking. Comprised of airfloated white burning kaolins, light
burning ball clays, screened 50M Fireclay, fine mesh refractory
calcine "grog" type material, contains pyrophyllite.
FIRING: Excellent light grey to white in oxidation more grey in
reduction with oxyprobe at 6.5-7.0 at cone 10 flat
SHRINKAGE TARGET REQUIREMENT: 11% CURRENT BATCH 10.5%
ABSORPTION TARGET REQUIREMENT: 2% CURRENT BATCH 1.9%
CURRENT DTA TESTS-NO CRYSTOBALLITE AT PEAK
ALL QUARTZ INVERSIONS WITHIN NORMAL RANGE
ALL DTA PLOTS FOR THIS BATCH ARE AVAILABLE IF REQUESTED BY SNAIL MAIL
OR CAN BE VIEWED ON LINE AT
www.bullshit.com
***********************************************************
Would this not be more proactive and better?
Further, I know some mfgs that don't screen coarse mesh materials. I
know manufacturers that don't test materials and don't have a lab.
Further I also know mfg's that have no idea of what a DTA is or care.
Every clay body manufacturer takes a huge risk in making clay. Even a
bigger risk when testing is not done. I am just lucky that I can do it
myself and the risk is mine.
If there were a cost effective way to mass produce this by wet blending
as a slip, screening, dewatering with a filter press, then miixing in
a muller or pre-pug and then deairing it through a deairing
pug/extruder, all the prepared bodies done this way would be better. It
can't be done.
Potter's finding those companies making highly variable clay bodies
need to look seriously at finding other suppliers who do produce a
quality bodies that have been properly tested, the raw materials that
go into them and the bodies that are made from those raw materials.
In no way do I think that Annie, Jon, or myself ever suggested that
Ron's methodology was at all incorrect or anything close. Nor do I
think we were ever questioning the quality of his work. I think we just
disagreed on a choice of words and that's it.
Respectfully,
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
(please use this address for all USPS deliveries)
Plant Location:
1280 13th Street Suite K
Steamboat Springs CO 80487
(please use this address for all UPS, courier, and common carrier
deliveries only!!)
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
Edouard Bastarache Inc. on fri 13 may 05
Hello all,
what about the little guy who is making his own clays
not having access to all the sophisticated analyses?
Is he a worse artist-potter?
Are his pots crap?
Later,
"Ils sont fous ces quebecois"
"They are insane these quebekers"
"Estαn locos estos quebequeses"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
----- Original Message -----
From: "John Hesselberth"
To:
Sent: Friday, May 13, 2005 7:35 PM
Subject: Re: T2 clay & carbon core now STANDARDS, long.......
> On Friday, May 13, 2005, at 03:55 PM, Annie Chrietzberg wrote:
>
>> The idea that the materials that we use are stable just isn't
>> realistic.
>
> Annie, Jon, Jonathan,
>
> I get the feeling you are having so much fun ganging up on Ron that you
> aren't even trying to understand what we is saying. He never said or
> implied the above, although he did say some materials are more
> reliable/stable than others and one might want to favor using those
> were possible.
>
> What he did say is that clay bodies can be made to a standard, i.e.
> they have the same shrinkage and absorption at a given cone, be free of
> garbage, etc. It requires analyzing the materials as they come in,
> adjusting the recipes on an ongoing basis, and taking care in the
> screening and mixing of the body to produce a consistent clay body that
> a potter can trust to be the same over time. The quality clay body
> suppliers are doing this today. We know it can be done and those who
> say it can't are just making excuses for a shoddy operation. There are
> also a number of suppliers making highly variable bodies that potters
> find very frustrating. Ideally the market will drive those poor quality
> suppliers out of business but, unfortunately, it doesn't seem to happen.
>
> Now please, if you are going to continue this discussion try to
> understand what each other is saying before flying off the handle.
>
> Regards,
>
> John
>
> ______________________________________________________________________________
> 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.
>
>
Ron Roy on fri 13 may 05
Hi Jonathan,
Long post - I tend to put off answering them - especially those with so
many different ideas.
I have decided to concentrate on the one aspect that I think is important.
When you mix clays for potters - you need to try and provide some
consistency from batch to batch.
We know the raw materials vary so how do we address that problem?
If we know what absorbency is ideal for what the clay is going to be used
for - we can make adjustments to future batches to keep the clay looking
and acting the same. When we do this we are applying standards.
If we were using variable materials to make glazes we would need to apply
some methodology to limit the variations due to those variations.
What emerges from a program of testing - both manufactures bodies and raw
materials is data from which you can set up your own standards - same with
durable glazes.
During the testing of raw materials it becomes obvious which raw materials
are the most variable - and which are most stable.
It is then possible - when reformulating - to counter the effect of raw
materials - to use more stable materials when appropriate.
In the end - over years - this can result is much more stable clays - that
need less and less adjusting.
By the way - what is your relationship to Laguna Clays?
I noticed a while ago you said you did not buy clay from clay companies
anymore - I assumed you had some bad experiences with bought clay bodies?
RR
>I appreciate the dialog from all sides on this subject. However, I am
>finding that there are some issues that both semantically and
>contextually that I am sure not only I but many of the readers on the
>list are finding perhaps a bit confusing.
>
>What I had understood and I am sure many others the same is that the
>standards apply to clays. I have reviewed many of the posts on this
>thread and this is indeed the common "thread" in all of them. Now I
>read that "I was not suggesting that the mines provide standard clays
>- of course there will always be differences." So now we do indeed
>have a "baseline" and that baseline is that everything will be
>different from lot to lot and from bag to bag. So here is a difference
>of opinion. If everything is different, then how can we develop a
>standard? Obviously we can't. Remember the talk some years ago about a
>"Clayart Claybody" ? I had hoped I would not have to bring this bad
>idea up again now. This was one of the most poorly thought out and
>poorly conceived ideas that I have ever heard. I am glad it went away
>by its own attrition and lack of really good thinking and judgement. I
>remember the phrase/statement/assertion:
>
>"We will have our own claybody.....(."left blank intenionally" )will
>provide the recipie and( "left blank intenionally" )will make it and
>("left blank intentionally") will test it." There was a certain degree
>of pompousness when this came out on the list and I for one had a
>pretty good chuckle over this one for sure.
>To me this was a low point on the history of this list. A Clayart
>Claybody? How funny. What was more than funny was the seriousness on
>how it was taken as gospel by many on this list.
>
>So if we establish a baseline that everything is diffferent, then there
>can't be a standard. This is a conundrum within a conundrum and a
>philosophical non-sequitor, The analysis sheets that you still can
>receive from clay mines and materials producers, from clay companies
>that blend bodies are relative only to a point in time, a particular
>shipment, and will vary to some small degree. And they won't tell you
>what is in the bag. The phrase "representative analysis" is key, and
>that is exactly what the sheets from the suppliers are. Perhaps that
>shipment of Newman is higher in iron than the previous one, or the ball
>clay has a greater percentage of silica or was full of lignite.
>
> All is relative and we take it on faith. The weak link in the
>discussion of standards is the clay itself. You can provide a standard
>of a particular mixed batch for absorption and shrinkage and you can
>DTA it to see its expansion and contraction. But other than that, the
>stuff from the mine is the weak link.
>
>I have worked with Newman Red for many years. It reminds me of the old
>Valentine PBX clay from AP Green years ago. In any of the bodies I have
>mixed whether it be a casting body or a plastic body it was was either
>wet screened or dry screened. I also remember when AP Green Dry Milled
>28 mesh Fireclay was around. I sieved that also, and Hawthorne. The
>amount of junk on the screen, the LOI, is amazing. Same with Old Mine 4
>Ball clay. Mix some of that as a slurry and pass it through a 40 or 50
>mesh screen. Lots of junk. That's why the stuff in the bag is the weak
>link and always will be.
>
>I would certainly place more value in an analysis of Feldspar or Flint
>than I would with a clay that's for sure. You can check raw materials
>for their crystalline structure via x-ray diffraction and see if that
>sample shows the same peaks and valleys that the previous shipment
>does. You can dillatometer a clay body and see what the critical points
>are and see if there is any free silica showing up at the end. And all
>of these tests, as thorough as they are and whatever value is that the
>data provides is only relative to what you do with it. You can
>certainly assert that whatever claybody you make and sell ,according to
>these afformentioned tests has "x" absorption, "x" shrinkage and has
>whatever cone range you think it might have. Thats all you can do. You
>provide the information to the end user only as "insurance" and as
>comforting the "liability" issues that might be involved. The idea that
>it will be used in certain perceived "correctness" is I think, at best,
>a folly.
