Megamelon on sun 18 mar 07
Do commercial companies generally protect clay body formulas? Do they =
generally at least give a unity-type analysis if asked?
I'm currently using Amherst Z
Just got Glazemaster and am having fun so far...
Lois Ruben Aronow on mon 19 mar 07
Short answer: yes, they do protect their formulas, although they will give
you the shrinkage and absorption rate, tell you if it contains ball clay...
Real life answer: What matters just as much - sometimes more - is what YOU
do. How YOU bisque. How YOU throw (or build). How YOU fire. How YOU mix
your glaze. YOUR water. The mine YOUR chemicals came from, and how old
they are. YOUR firing schedule. YOUR kiln. Yes, YOUR kiln.
A studio mate fired his first glaze in my kiln after years and years of
firing his own kiln before he moved. Same kiln type and model - Skutt
1027KM. He used the same ramp schedule he has been using for eons. Same
bisque schedule. He used cones. Same glaze he made at his home upstate
before moving to Brooklyn. Same claybody he brought with him, and has been
using for ages.
The moral of the story is: his work came out different in my kiln. Not bad
different, just DIFFERENT. His brown was so much richer; his white, kinda
not as rich as in his other kiln.
TEST TEST TEST. I can't say this enough. I know so many people despise
this answer, but there are no shortcuts. No excuses. No way to make your
work exactly the same way every time. And that's the beauty of it.
...Lo
***
Lois Aronow Ceramics
www.loisaronow.com
www.craftsofthedamned.blogspot.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Megamelon
Sent: Sunday, March 18, 2007 10:05 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Commercial clay body formula
Do commercial companies generally protect clay body formulas? Do they
generally at least give a unity-type analysis if asked?
I'm currently using Amherst Z
Just got Glazemaster and am having fun so far...
____________________________________________________________________________
__
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.
Thomas Malone on mon 19 mar 07
Hello,
Yes commercial companies generally do protect the formulae for their
bodies. But it would it would be wrong to even think about using unity
formulae for bodies, and the same for glaze calculation programs. These are
based on Zachrisson's theories and so are for glasses alone. What
commercial companies should supply, if asked nicely, are typical chemical
analysis for their bodies
Ron Roy on tue 20 mar 07
Hi Thomas,
I don't know where you found the info that calculation cannot be used for
clay bodies - I use the unity formula for subbing in different clays all
the time.
It is also a wonderful help when adjusting the firing temperature of clay
bodies that drift because of raw material fluctuations.
I'm curious - what makes you think you could not compare say two cone 6
bodies - or even lower a cone 8 body to cone 6 after looking at the
molecular formula for other cone 6 bodies?
RR
>Hello,
>
>Yes commercial companies generally do protect the formulae for their
>bodies. But it would it would be wrong to even think about using unity
>formulae for bodies, and the same for glaze calculation programs. These are
>based on Zachrisson's theories and so are for glasses alone. What
>commercial companies should supply, if asked nicely, are typical chemical
>analysis for their bodies
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Megamelon on tue 20 mar 07
Lois: "TEST TEST TEST. I can't say this enough. I know so many people =
despise=20
this answer, but there are no shortcuts. No excuses. No way to make your =
work exactly the same way every time. "
Hey- I have no problem with testing. I love testing.
Theory guides and experiment decides. I'm just=20
having fun with the theory part here.
Oh, and I'm really interested because I was hoping to sieve the=20
clay and use it in a glaze- not just trying to fit the body. It'd=20
be nice to have a vague starting point on composition, make up=20
a series, and see if my guess on best composition was right.
May Luk on wed 21 mar 07
Hello Lois and whoever reading this;
This is interesting of your observation about your
studio mate's wares. I had the same feeling recently
cooking with my new Le Cruset cast iron pot with my
usual braise chicken recipe with leeks. I could not
duplicate the dish with my good old All Clad paella
pan (shipped in from NYC) cooked in LondON. Weird!
Onto clay analysis; I cannot find the analysis for my
B-Mix (cone 5) on the web and I asked Joe at Laguna
and he said there is none. I am fine with their
company policy but I am also cross. I only want to
make some slip / engobe with the clay scrap and do
some maths about it. With respect to the clay
company, but I don't know what is the fuss about
non-disclosure. It is all theoretical anyways.
Regards
May
Kings County, USA
Ron Roy on thu 22 mar 07
Hi May,
Don't know if it will be of much help but - in Canada it is the law - that
the % analysis of any product must be included in the MSDSheets - if there
is any toxic material present - like silica.
All you need to do is find a supplier in Canada that sells the clay and
they have to suppy an analysis.
It is possible to get to a unity formula from the analysis if you know how
to juggle a bit.