>
>And all you can do is again, provide that as information. You have no
>standard for how these materials will perform in a potters studio and
>what conditions they will be used. So standards are only useful, if
>there were to be any, at the point of blending at Tuckers or Laguna, or
>where ever. You put these forward in good faith to the best of your
>ability but you don't and won't know how they will bused and in what
>conditions. Therein is the problem with "standards" both in context as
>well as with the semantics of them.
>
>Standards/methodology for testing raw materials, yes there are some.
>Standards/methodology for testing a mixed clay body, yes there are
>some. But what do you compare the results to? A true representative
>sample? No such thing. Standards for ascertaining what a certain
>material "should be," again, no such thing. How many times have you
>seen lime contamination in coarse Fireclays?
>
>Even a company as big as Laguna has little, if any, "clout" with the
>mines. This is just plain nonsense. We represent such a small
>percentage of the endusers of these materials that the idea of having
>clout is more humorous than anything else. Most of the kaolin goes to
>the paper and to the cosmetic industries, not into ceramics.
>
>If you have followed my posts and writings for many years I have urged
>potters to take responsibility for their clay bodies. There is a rather
>long discourse on the Digitalfire site entitled "The Whining Stops
>Here...Taking Responsibility for your Claybody" that I authored years
>ago. Your book goes a long way to further the idea of responsibility
>with glazes, But if the glazes sit on an inferior clay body, then it
>makes not difference if the glaze is balanced or not. The point is if
>that the claybody is poorly compounded its garbage in and garbage out.
>Fortunately clay companies like Tuckers, Laguna, etc take the time to
>test the raw materials. But most of them do not and many of them don't
>even screen coarse clays. But the limitations of these tests are fairly
>obvious and anyone with a some knowledge of raw materials will indeed
>tell you that they are only as good as what the tests are and relative
>only to a particular time and place, in this case, to a batch that runs
>through the plant at a particular time. Once its out the door, its open
>season. That's why the "limits of liability" for the clay body that is
>in the box that you print on the box in bold type is there. That's
>because you don't know how it will be used. That's because there are no
>standards and why these companies protect themselves with "limits of
>liability".....we will replace the material but not the finished ware.
>That about summarizes to me, any idea of standards.
>
>We take it on faith that our pots don't leak and our glazes won't
>deteriorate. I am willing to posit that most potters out there wouldn't
>know how to test for shrink and absorption let alone do a vinegar test
>on their stuff. Or if they have the ability to blend their own clay
>send a sample out for a DTA. There is no control, therefore their can
>be no standard.
>
>I would also wonder about how you could make these "perceived
>standards" more common. I would suggest that you can't. Its a matter
>of faith. I take it on faith that my stock of Greenstripe, Ti21 Ball
>Clay, Foundry Hill Creme, FC340, Flint, Spar, Mulcoa, and many other
>materials is fine. I blend it and test for shrink and absorption, have
>a DTA run, and when I was making useable ware, tested our glazes for
>proper fit on the ware. That's all a potter can do. You can't make
>'standards" more common because there are no standards. A DTA test is a
>"standard" test. So is testing for shrinkage and absorption. The acid
>test with lemon juice is kind of a standard. But what is the acid
>percentage of the lemon wedge and for how long does it remain on the
>ware? Provide a standard percentage and a determined time of contact,
>then you have a standard test.
>
>I would also question the " you can get a pretty good idea by looking
>at the fired clay - especially when there is iron present. It is an
>excellent way to help diagnose problems." Yes the fired clay can
>provide visual clues as to what has happened in the kiln. But a "pretty
>good idea" is not quantifiable. It does not tell me anything. And
>that's because most potters fire by the seat of their pants and have no
>idea of what is going on let alone how to even measure it, even as
>vague as those measurements are. Again, here are differences in
>semantics and context. Ask a potter how much reduction they get or how
>good the combustion is to get whatever degree of reduction they want
>and its met with a blank stare in most cases " uh, I see some back
>pressure and it smells like ass" Now that's a standard I could
>certainly get behind and agree with!?
>
>If you need standards, then perhaps we need to have firing standards
>because I don't care if you have the most perfect blended pure clays in
>your claybodies and the most stable and properly formulated glazes
>siting on that perfect clay body in the all perfect ceramics world, if
>you fire it wrong, you negate all the perfect stuff that you put into
>it to get there. And you get ware that if over-reduced is brittle and
>defective. The list goes on and on.
>
>Standards are only as good as what you perceive them as being even if
>you could find a way to develop them. That's the problem because you
>really can't. Clay and glaze technology as applied to the potter's art
>and craft is like the basis for religion, taken on faith.
>
>I'll be the first provide a "huzzah" when I see a list of quantifiable
>"standards" from the beneficent and omniscient pottery police. Let me
>know when that happens.
>
>I commend the few clay companies for doing proper testing and for the
>work that you do to help potters with their glazes and helping them to
>see the importance of proper glaze fit. I think we disagree on some of
>the basics but we do have some commonality on the necessity for taking
>responsibility.
>
>Respectfully,
>
>
>Jonathan
>
>
>Jonathan Kaplan
>Ceramic Design Group
>PO Box 775112
>Steamboat Springs CO 80477
>(970) 879-9139
>
>Plant location for commercial deliveries excluding USPS
>1280 13th Street Suite K
>Steamboat Springs CO 80487
>
>info@ceramicdesigngroup.net
>www.ceramicdesigngroup.net
>
>
>
>> Hi Jonathan,
>>
>> I was not suggesting that the mines provide standard clays - of course
>> there will always be differences - The Feldspar Corporation used to
>> send an
>> analysis with each shipment. That could be a standard - and if we had
>> some
>> clout with the mines we could insist.
>>
>> I was talking about taking responsibility for what we make particularly
>> with functional pots - apply some standards - pots that don't leak -
>> clay
>> that does not leak when fired to the advertised temperature - glazes
>> that
>> don't deteriorate with use.
>>
>> We would all be better off if those standards were more common.
>>
>> I simply stated that we test every batch of the Newman Red at cone 10
>> - in
>> oxidation and reduction - and it works under both conditions - some one
>> said a high iron body could not be serviceable in both oxidation and
>> reduction - I am simply saying - it depends on the formulation - and
>> it can
>> be done.
>>
>> As for telling if a body is reduced or not and all the variables in
>> between
>> - you can get a pretty good idea by looking at the fired clay -
>> especially
>> when there is iron present. It is an excellent way to help diagnose
>> problems.
>>
>> Newman is a refractory high iron bearing clay - it has more iron in it
>> than
>> Red Art for instance.
>>
>> If you are going to use it you must sieve it - it is one of our more
>> interesting unrefined clays -.
>>
>> RR
>>
>>
>>> I don't know how we can have standards with materials that are formed
>>> in the earth and then processed for industry. They are not
>>> beneficiated
>>> by any clay manufacturing company I know of. The extent of
>>> beneficiation that I have seen is screening coarse fireclays, and it
>>> still leaves problems. I only know of a few potters that wet mix to a
>>> slurry, Sweco the mix, filter press it and then pug mill it. Then and
>>> only then can there even be some degree of standards. Heck, clay body
>>> mfgs have different penetrometers with different scales so you can't
>>> use any numbers to base moisture content from supplier to supplier.I
>>> think to have standards for clay bodies is an effort wrought with
>>> problems because it is impossible to have a standard from which to
>>> have
>>> a baseline. Provide a baseline and I might think differently. But what
>>> baseline and how do you quantify it?
>>>
>>> I also question what is full reduction, some or no reduction? The only
>>> way to quantify this is with proper stochiometric combustion equipment
>>> and an oxygen probe. Most potters I know still fire by the seat of
>>> their pants, at best.
>>>
>>> I have used Newman Red in casting bodies and found that after sieving
>>> it to get all the junk out it is a pretty good material to add to a
>>> clay. I don't know about all the different atmostpheres though, and I
>>> would posit that it does have a very low iron content. I don't have
>>> my
>>> data sheet as I am traveling, but I would think that it is pretty low
>>> so it might impart little actual iron thus not acting to provide any
>>> fluxing action (As Redart does) but just enough color the body. Just
>>> my
>>> opinion.
>>> Jonathan
>>
>> Ron Roy
>> RR#4
>> 15084 Little Lake Road
>> Brighton, Ontario
>> Canada
>> K0K 1H0
>> Phone: 613-475-9544
>> Fax: 613-475-3513
>>
>> _______________________________________________________________________
>> _______
>> 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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Annie Chrietzberg on fri 13 may 05
Ron, dude,
The idea that the materials that we use are stable just isn't
realistic. Even those materials that are similar from batch to batch
will change over the years as the mining process moves deeper into the
strata. Materials are not laid down in the earth in a consistent form
all the way through.