RR
>Onto clay analysis; I cannot find the analysis for my
>B-Mix (cone 5) on the web and I asked Joe at Laguna
>and he said there is none. I am fine with their
>company policy but I am also cross. I only want to
>make some slip / engobe with the clay scrap and do
>some maths about it. With respect to the clay
>company, but I don't know what is the fuss about
>non-disclosure. It is all theoretical anyways.
>
>Regards
>May
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Thomas Malone on fri 23 mar 07
Hello Roy. It is not that calculations can not be used for clay bodies, far
from it. It is just that it is invalid to apply glass theory to bodies.
These assume the complete melting of all components to form a glass, where
as bodies are composed of glass and crystalline phases that never melted.
You are fortunate to have achieved success by using unity formulae for
bodies, but why use this method when other more appropriate methods are
available?
Thomas
Ron Roy on sun 25 mar 07
Hi Thomas,
Perhaps we are not talking about the same thing - are you saying calculated
expansion is no good for bodies? - if so I would agree.
I have to assume you have not used the method to "fix" clay bodies - I also
use % analysis as a quick check after I have used unity - but always start
with unity and only a few time find it necessary to alter after I look at
the analysis.
I monitor the clays for a local clay company and adjust them on a regular
basis to correct for shrinkage and absorbency - I have found the results to
be very accurate - after all - we are dealing with amounts of silica and
alumina plus the fluxes - it is not a case of being lucky.
There have been many times when a clay was no longer available or dropped
for other reasons - I have had to find a replacement clay and substitute it
in - and get the same absorbency and colour and shrinkage - most of the
time I can do it in one try - maybe two - at most three.
In the old days - we had to guess - and finding the right mix could go on
forever.
I'm interested in how you do this!
My name is Ron by the way - best regards - RR
>Hello Roy. It is not that calculations can not be used for clay bodies, far
>from it. It is just that it is invalid to apply glass theory to bodies.
>These assume the complete melting of all components to form a glass, where
>as bodies are composed of glass and crystalline phases that never melted.
>You are fortunate to have achieved success by using unity formulae for
>bodies, but why use this method when other more appropriate methods are
>available?
>
>Thomas
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Thomas Malone on mon 26 mar 07
On Sun, 25 Mar 2007 13:11:40 -0500, Ron Roy wrote:
>Hi Thomas,
>
>Perhaps we are not talking about the same thing - are you saying calculated=
>expansion is no good for bodies? - if so I would agree.
>
>I have to assume you have not used the method to "fix" clay bodies - I also=
>use % analysis as a quick check after I have used unity - but always start
>with unity and only a few time find it necessary to alter after I look at
>the analysis.
>
>I monitor the clays for a local clay company and adjust them on a regular
>basis to correct for shrinkage and absorbency - I have found the results to=
>be very accurate - after all - we are dealing with amounts of silica and
>alumina plus the fluxes - it is not a case of being lucky.
>
>There have been many times when a clay was no longer available or dropped
>for other reasons - I have had to find a replacement clay and substitute it=
>in - and get the same absorbency and colour and shrinkage - most of the
>time I can do it in one try - maybe two - at most three.
>
>In the old days - we had to guess - and finding the right mix could go on
>forever.
>
>I'm interested in how you do this!
>
>My name is Ron by the way - best regards - RR
>
>>Hello Roy. It is not that calculations can not be used for clay bodies,
far
>>from it. It is just that it is invalid to apply glass theory to bodies.
>>These assume the complete melting of all components to form a glass, where=
>>as bodies are composed of glass and crystalline phases that never melted.
>>You are fortunate to have achieved success by using unity formulae for
>>bodies, but why use this method when other more appropriate methods are
>>available?
>>
>>Thomas
>
>Ron Roy
>RR#4
>15084 Little Lake Road
>Brighton, Ontario
>Canada
>K0K 1H0
>
>___________________________________________________________________________=
___
>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.
Hello Ron,
I would agree that calculating the thermal expansion of bodies is not worth
considering. But Seger (unity or molecular) formulae were devised for
glazes. Bodies are different as they are not fully melted, infact some
bodies such as earthenware contains very little glass. So what is the value
in calculating the amount of glass forming oxides?
I was surprised to see the suggestion of using unity formulae for bodies as
this is not taught in academia, nor is it used in industry. The method used
is, from my earlier reply to Dave: =93Calculations based on the chemical
analysis, or even better combined with the mineral content, is the most
appropriate method. These are not difficult, although obtaining the
necessary analyses maybe, but these would be needed to attempt a unity
formula calculation anyway. (Responsible suppliers generally provide this
information, albeit often typical values rather the actual of each batch.)
And to clarify: a chemical analysis would be the percentage of
the =91classical=92 oxides of SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, K2O, Na2O =
and
the Loss on Ignition. The mineral content would be the percentage of the
minerals present, such as kaolinite, montmorillionite, various feldspars,
various micas, quartz.=93
Sorry about my misunderstanding with you name.