And you ARE using variable materials to make glaze, unless you are
using only frits and stains, but even those are subject to someone you
can't control mixing them. Mason stains vary in color from batch to
batch.
You seem to think there is some way to control all of the natural
variations in the materials that we use, but there isn't. You and Jon
and Jonathan all agree that the only way to understand what you are
working with, and create standards for what you are using, and how you
are using it, is by testing the materials. There is agreement there.
The disagreement is in the notion of Universal Standards on Materials.
They disagree with you. Get over it.
The disagreement, as I understand it, sprung from an interpretation of
what you were positing about Standards. If it was misunderstood, then
there was a mistake, but I bet alot of people learned something about
the nature of those bags of dust they buy from the discussion. That's
a good thing.
Jonathan's (& my) relationship to Laguna is this - we occasionally buy
equipment and supplies from them. We do not receive a discount, in
case you are wondering. We recently bought a Laguna spray booth and
are pleased as punch with it.
We were on a two week road trip, went to the CCACA conference, went to
San Fran to interview a potter, then went to LA & hung out with Pacini.
We stayed a couple of nights at his house, watched westerns with his
amazing 8 year old son, went out for tacos, drank beer & talked shop,
including this idea you have been positing about standards. We all
agreed that this notion, as we understood it, was misinformation.
Jonathan formulates his own clay bodies, for throwing, ram-pressing &
slip-casting. Some of the clients we make things for occasionally want
to use a clay body they have been using. They buy the appropriate
amount of the clay from whichever manufacturer they use and have it
shipped here. There are some companies and clay bodies we just will
not work with because of variability and failures we have experienced
in manufacturing in the past. I will not out them, but I will say that
Laguna is not one of them.
Jonathan and Jon have known each other for quite awhile, I only met Jon
at NCECA in Indianapolis. But I do know Jonathan, I respect his
knowledge - I know it is based on years of research due to a truly
inquisitive mind and a need to know why, but more importantly on his
years of manufacturing all kinds of ware & trouble shooting. During
those years of trouble shooting, there are particular people he has
called for consultation, and I believe that Jon & Jonathan's
relationship grew out of a mutual respect for each other's knowledge,
and ongoing research regarding the understanding of materials and how
they work, particularly of claybodies.
I know that Jonathan has consulted you on glaze formulation as well.
I think that the discussion has become personal, and there is really no
reason to get worked up about the idea of Standards to the point of
challenging Jon's formulation and testing of the Laguna claybodies.
Laguna is a company that obviously won't give out it's formulas - just
as Standard won't, as Jonathan won't, and I would even suppose that
Tuckers won't give out their proprietary formulas. To insinuate that
Jon Pacini doesn't continuously test the product, or that he doesn't
know how to, is slanderous, and not based on fact. If you are trolling
for groupies, quit it.
There's nothing more to prove - they disagree with an idea you posited,
and just like in a critique, where the discussion is about the work,
not the person, there is no need to get emotionally involved.
best,
Annie
On May 13, 2005, at 12:57 PM, Ron Roy wrote:
> Hi Jonathan,
>
> Long post - I tend to put off answering them - especially those with so
> many different ideas.
>
> I have decided to concentrate on the one aspect that I think is
> important.
>
> When you mix clays for potters - you need to try and provide some
> consistency from batch to batch.
>
> We know the raw materials vary so how do we address that problem?
>
> If we know what absorbency is ideal for what the clay is going to be
> used
> for - we can make adjustments to future batches to keep the clay
> looking
> and acting the same. When we do this we are applying standards.
>
> If we were using variable materials to make glazes we would need to
> apply
> some methodology to limit the variations due to those variations.
>
> What emerges from a program of testing - both manufactures bodies and
> raw
> materials is data from which you can set up your own standards - same
> with
> durable glazes.
>
> During the testing of raw materials it becomes obvious which raw
> materials
> are the most variable - and which are most stable.
>
> It is then possible - when reformulating - to counter the effect of raw
> materials - to use more stable materials when appropriate.
>
> In the end - over years - this can result is much more stable clays -
> that
> need less and less adjusting.
>
> By the way - what is your relationship to Laguna Clays?
>
> I noticed a while ago you said you did not buy clay from clay companies
> anymore - I assumed you had some bad experiences with bought clay
> bodies?
>
> RR
>
>
>> I appreciate the dialog from all sides on this subject. However, I am
>> finding that there are some issues that both semantically and
>> contextually that I am sure not only I but many of the readers on the
>> list are finding perhaps a bit confusing.
>>
>> What I had understood and I am sure many others the same is that the
>> standards apply to clays. I have reviewed many of the posts on this
>> thread and this is indeed the common "thread" in all of them. Now I
>> read that "I was not suggesting that the mines provide standard clays
>> - of course there will always be differences." So now we do indeed
>> have a "baseline" and that baseline is that everything will be
>> different from lot to lot and from bag to bag. So here is a difference
>> of opinion. If everything is different, then how can we develop a
>> standard? Obviously we can't. Remember the talk some years ago about a
>> "Clayart Claybody" ? I had hoped I would not have to bring this bad
>> idea up again now. This was one of the most poorly thought out and
>> poorly conceived ideas that I have ever heard. I am glad it went away
>> by its own attrition and lack of really good thinking and judgement. I
>> remember the phrase/statement/assertion:
>>
>> "We will have our own claybody.....(."left blank intenionally" )will
>> provide the recipie and( "left blank intenionally" )will make it and
>> ("left blank intentionally") will test it." There was a certain degree
>> of pompousness when this came out on the list and I for one had a
>> pretty good chuckle over this one for sure.
>> To me this was a low point on the history of this list. A Clayart
>> Claybody? How funny. What was more than funny was the seriousness on
>> how it was taken as gospel by many on this list.
>>
>> So if we establish a baseline that everything is diffferent, then
>> there
>> can't be a standard. This is a conundrum within a conundrum and a
>> philosophical non-sequitor, The analysis sheets that you still can
>> receive from clay mines and materials producers, from clay companies
>> that blend bodies are relative only to a point in time, a particular
>> shipment, and will vary to some small degree. And they won't tell you
>> what is in the bag. The phrase "representative analysis" is key, and
>> that is exactly what the sheets from the suppliers are. Perhaps that
>> shipment of Newman is higher in iron than the previous one, or the
>> ball
>> clay has a greater percentage of silica or was full of lignite.
>>
>> All is relative and we take it on faith. The weak link in the
>> discussion of standards is the clay itself. You can provide a standard
>> of a particular mixed batch for absorption and shrinkage and you can
>> DTA it to see its expansion and contraction. But other than that, the
>> stuff from the mine is the weak link.
>>
>> I have worked with Newman Red for many years. It reminds me of the old
>> Valentine PBX clay from AP Green years ago. In any of the bodies I
>> have
>> mixed whether it be a casting body or a plastic body it was was either
>> wet screened or dry screened. I also remember when AP Green Dry Milled
>> 28 mesh Fireclay was around. I sieved that also, and Hawthorne. The
>> amount of junk on the screen, the LOI, is amazing. Same with Old Mine
>> 4
>> Ball clay. Mix some of that as a slurry and pass it through a 40 or 50
>> mesh screen. Lots of junk. That's why the stuff in the bag is the weak
>> link and always will be.
>>
>> I would certainly place more value in an analysis of Feldspar or Flint
>> than I would with a clay that's for sure. You can check raw materials
>> for their crystalline structure via x-ray diffraction and see if that
>> sample shows the same peaks and valleys that the previous shipment
>> does. You can dillatometer a clay body and see what the critical
>> points
>> are and see if there is any free silica showing up at the end. And all
>> of these tests, as thorough as they are and whatever value is that the
>> data provides is only relative to what you do with it. You can
>> certainly assert that whatever claybody you make and sell ,according
>> to
>> these afformentioned tests has "x" absorption, "x" shrinkage and has
>> whatever cone range you think it might have. Thats all you can do. You
>> provide the information to the end user only as "insurance" and as
>> comforting the "liability" issues that might be involved. The idea
>> that
>> it will be used in certain perceived "correctness" is I think, at
>> best,
>> a folly.
>>
>> And all you can do is again, provide that as information. You have no
>> standard for how these materials will perform in a potters studio and
>> what conditions they will be used. So standards are only useful, if
>> there were to be any, at the point of blending at Tuckers or Laguna,
>> or
>> where ever. You put these forward in good faith to the best of your
>> ability but you don't and won't know how they will bused and in what
>> conditions. Therein is the problem with "standards" both in context as
>> well as with the semantics of them.
>>
>> Standards/methodology for testing raw materials, yes there are some.
>> Standards/methodology for testing a mixed clay body, yes there are
>> some. But what do you compare the results to? A true representative
>> sample? No such thing. Standards for ascertaining what a certain
>> material "should be," again, no such thing. How many times have you
>> seen lime contamination in coarse Fireclays?
>>
>> Even a company as big as Laguna has little, if any, "clout" with the
>> mines. This is just plain nonsense. We represent such a small
>> percentage of the endusers of these materials that the idea of having
>> clout is more humorous than anything else. Most of the kaolin goes to
>> the paper and to the cosmetic industries, not into ceramics.
>>
>> If you have followed my posts and writings for many years I have urged
>> potters to take responsibility for their clay bodies. There is a
>> rather
>> long discourse on the Digitalfire site entitled "The Whining Stops
>> Here...Taking Responsibility for your Claybody" that I authored years
>> ago. Your book goes a long way to further the idea of responsibility
>> with glazes, But if the glazes sit on an inferior clay body, then it
>> makes not difference if the glaze is balanced or not. The point is if
>> that the claybody is poorly compounded its garbage in and garbage out.
>> Fortunately clay companies like Tuckers, Laguna, etc take the time to
>> test the raw materials. But most of them do not and many of them don't
>> even screen coarse clays. But the limitations of these tests are
>> fairly
>> obvious and anyone with a some knowledge of raw materials will indeed
>> tell you that they are only as good as what the tests are and relative
>> only to a particular time and place, in this case, to a batch that
>> runs
>> through the plant at a particular time. Once its out the door, its
>> open
>> season. That's why the "limits of liability" for the clay body that
>> is
>> in the box that you print on the box in bold type is there. That's
>> because you don't know how it will be used. That's because there are
>> no
>> standards and why these companies protect themselves with "limits of
>> liability".....we will replace the material but not the finished ware.
>> That about summarizes to me, any idea of standards.
>>
>> We take it on faith that our pots don't leak and our glazes won't
>> deteriorate. I am willing to posit that most potters out there
>> wouldn't
>> know how to test for shrink and absorption let alone do a vinegar test
>> on their stuff. Or if they have the ability to blend their own clay
>> send a sample out for a DTA. There is no control, therefore their can
>> be no standard.
>>
>> I would also wonder about how you could make these "perceived
>> standards" more common. I would suggest that you can't. Its a matter
>> of faith. I take it on faith that my stock of Greenstripe, Ti21 Ball
>> Clay, Foundry Hill Creme, FC340, Flint, Spar, Mulcoa, and many other
>> materials is fine. I blend it and test for shrink and absorption, have
>> a DTA run, and when I was making useable ware, tested our glazes for
>> proper fit on the ware. That's all a potter can do. You can't make
>> 'standards" more common because there are no standards. A DTA test is
>> a
>> "standard" test. So is testing for shrinkage and absorption. The acid
>> test with lemon juice is kind of a standard. But what is the acid
>> percentage of the lemon wedge and for how long does it remain on the
>> ware? Provide a standard percentage and a determined time of contact,
>> then you have a standard test.
>>
>> I would also question the " you can get a pretty good idea by looking
>> at the fired clay - especially when there is iron present. It is an
>> excellent way to help diagnose problems." Yes the fired clay can
>> provide visual clues as to what has happened in the kiln. But a
>> "pretty
>> good idea" is not quantifiable. It does not tell me anything. And
>> that's because most potters fire by the seat of their pants and have
>> no
>> idea of what is going on let alone how to even measure it, even as
>> vague as those measurements are. Again, here are differences in
>> semantics and context. Ask a potter how much reduction they get or how
>> good the combustion is to get whatever degree of reduction they want
>> and its met with a blank stare in most cases " uh, I see some back
>> pressure and it smells like ass" Now that's a standard I could
>> certainly get behind and agree with!?
>>
>> If you need standards, then perhaps we need to have firing standards
>> because I don't care if you have the most perfect blended pure clays
>> in
>> your claybodies and the most stable and properly formulated glazes
>> siting on that perfect clay body in the all perfect ceramics world, if
>> you fire it wrong, you negate all the perfect stuff that you put into
>> it to get there. And you get ware that if over-reduced is brittle and
>> defective. The list goes on and on.
>>
>> Standards are only as good as what you perceive them as being even if
>> you could find a way to develop them. That's the problem because you
>> really can't. Clay and glaze technology as applied to the potter's art
>> and craft is like the basis for religion, taken on faith.
>>
>> I'll be the first provide a "huzzah" when I see a list of quantifiable
>> "standards" from the beneficent and omniscient pottery police. Let me
>> know when that happens.
>>
>> I commend the few clay companies for doing proper testing and for the
>> work that you do to help potters with their glazes and helping them to
>> see the importance of proper glaze fit. I think we disagree on some of
>> the basics but we do have some commonality on the necessity for taking
>> responsibility.
>>
>> Respectfully,
>>
>>
>> Jonathan
>>
>>
>> Jonathan Kaplan
>> Ceramic Design Group
>> PO Box 775112
>> Steamboat Springs CO 80477
>> (970) 879-9139
>>
>> Plant location for commercial deliveries excluding USPS
>> 1280 13th Street Suite K
>> Steamboat Springs CO 80487
>>
>> info@ceramicdesigngroup.net
>> www.ceramicdesigngroup.net
>>
>>
>>
>>> Hi Jonathan,
>>>
>>> I was not suggesting that the mines provide standard clays - of
>>> course
>>> there will always be differences - The Feldspar Corporation used to
>>> send an
>>> analysis with each shipment. That could be a standard - and if we had
>>> some
>>> clout with the mines we could insist.
>>>
>>> I was talking about taking responsibility for what we make
>>> particularly
>>> with functional pots - apply some standards - pots that don't leak -
>>> clay
>>> that does not leak when fired to the advertised temperature - glazes
>>> that
>>> don't deteriorate with use.
>>>
>>> We would all be better off if those standards were more common.
>>>
>>> I simply stated that we test every batch of the Newman Red at cone 10
>>> - in
>>> oxidation and reduction - and it works under both conditions - some
>>> one
>>> said a high iron body could not be serviceable in both oxidation and
>>> reduction - I am simply saying - it depends on the formulation - and
>>> it can
>>> be done.
>>>
>>> As for telling if a body is reduced or not and all the variables in
>>> between
>>> - you can get a pretty good idea by looking at the fired clay -
>>> especially
>>> when there is iron present. It is an excellent way to help diagnose
>>> problems.
>>>
>>> Newman is a refractory high iron bearing clay - it has more iron in
>>> it
>>> than
>>> Red Art for instance.
>>>
>>> If you are going to use it you must sieve it - it is one of our more
>>> interesting unrefined clays -.
>>>
>>> RR
>>>
>>>
>>>> I don't know how we can have standards with materials that are
>>>> formed
>>>> in the earth and then processed for industry. They are not
>>>> beneficiated
>>>> by any clay manufacturing company I know of. The extent of
>>>> beneficiation that I have seen is screening coarse fireclays, and it
>>>> still leaves problems. I only know of a few potters that wet mix to
>>>> a
>>>> slurry, Sweco the mix, filter press it and then pug mill it. Then
>>>> and
>>>> only then can there even be some degree of standards. Heck, clay
>>>> body
>>>> mfgs have different penetrometers with different scales so you can't
>>>> use any numbers to base moisture content from supplier to supplier.I
>>>> think to have standards for clay bodies is an effort wrought with
>>>> problems because it is impossible to have a standard from which to
>>>> have
>>>> a baseline. Provide a baseline and I might think differently. But
>>>> what
>>>> baseline and how do you quantify it?
>>>>
>>>> I also question what is full reduction, some or no reduction? The
>>>> only
>>>> way to quantify this is with proper stochiometric combustion
>>>> equipment
>>>> and an oxygen probe. Most potters I know still fire by the seat of
>>>> their pants, at best.
>>>>
>>>> I have used Newman Red in casting bodies and found that after
>>>> sieving
>>>> it to get all the junk out it is a pretty good material to add to a
>>>> clay. I don't know about all the different atmostpheres though, and
>>>> I
>>>> would posit that it does have a very low iron content. I don't have
>>>> my
>>>> data sheet as I am traveling, but I would think that it is pretty
>>>> low
>>>> so it might impart little actual iron thus not acting to provide any
>>>> fluxing action (As Redart does) but just enough color the body. Just
>>>> my
>>>> opinion.
>>>> Jonathan
>>>
>>> Ron Roy
>>> RR#4
>>> 15084 Little Lake Road
>>> Brighton, Ontario
>>> Canada
>>> K0K 1H0
>>> Phone: 613-475-9544
>>> Fax: 613-475-3513
>>>
>>> _____________________________________________________________________
>>> __
>>> _______
>>> 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.