Thomas
Matthew Katz on wed 28 mar 07
Hi,
Ron, I would be extremely careful about recommending using Unity Molecular
Formula for clay batches.
The UMF is designed with the sole purpose of reflecting the melting behavior
of glasses. Glasses that are composed of High levels of fluxes, blended
between RO and R2O. Where as fired high temperature bodies, the more
important factors are Mullite formation, Free quartz and Glass Content. It
is impossible to calculate the Free quartz and mullite which are what truly
dictate fired performance with the UMF. Beside the fact that the glasses
that are formed in Bodies are completely different that the glasses formed
by glazes. Also Using the UMF for Clay substitution will tell you nothing.
To do that competently you really need, Chemical analysis, and Morphology
data (Clay particle shapes).
We use a completely different calculation method, that we have written into
a spreadsheet. It is still extremely rough around the edges for public
consumption, but I am working on a draft that hopefully we will be able to
release soon. It will create a new "UMF" for Clays.
As far as the disclosure, hopefully we can change that together. We are in
the process of creating a new clay company with complete disclosure. We
believe that there is no reason to hide your formulas. If the companies are
hiding their formulas because they are afraid of the competition, they
should make better products. Because in the end it is true that you are
responsible for your final outcome, but your materials have a heck of a lot
to do with it too.
Knowledge benefits us all.
Best,
Matt
Hi Thomas,
Perhaps we are not talking about the same thing - are you saying calculated
expansion is no good for bodies? - if so I would agree.
I have to assume you have not used the method to "fix" clay bodies - I also
use % analysis as a quick check after I have used unity - but always start
with unity and only a few time find it necessary to alter after I look at
the analysis.
I monitor the clays for a local clay company and adjust them on a regular
basis to correct for shrinkage and absorbency - I have found the results to
be very accurate - after all - we are dealing with amounts of silica and
alumina plus the fluxes - it is not a case of being lucky.
There have been many times when a clay was no longer available or dropped
for other reasons - I have had to find a replacement clay and substitute it
in - and get the same absorbency and colour and shrinkage - most of the
time I can do it in one try - maybe two - at most three.
In the old days - we had to guess - and finding the right mix could go on
forever.
John Britt on wed 28 mar 07
Matt,
You're the man! Now we are getting somewhere.
You get a honorary membership into the "Glaze-Free Trade Society". But we
will have to rename it the Clay and Glaze-Free Trade Society. That
actually sounds much better. I will bring that up with our "committee"
for swift passage.
Keep it coming dude,
John Britt
www.johnbrittpottery.com
Ron Roy on thu 29 mar 07
Hi Thomas,
Well I am surprised that you do not see how unity can be used - it is based
on chemical analysis for starters.
It does give proportions of alumina, silica and the fluxes. You can even
put unity on alumina if you prefer that way. I use it mainly for vitrified
bodies by the way - I do not find it so useful for the earthenware clays.
The clay company I work for tests all batches of clay for shrinkage and
absorbency so I have records going back over twenty years so I have lots of
data to back up my success.
I also have a dilatometer - the surprising thing about this is how
successful it has been.
As I said - I have been using it successfully for many years so it is
simply wrong to say it does not work.
RR
>Hello Ron,
>
>I would agree that calculating the thermal expansion of bodies is not worth
>considering. But Seger (unity or molecular) formulae were devised for
>glazes. Bodies are different as they are not fully melted, infact some
>bodies such as earthenware contains very little glass. So what is the value
>in calculating the amount of glass forming oxides?
>
>I was surprised to see the suggestion of using unity formulae for bodies as
>this is not taught in academia, nor is it used in industry. The method used
>is, from my earlier reply to Dave: =93Calculations based on the chemical
>analysis, or even better combined with the mineral content, is the most
>appropriate method. These are not difficult, although obtaining the
>necessary analyses maybe, but these would be needed to attempt a unity
>formula calculation anyway. (Responsible suppliers generally provide this
>information, albeit often typical values rather the actual of each batch.)
>And to clarify: a chemical analysis would be the percentage of
>the =91classical=92 oxides of SiO2, Al2O3, Fe2O3, TiO2, CaO, MgO, K2O, Na2O=
and
>the Loss on Ignition. The mineral content would be the percentage of the
>minerals present, such as kaolinite, montmorillionite, various feldspars,
>various micas, quartz.=93
>
>Sorry about my misunderstanding with you name.
>
>Thomas
>
>___________________________________________________________________________=
___
>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
Thomas Malone on fri 30 mar 07
Hello Ron,
I do see how unity can be used, and that it is based on chemical analyses
(the later istself is a shortcoming). But this does not mean it is a valid
technique. It is imposing glass theory on systems that are polycrystalline
with only limited glass phases; and this is incorrect.