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
> Phone: 613-475-9544
> Fax: 613-475-3513
>
> _______________________________________________________________________
> _______
> 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.
>
Jonathan Kaplan on fri 13 may 05
Hi Ron:
Thanks for taking the time to post your response.
First, let me emphatically state that I have no relationship with=20
Laguna that would at all taint or otherwise cloud what I have to say.=20
Nor do I have any relationship with any other company that produces=20
blended clay bodies. I know most of the principles at many of the=20
companies. I have used blended bodies from Mile Hi, Standard, Laguna,=20
and Aardvark. Mile Hi in Denver is my main supplier of raw materials.
I have been making my own clay bodies and consulting and formulating=20
clays and glazes for others for about 30 years. I do not have a=20
dillatometer. We have 3 clay mixers in our shop...a small stainless=20
Bluebird for 40 pound batches, a beautiful vintage Soldner with=20
stainless steel blades for 300 pound batches, and a 500 pound stainless=20=
steel Rouf's horizontal prepug blender. We have a vintage stainless=20
Bluebird 760, a big Bluebird Powerstar, and a fabulous over/under=20
stainless steel Rouf's(if it ever gets returned to me with the kicker=20
roller installed in the vacuum chamber)
I have 2 sizes of computer electric test kilns.
30 years, lots of books, lots of networking, lots of reading and lots=20
of testing, like yourself. I have taken some chemistry in college. I=20
havehad very good ceramics materials classes at Alfred and RISD in my=20
undergraduate days. Most of what I know is based on those classes and=20
augmented over these many years by reading, experimenting, and working=20=
in the pottery trenches
Yes I now see that you are narrowing your definition of standards.=20
Standards, as I read your posts, applies to how you wish the blended=20
bodies to perform, correct? So in order to do that, we need to have=20
absorption and shrinkage that somehow approaches a known value that=20
your clay company is marketing the clay as, correct? We need to see=20
fired color in both atmospheres at whatever temperature range or=20
specific temperature the clay is marketed for, correct?
So each clay company then has a " standard" for the specific clay body,=20=
and that's all. These might be better off called "requirements."
To arrive at standards for blended clay bodies, you need to test your=20
raw materials. And we know there are many ways to do this and these are=20=
standard ways that any laboratory knows about...x-ray defraction, mass=20=
spectorgraph, shear tests, modulus of rupture, gradient furnace, and a=20=
host of other ASTM type tests. By testing raw materials, we see the=20
variation in them. In fact we might even see that they are a far cry=20
from what they need to be and they get rejected. So if our raw=20
materials meet our requirements, then we can use them in the specific=20
body and then make adjustments for shrink and absorption. Please=20
correct me if I am wrong. We can then even run DTA tests on our=20
individual clays as well as clay bodies to see the heating and cooling=20=
curves, expansion and contraction over time to a specific temperature=20
and in a given atmosphere, correct? You can test for LOI, you can test=20=
for PCE, the list is endless.
What you are doing is a sort of comparative analysis. That's it. If you=20=
find a need to adjust what can be adjusted, you do it. You are taking=20
INDIVIDUAL materials that are variable and with them in a body, trying=20=
to make them compare to whatever set of standards you have in a =20
specific BLENDED BODY.
Correct?
I would posit that this is all you can do. As I posted earlier, you=20
have faith and trust that with all the testing and blending and=20
adjusting, you get something that might work. But again, to reiterate,=20=
there is little control of the individual raw materials. Hell, the guy=20=
running the front end loader at the fireclay or stoneware clay mine=20
perhaps didn't get laid the previous nite and then went on a bender. He=20=
scrapes a small layer of coal or limestone in with that clay. You know=20=
the results if coarse clays are not screened.
So maybe, as I posted earlier, that this is purely a question of=20
semantics and language. Perhaps we all misunderstood each other in=20
definition and etymology?
So here's what I am distilling and agree with from all this verbiage=20
from the many weeks on this thread:
1. You can test RAM materials to see if they are what they are and if=20
they conform to the mineralogy that they should.
2. You blend a clay body and test for absorption, deformation,=20
shrinkage, DTA, etc etc and see if it conforms to whatever standards=20
you have set
within your company for that specific body. Then if you have to=20
make some change to get the body to conform to your standards, you can=20=
do
precisely that.
3. With all this, you still have no control that it will be used=20
correctly in a studio or school setting.
Am I right so far?
With all the changes in the world of minerals and corporations buying=20
and selling each other, what are things that one can do to provide a=20
reasonable change that blended clay bodies will work with a minimum of=20=
difficulty?
Here's what I would do, and I also understand that many can't blend=20
their own clay bodies or even have the desire to do so.
1. I take it on faith that my flint, feldspars, pyrophyllite, are=20
close to their known standard. In all my years of working with these=20
materials, they
never proved to be problematic, at all.
2. Avoid coarse fireclays and if you must use Hawthorne 35 or 50,=20
Newman, bonding clays, etc. etc., dry screen them first
3. I have never had any problems with Greenstripe fireclay and have=20
been a faithful user for many years.
4. I also take it on faith that the kaolins I use, Pioneer AF, Tile 6,=20=
Velvacast, are close to their known standard.
5. I never use any ground firebrick culls as grog. I always use a known=20=
refractory calcine, in this case Mulcoa.
6. I always use airfloated materials when I can.
7. I minimize the amount of red clays. If I want a "colored" body I=20
will use a small amount of Red Art or iron oxide, or Newman.
8. I work with a set of well tested ratios between plastics and non=20
plastics. I developed these ratios in the late 1970's and they have=20
proved to be
correct over these many years in casting bodies and plastic bodies=20=
I have developed for jigger, Ram=A9 press, throwing etc.
9. I use correct ball clays for specific clay bodies. I don't use OM4=20=
any more as it is garbage. I use ball clays developed for casting for=20
casting
bodies. such as FC 340. I use light fired ball clays such as Ti21=20=
for my mid range white bodies.
10. I use a great deal of New FHC in most of my clay bodies at al=20
temperature ranges.
And finally.........
I stay away from anything in the low temperature range of cone 06-04=20
such as low temperature white bodies and terra cotta bodies. Generally=20=
these bodies are garbage. I don't like using frits in this range as=20
body fluxes. I have duplicated these bodies at cone 4-5-6 and they are=20=
all winners because the selection of materials is better. You can use=20=
many of the low temperature underglaze systems at these temperatures,=20
even higher. I stay away from the low temperature glazes as IMHO, they=20=
are not very good glasses.
I have never looked at raw clays or blended bodies as being stable. To=20=
me, that's kind of a joke. I'm just happy my formulas work.
Yes, I don't buy blended clay bodies for my own work. I am not very=20
trustful of the formulae and I am even more apprehensive of human error=20=
in making clay. I don't wanna bitch and moan to these guys if the=20
bodies suck. If I make a mistake I can blame myself and correct it. I=20=
have never purchased clay in the box that has the moisture correct. Its=20=
either like baby poop or its way hard. Only one company that I know of=20=
can get the moisture content correct for clay bodies for the RAM=A9=20
press. You may be able to throw a great number of the commercial=20
blended clay bodies but you cannot press all of them because they are=20
not formulated correctly for pressing. I have worked extensively with=20
these issues for many years and know how to select the correct=20
materials in the correct ratios for these processes. I am lucky to have=20=
this knowledge and the ability to blend what I want and get it right.=20
If I had a filter press, I would wet blend all my plastic bodies. We=20
blend and screen 350 gallons of casting slip each batch (3500 pounds=20
dry) and it works correctly every time. I have found everything from=20
cigarette butts, nuts and bolts and assorted hardware etc etc. in=20
blended commercial clay bodies. That kind of stuff would never show up=20=
in clay we make here. I also received a 4000 pound batch of dry blended=20=
Terra Cotta that was contaminated with silica sand because someone=20
didn't read the bag correctly or couldn't read at all or didn't follow=20=
the corrct cleaning procedure for the machinery at the company. Most=20
recently, a colleague in Pennsylvania received part of a 6000 pound=20
batch from an east coast clay company that had the wrong sized Mulcoa=20
in it. Instead of a smooth throwing body he received a loat or coarse=20
groogy clay. The company admitted that they put the wrong sized Mulcoa=20=
in it. And these are just a few of the many stories from "clay in the=20
box" land. And that's why I won't go that route. Fortunately, I can mix=20=
what I want to at our facility.
I certainly don't know everything, in fact, I know perhaps a small=20
amount of information. But I do know what works and further, what works=20=
for us in our working situation.
I am pleased that you have a program of testing. I know Laguna has a=20
very intensive testing program.
So what else do you wanna know?
Respectfully,
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
(please use this address for all USPS deliveries)
Plant Location:
1280 13th Street Suite K
Steamboat Springs CO 80487
(please use this address for all UPS, courier, and common carrier=20
deliveries only!!)
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
On May 13, 2005, at 12:57 PM, Ron Roy wrote:
> Hi Jonathan,
>
> Long post - I tend to put off answering them - especially those with =
so
> many different ideas.
>
> I have decided to concentrate on the one aspect that I think is=20
> important.
>
> When you mix clays for potters - you need to try and provide some
> consistency from batch to batch.
>
> We know the raw materials vary so how do we address that problem?
>
> If we know what absorbency is ideal for what the clay is going to be=20=
> used
> for - we can make adjustments to future batches to keep the clay=20
> looking
> and acting the same. When we do this we are applying standards.
>
> If we were using variable materials to make glazes we would need to=20
> apply
> some methodology to limit the variations due to those variations.
>
> What emerges from a program of testing - both manufactures bodies and=20=
> raw
> materials is data from which you can set up your own standards - same=20=
> with
> durable glazes.
>
> During the testing of raw materials it becomes obvious which raw=20
> materials
> are the most variable - and which are most stable.
>
> It is then possible - when reformulating - to counter the effect of =
raw
> materials - to use more stable materials when appropriate.
>
> In the end - over years - this can result is much more stable clays -=20=
> that
> need less and less adjusting.
>
> By the way - what is your relationship to Laguna Clays?
>
> I noticed a while ago you said you did not buy clay from clay =
companies
> anymore - I assumed you had some bad experiences with bought clay=20
> bodies?
>
> RR
>
>
John Hesselberth on fri 13 may 05
On Friday, May 13, 2005, at 03:55 PM, Annie Chrietzberg wrote:
> The idea that the materials that we use are stable just isn't
> realistic.
Annie, Jon, Jonathan,
I get the feeling you are having so much fun ganging up on Ron that you
aren't even trying to understand what we is saying. He never said or
implied the above, although he did say some materials are more
reliable/stable than others and one might want to favor using those
were possible.
What he did say is that clay bodies can be made to a standard, i.e.
they have the same shrinkage and absorption at a given cone, be free of
garbage, etc. It requires analyzing the materials as they come in,
adjusting the recipes on an ongoing basis, and taking care in the
screening and mixing of the body to produce a consistent clay body that
a potter can trust to be the same over time. The quality clay body
suppliers are doing this today. We know it can be done and those who
say it can't are just making excuses for a shoddy operation. There are
also a number of suppliers making highly variable bodies that potters
find very frustrating. Ideally the market will drive those poor quality
suppliers out of business but, unfortunately, it doesn't seem to happen.
Now please, if you are going to continue this discussion try to
understand what each other is saying before flying off the handle.
Regards,
John
Ron Roy on sat 14 may 05
Hi Annie,
I never said that - Jonathan and Jon think that is what I said - I have
corrected them a couple of times already.
What I am saying is - there should be some standards in place for clay
bodies - so potters have some idea about what any particular clay is good
for.
Does it leak when fired to this temperature - in other words does it have
an absorbency between 3% and none.
When you make and sell a glaze - why not include the information about
durability?
When you buy cones - will they give the right temperatures - are fire
bricks all the same size.
Standards - helpful - thats all.
RR
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
URL Krueger on sat 14 may 05
I know by jumping in here I'm at risk here of being either
bit or ignored by the big dogs, but...
When I go to the grocery store and buy a gallon of 2% milk I
have certain expectations of what it will be like when I
get it home; not soured, no "off" flavors, not too rich or
too watery, etc.
When I go to the pottery supply store and buy a bag of clay
I have certain expectation of what it will be like when I
get it home; not too wet or dry, no splinters of broken
glass, not too coarse or too fine, matures at the
temperature specified, not "off" color, etc.
I almost never get a gallon of milk that doesn't meet my
expectations but it seems like every bag of a clay body I
get from a different batch is, well, noticeably different
in one way or another. Since both clay and milk are
natural products that have been modified by industrial
processes, why this difference? (Admittedly, there is
legislation that specifies the requirements for milk but
none, that I know of, for clay.)
Isn't this what this whole thread, prima facia, has been
about? If clay suppliers were to develop standards for
their clay bodies and produce to these standards wouldn't
the product we consumers purchase be more uniform and
predictable? Wouldn't our expectations more likely be met
when we got the bag of clay home? Wouldn't we be happier?
Of course, the standards (or requirements) could be too
lenient in which case we must let the supplier know that
their product is not meeting our expactions and they must
tighten them up if they want our continued business.
And, as in all things, if we want quality we must be willing
to pay for it.
Earl K...
Bothell WA, USA
Earl Brunner on sat 14 may 05
I wouldn't consider myself a "big dog" in this issue, but I'm just not sure the analogy holds up. Cows milk is pretty much cows milk, as long as you don't feed them onions or garlic, it's probably going to taste pretty much the same. Sure, the butterfat varies and they adjust that, and some kinds of cows produce more than others and higher or lower butterfat milk. (the fact that I have convinced some first graders that the brown (chocolate) milk come from brown cows, white milk from white cows and pink (strawberry) milk from pigs is irrelevant). The clays that we use on the other hand aren't that easy to categorize. The variables are huge and we don't have mammary glands to run it through.
Do I think it would be good to have the producers do a better job of trying to be more consistent and could they provide the end user with more information about absorbency, shrinkage, etc. sure. But if past performance is any indicator, don't hold your breath.
URL Krueger wrote:
I know by jumping in here I'm at risk here of being either
bit or ignored by the big dogs, but...
When I go to the grocery store and buy a gallon of 2% milk I
have certain expectations of what it will be like when I
get it home; not soured, no "off" flavors, not too rich or
too watery, etc.
When I go to the pottery supply store and buy a bag of clay
I have certain expectation of what it will be like when I
get it home; not too wet or dry, no splinters of broken
glass, not too coarse or too fine, matures at the
temperature specified, not "off" color, etc.
I almost never get a gallon of milk that doesn't meet my
expectations but it seems like every bag of a clay body I
get from a different batch is, well, noticeably different
in one way or another. Since both clay and milk are
natural products that have been modified by industrial
processes, why this difference? (Admittedly, there is
legislation that specifies the requirements for milk but
none, that I know of, for clay.)
Earl Brunner
e-mail: brunv53@yahoo.com
Jonathan Kaplan on sat 14 may 05
Hi Earl:
Your post is right on and I would certainly not ignore what you have
written as it is quite correct. (btw..I don't see myself as a big dog
at all)
Different manufacturers of prepared clay bodies all have their unique
proprietary formulas and do custom blending of private formulas. All
these formulas are different not only in what the constituent
ingredients are but in how they are fired and what is to be expected.
And all manufacturers have their own set of "requirements,
expectations, standards" etc and this is exactly what this long winded
thread and discussion has been about.
The end products, the blended clay bodies, pugged, de-aired, bagged and
boxed should meet the "requirements, expectations, standards" that
each company has set up. That is all I think this discussion has been
about. Where it has got side tracked is "how to get there" without
overlooking the point that all the raw materials will vary from batch
to batch. I think there was some misleading or semantic errors
initially, but I would think that pretty much we all agree on the basic
stuff.
You have certainly illustrated quite nicely the entire few weeks of
discussion into once nicely distilled posting. Thanks for putting this
into a proper perspective and for taking the time to think about it!
Best
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
(please use this address for all USPS deliveries)
Plant Location:
1280 13th Street Suite K
Steamboat Springs CO 80487
(please use this address for all UPS, courier, and common carrier
deliveries only!!)
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
On May 14, 2005, at 2:41 PM, URL Krueger wrote:
> I know by jumping in here I'm at risk here of being either
> bit or ignored by the big dogs, but...
>
> When I go to the grocery store and buy a gallon of 2% milk I
> have certain expectations of what it will be like when I
> get it home; not soured, no "off" flavors, not too rich or
> too watery, etc.
>
> When I go to the pottery supply store and buy a bag of clay
> I have certain expectation of what it will be like when I
> get it home; not too wet or dry, no splinters of broken
> glass, not too coarse or too fine, matures at the
> temperature specified, not "off" color, etc.
>
> I almost never get a gallon of milk that doesn't meet my
> expectations but it seems like every bag of a clay body I
> get from a different batch is, well, noticeably different
> in one way or another. Since both clay and milk are
> natural products that have been modified by industrial
> processes, why this difference? (Admittedly, there is
> legislation that specifies the requirements for milk but
> none, that I know of, for clay.)
>
> Isn't this what this whole thread, prima facia, has been
> about? If clay suppliers were to develop standards for
> their clay bodies and produce to these standards wouldn't
> the product we consumers purchase be more uniform and
> predictable? Wouldn't our expectations more likely be met
> when we got the bag of clay home? Wouldn't we be happier?
>
> Of course, the standards (or requirements) could be too
> lenient in which case we must let the supplier know that
> their product is not meeting our expactions and they must
> tighten them up if they want our continued business.
>
> And, as in all things, if we want quality we must be willing
> to pay for it.
>
> Earl K...
> Bothell WA, 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.
>
>
John Britt on sat 14 may 05
Earl k, Earl B, Jon, Ron, Jonathan, et al,
I think a better analogy would be cooking. For example: many people make
lasagna differently although the finished produce could be thought of a
belonging to the category "Lasagna". Some will love your lasagna, yet
others will complain that =93this is not real lasagna=94. They may even
claim, =93I make the only real lasagna! In fact, your lasagna sucks!=94
I believe that clay companies have smart and hardworking employees who try
their hardest to make the best product possible, because they want to sell
more clay with fewer complaints. But variation in materials is a fact. As
is firing variations, drying variation, etc. (ad nauseam)
People do many crazy things with clay bodies, many things that are not
intended when the body was designed. As they say: =93mileage may vary=94. Bu=
t
that does not make the clay body bad or the makers stupid. Nor do I
believe that one person/company makes a superior clay body to all others!
People have preferences, many many preferences. For example: they want
dark clay bodies because they fire in oxidation and want some color,
others fire in reduction and so they want lighter clay bodies with a
toasty color. Others just sample clay bodies in their cycle and see what
they get. Some start heavy reduction at cone 014 to get carbon trapping,
others start at the beginning of the firing and fire with heavy reduction
to peak temperature and then reduction cool. I know this is crazy but you
never know what people are capable of trying. This is the creative mind at
work. You cannot control the creative mind.
But that doesn=92t make the clay body bad or poorly formulated. It may make
us long for standards, to have some semblance of control in our lives, but
that certainly does not mean we will get those standards nor achieve them.
The purist will want a =93lasagna=94 standard with amounts of oregano, basil=
and tomato, all spelled out. But trying to get everyone to agree the
definition of the terms let alone on what that standard is, is next to
impossible.
Thanks for the discussion,
John Britt
www.johnbrittpottery.com
Lee Love on sun 15 may 05
URL Krueger wrote:
>When I go to the grocery store and buy a gallon of 2% milk I
>have certain expectations of what it will be like when I
>get it home; not soured, no "off" flavors, not too rich or
>too watery, etc.
>
Hi Earl,
Most of the qualities in milk that you are describing are physical
qualities. The main way these qualities are achieved is by mixing milk
from various sources in very large quantities. It has little to do the
the industrialization of materials that folks were proposing earlier.
And we drink huge amounts of milk, compared to how much clay potters use
back home. The high production volume of milk allows for higher levels
of consistency. Quality is also helped by the large, discriminating
consumer base.
If you work with ash glazes as I do, it becomes apparent quickly, that
larger batches of ash need to be processed , and then they need to be
tested before you use them on your pots, if you want consistency from
this natural material.
Our clay here in Mashiko is minimally processed, but I have never had a
bad batch of clay here. Why? Because it is mixed up in large batches.. I
am guessing Mashiko produces and consumes much more clay than it does
milk. The amount of clay used in Tochigi prefecture alone, I would
guess, is more than all the clay used by potters in all of North
America. It is difficult to comprehend unless you see it for yourself.
Natural, unrefined materials help us create pots that have life. As
Okakura, the author of The Book of Tea says: "Nowadays industrialism is
making true refinement more and more difficult all the world over." The
beauty of the imperfect isn't the only aesthetic, but it is a valid
alternative one. It remedies what is wrong with the throw-a-way society.
I defend it because it is in constant threat from cheaply produced
industrially made products. Because folks are protected from the world
of touch, they are loosing the ability to discriminate tactically. We
need handmade things, and we need more people creating things with their
hands, than we have ever needed them in the past. I believe it is an
important way we can keep from being turned into mere consumers.
Below, I include a larger quote from Okakura. I hope it helps to explain
the aesthetic of imperfect beauty:
"The Taoist and Zen conception of perfection, however, was different.
The dynamic nature of their philosophy laid more stress upon the process
through which perfection was sought than upon perfection itself. True
beauty could be discovered only by one who mentally completed the
incomplete. The virility of life and art lay in its possibilities for
growth. In the tea-room it is left for each guest in imagination to
complete the total effect in relation to himself. Since Zen has become
the prevailing mode of thought, the art of the extreme Orient has
purposefully avoided the symmetrical as expressing not only completion,
but repetition. Uniformity of design was considered fatal to the
freshness of imagination. Thus, landscapes, birds, and flowers became
the favorite subjects for depiction rather than the human figure, the
latter being present in the person of the beholder himself. We are often
too much in evidence as it is, and in spite of our vanity even
self-regard is apt to become monotonous.
The simplicity of the tea-room and its freedom from vulgarity make it
truly a sanctuary from the vexations of the outer world. There and there
alone one can consecrate himself to undisturbed adoration of the
beautiful. In the sixteenth century the tea-room afforded a welcome
respite from labour to the fierce warriors and statesmen engaged in the
unification and reconstruction of Japan. In the seventeenth century,
after the strict formalism of the Tokugawa rule had been developed, it
offered the only opportunity possible for the free communion of artistic
spirits. Before a great work of art there was no distinction between
daimyo, samurai, and commoner. Nowadays industrialism is making true
refinement more and more difficult all the world over. Do we not need
the tea-room more than ever?"
You can find the whole Book Of Tea here:
http://ikiru.blogspot.com/2005_04_03_ikiru_archive.html#111257654464573093
--
ζ Lee Love 倧
ζγγ γγ ι±
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
Lee Love on sun 15 may 05
Edouard Bastarache Inc. wrote:
> Is he a worse artist-potter?
> Are his pots crap?
Yeah. Crap potters, like Hamada and just about every other country
potter in Japan. ;-)
Really, we need to think about what kind of aesthetic comes out of
absolute control? Sure, total control is good for some folks and is
appropriate for some aesthetics, but not for all ways of working. Viva
la Difference!
I bisqued test tiles of the new clay from the quarry near where I live.
Jim in Saitama gave me a small electric jeweler's type kiln that has a
ware space of about 3/4ths of a brick. I was able to bisque 14 tiles in
it in less than an hour. I did straight versions of both clays, 50/50
blends of both and also a blend of the ocher colored clay with han jiki
(porcelain and stoneware mix.) Also added 10% and 5% additions of
refractory ball clay (keibushi) to the Mashiko standard clay. Will be
interesting to see what comes out.
--
ζ Lee Love 倧
ζγγ γγ ι±
in Mashiko, Japan http://mashiko.org
http://hankos.blogspot.com/ Visual Bookmarks
http://ikiru.blogspot.com/ Zen and Craft
Ron Roy on sun 15 may 05
Hi Jonathan,
First of all I have no clay company - I am a consultant to who ever needs
my services. I in no way share in the profit of any supplier of any
product. I think of myself as working for potters and - in the case of
suppliers of clay - they make it possible.
I remember a thread here on ClayArt not long ago - about if it makes sense
for potters to do workshops - for the money or for the fame - I found it
strange that no one brought up the other reason - because it needed to be
done.
When you set standards for clay bodies you wind up setting different
standards for different types of clays - Stonewares, porcelains and earthen
ware. Each type requires different standards. There are types within the
three main groups that have special requirements as well - the high iron
stonewares are one such group.
Take for instance a raku body - one that can also be used for functional
ware at cone 6. Normally absorbency is not a factor for a raku clay - but
if the body is regularly tested at cone 6 it can be keep within standards
for cone 6 as well.
The is no high tech equipment in the labs I work with - getting the right
data is simple enough - what is done with that data is the important part.
I takes a determined effort to maintain accuracy in the testing methods and
constant reaction to the results to make sure a clay body does what it is
advertised to do. It's not difficult but it does take a "attitude."
The exception to the above about equipment is the dilatometer. They are
expensive and demanding in they care and use. Before I had the use of one I
did not realize just how important the different forms of SiO2 had on clay
bodies. It certainly has changed my way of working with high fired
stoneware clays.
I am not saying my methods are the ultimate or they can't be improved - I
am saying my attitude is the important part. I am willing to do what is
necessary to convince potters that testing and adjusting clay bodies is
necessary to get good results - because the materials we use are variable.
One of the great advantages of testing raw materials by the way - you know,
over time, which materials vary the most - those materials that do vary a
lot can be gradually diminished or replaced in a body when less variable
materials are available - when it is appropriate.
RR
>Yes I now see that you are narrowing your definition of standards.
>Standards, as I read your posts, applies to how you wish the blended
>bodies to perform, correct? So in order to do that, we need to have
>absorption and shrinkage that somehow approaches a known value that
>your clay company is marketing the clay as, correct? We need to see
>fired color in both atmospheres at whatever temperature range or
>specific temperature the clay is marketed for, correct?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ceramic Design Group on sun 15 may 05
I think we have reached an acceptable equilibrium with all this. I know
I have.
Thanks for addressing my posts.
You mentioned the high iron stonewares.....
> There are types within the
> three main groups that have special requirements as well - the high
> iron
> stonewares are one such group.
I learned that since all clays are not for all of us and considering
that there seemed to be a waning of the reduction look..."spotted
stoneware" or how ever it would be described, that for our purposes in
our facility, it would behoove me to eliminate those types of clays and
the potential detriment that they could impart to wares. I remember
many years ago when I changed to a white stoneware/porcelaineous
stoneware how much better the glazes looked. This occurred in the early
1980's. The ware became much better because the glazes had more life.
We could work with many different decorating techniques and have them
actually show up! I have since only used red clays as colorants for a
white body if a client requests it. Over these years, we have relied on
Imery's and Dry Branch products for our kaolins and have never been
disappointed. Old Hickory provides our ball clays, and the usual
sources for feldspars, flint, refractory calcines, etc. We have over
time still used Greenstripe and are quite satisfied even thought it is
a high silica material. Thats why all our bodies have Pyrophyllite in
them, and even the one that don't have Greenstripe have pyrophyllite.
If I had to choose, I would certainly not chose to be in the clay
making business as it is quite a responsibility. I also understand that
most potters don't mix their own clay bodies or even care to, and that
is a very good choice also. Who wants all the expense of equipment,
material handling equipment and what ever else is needed.
Buying clay in the box is convenient and efficient. It brings with it
a commitment, dependency, and ultimately a responsibility on people
like you and Jon Pacini to insure that what goes into the box is a
quality material. We may differ in our opinions about what "standards
or requirements or base lines" or what ever we wish to call them and in
what context we wish to apply them, but none the less I do think what
you all do is important. That's the most essential thing to come out of
this entire dialog. I don't think it makes any of us better or worse
for that matter. it s all about information and what you do with it.
And it is about making a quality clay body.
I'm pretty lucky even though I do have a small fortune tied up in
mixing equipment. One bozo employee left a hose in contact with the
Sweeco screen and over time it damn wore right through it and cost a
pretty penny for a new super taunt screen and to have it sent in
overnight. Just as you make sure that the clay is ok, I do the same on
a much smaller scale to make sure that the clays I formulate will
provide quality product for my clients. We currently run a midrange
cone 5-6 whiteware casting body and a cone 9-10 white stoneware plastic
body suitable for jiggering and pressing. It also throws like magic.
The same concept of "standards" applies. So all of us do the same
thing, yet in different ways, that's all.
Best
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
(970) 879-9139
Plant location for commercial deliveries excluding USPS
1280 13th Street Suite K
Steamboat Springs CO 80487
info@ceramicdesigngroup.net
www.ceramicdesigngroup.net
On May 15, 2005, at 3:23 PM, Ron Roy wrote:
> Hi Jonathan,
>
> First of all I have no clay company - I am a consultant to who ever
> needs
> my services. I in no way share in the profit of any supplier of any
> product. I think of myself as working for potters and - in the case of
> suppliers of clay - they make it possible.
>
> I remember a thread here on ClayArt not long ago - about if it makes
> sense
> for potters to do workshops - for the money or for the fame - I found
> it
> strange that no one brought up the other reason - because it needed to
> be
> done.
>
> When you set standards for clay bodies you wind up setting different
> standards for different types of clays - Stonewares, porcelains and
> earthen
> ware. Each type requires different standards.
> Take for instance a raku body - one that can also be used for
> functional
> ware at cone 6. Normally absorbency is not a factor for a raku clay -
> but
> if the body is regularly tested at cone 6 it can be keep within
> standards
> for cone 6 as well.
>
> The is no high tech equipment in the labs I work with - getting the
> right
> data is simple enough - what is done with that data is the important
> part.
> I takes a determined effort to maintain accuracy in the testing
> methods and
> constant reaction to the results to make sure a clay body does what it
> is
> advertised to do. It's not difficult but it does take a "attitude."
>
> The exception to the above about equipment is the dilatometer. They are
> expensive and demanding in they care and use. Before I had the use of
> one I
> did not realize just how important the different forms of SiO2 had on
> clay
> bodies. It certainly has changed my way of working with high fired
> stoneware clays.
>
> I am not saying my methods are the ultimate or they can't be improved
> - I
> am saying my attitude is the important part. I am willing to do what is
> necessary to convince potters that testing and adjusting clay bodies is
> necessary to get good results - because the materials we use are
> variable.
>
> One of the great advantages of testing raw materials by the way - you
> know,
> over time, which materials vary the most - those materials that do
> vary a
> lot can be gradually diminished or replaced in a body when less
> variable
> materials are available - when it is appropriate.
>
> RR
>
>
>> Yes I now see that you are narrowing your definition of standards.
>> Standards, as I read your posts, applies to how you wish the blended
>> bodies to perform, correct? So in order to do that, we need to have
>> absorption and shrinkage that somehow approaches a known value that
>> your clay company is marketing the clay as, correct? We need to see
>> fired color in both atmospheres at whatever temperature range or
>> specific temperature the clay is marketed for, correct?
>
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
> Phone: 613-475-9544
> Fax: 613-475-3513
>
> _______________________________________________________________________
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>
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>
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> melpots@pclink.com.
>
>
Jon Pacini on mon 16 may 05
Greetings All-- Over the weekend quite a few others jumped into this thread
and that was certainly a good thing. John Britt brought in some good points,
as did Lee Love and the Earls. Edouard, you sure know how to turn a phrase,
as always. To John H-- thanks for helping to qualify things a bit. I don't
think all of us were ganging up on Ron, his post just wasn't specific and
was open for a lot of differing interpretation.
So----, Ron's position on standards got qualified and narrowed down a bit.
I, like Jonathan, read Ron's post as a broad call for clays to meet some
collective universal standards, a situation all seem in the end to have
agreed on as a bit unrealistic. The clarified position that clay
manufacturers should publish the characteristics of the clays they produce
and then live up to them, is certainly more realistic. This is something
that Laguna and it's predecessor company Westwood have done since the early
1970's. I haven't checked, but I'll take a leap and say so do the companies
Ron consults for. I'm not familiar with every manufacturer, but I imagine
some do and some don't. Publish or live up.
For the Local clay maker whose budget just doesn't include the funds for
catalog publishing, the type of equipment necessary for extensive testing or
for a consultant to prepare this info for them, this becomes more
problematic.
In lieu of published numbers being available, potters should talk to the
clay maker and find out exactly what they are doing in the way of quality
assurance and what you should expect from the clay you are buying. If you
are not comfortable using clay from them, find someone you are comfortable
with. Don't make assumptions that they are doing testing that they are not.
Making that assumption is nobodies fault but you own and an ingredient for
disaster.
Any customer that calls Laguna is welcome to the data we possess on that
clay. Every box of clay and bag of glaze has a batch number on it that is
used to track it thru the manufacturing and QA process. All that info is on
file going back many years.
I'm not going to go into detail of the entire process we use for Qa here.
I've covered it in past Posts to the list. If you have any specific
questions, drop me a line. I'll take them on one at a time.
I'm not that much into blowing my own horn and I hate to come off as some
talking suit from some corporation. Others who post regularly to the list
have toured the Laguna facility and have their impressions of the work we do
here in regards to R&D, manufacturing and QA. I do appreciate Jonathans
post regarding his impressions, Mel was here in the plant on Friday and I
hope he will share with you his impressions of our set up. I can't think of
anyone more qualified than those two to assess a clay making/QA operation.
Ron asked what happened to the COE's on the clays I was collecting. I've got
the data on nearly all the Laguna bodies done. The equipment got taken over
for other, more pressing projects. The fact that I've had exactly 3 calls
for any COE numbers in the last 6 months hasn't exactly lit a fire under
this project. Management likes to give me flack about this project, their
reasoning is that nobody really cares about the COE's and I'm wasting time.
The calls or lack there of, seems to bare this stance out.
If you have a question on the COE of the Laguna clay you are using, for the
time being, give me a call or drop me a line. If you want the physical COE
of the clay as it applies to your particular firing schedule, because that
can make a difference, we can do that too. Drop me a line and I'll let you
know what that entails.
Adios y via con dios amigos
Jon Pacini
Clay Manager
Laguna Clay Co
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