As I noted before you have been fortunate to have found success with it,
and that I was surprised to see this suggestion as I have never previous
known it to be considered in either industry or academia.
Additionally such an approach perpetuates the belief, that is quite widely
held, that raw materials are simply collections of oxides. This can be seen
in suggestions that substitutions can be made just by achieving matches to
the main oxides (of which less than 8 are normally listed.)
John Hesselberth on fri 30 mar 07
On Mar 30, 2007, at 3:08 PM, Thomas Malone wrote:
> But this does not mean it is a valid
> technique. It is imposing glass theory on systems that are
> polycrystalline
> with only limited glass phases; and this is incorrect.
Hi Thomas,
I should probably know enough to stay out of this, but I won't. While
you are technically correct, Ron has been using unity as a tool in
clay body formulation successfully for 20 or so years. The clays he
formulates (and Tucker Clay mixes and sells) are respected as being
some of the finest available in North America if not the world. The
quality control and consistency he maintains year to year with ever
changing raw materials is the best in the world of studio potter
materials. His bodies are so much better than many of the other
commercially available bodies that people have them shipped hundreds
of miles to have access to them. Tell me of another clay body
manufacturer that has that kind of reputation.
Seems to me that makes it a pretty valid technique. It just works.
Maybe others should learn from Ron instead of trying to insult him by
telling him he shouldn't be using what works. And maybe, just maybe,
the theory needs revising based on new knowledge.
Regards,
John
Ron Roy on sun 1 apr 07
Hello again Matt,
Well - as I said I have been using the UMF for years now and the results
have been very useful - I feel I should say spectacular because of how it
has helped me. I hasten to add that testing every batch of clay made and
raw clays as they arrive also is a huge help.
I also have a dilatometer and that has been a big help in controlling
quartz and cristobalite.
Comparing bodies with each other is also most revealing.
I am only an hours drive from you - I can come and show you how it works. I
am also interested in your clay projects and your version of body UMF.
Let me know if you have time to share experiences.
RR
>Hi,
>Ron, I would be extremely careful about recommending using Unity Molecular
>Formula for clay batches.
>The UMF is designed with the sole purpose of reflecting the melting behavior
>of glasses. Glasses that are composed of High levels of fluxes, blended
>between RO and R2O. Where as fired high temperature bodies, the more
>important factors are Mullite formation, Free quartz and Glass Content. It
>is impossible to calculate the Free quartz and mullite which are what truly
>dictate fired performance with the UMF. Beside the fact that the glasses
>that are formed in Bodies are completely different that the glasses formed
>by glazes. Also Using the UMF for Clay substitution will tell you nothing.
>To do that competently you really need, Chemical analysis, and Morphology
>data (Clay particle shapes).
>We use a completely different calculation method, that we have written into
>a spreadsheet. It is still extremely rough around the edges for public
>consumption, but I am working on a draft that hopefully we will be able to
>release soon. It will create a new "UMF" for Clays.
>
>As far as the disclosure, hopefully we can change that together. We are in
>the process of creating a new clay company with complete disclosure. We
>believe that there is no reason to hide your formulas. If the companies are
>hiding their formulas because they are afraid of the competition, they
>should make better products. Because in the end it is true that you are
>responsible for your final outcome, but your materials have a heck of a lot
>to do with it too.
>Knowledge benefits us all.
>Best,
>Matt
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Matthew Katz on sun 1 apr 07
Hi Ron,
We would love to have you come by, although the distance it a little more
like 2+ hours, as I constantly have to tell my self when I ask "Why do I
live in the middle of nowhere?" For comparison, we are about 4 hours from
Toronto. and 2 hours form Buffalo.
Well the good news is that I am always here, but if you want to meet with
Bill as well, you may need to coordinate with him. I can't keep track of his
jet setter schedule. As the end of the semester is rapidly approaching,
summer break is always a good time, although it is also more time that Bill
is out of the office, traveling.
So let us know and we would love to have you down.
Best,
Matt
Ps. I would agree that testing every batch is a huge help for determining
fired properties. we just like to do that work on the front end too, to be
sure ; )
On 4/1/07, Ron Roy wrote:
>
> Hello again Matt,
>
> Well - as I said I have been using the UMF for years now and the results
> have been very useful - I feel I should say spectacular because of how it
> has helped me. I hasten to add that testing every batch of clay made and
> raw clays as they arrive also is a huge help.
>
> I also have a dilatometer and that has been a big help in controlling
> quartz and cristobalite.
>
> Comparing bodies with each other is also most revealing.
>
> I am only an hours drive from you - I can come and show you how it works.
> I
> am also interested in your clay projects and your version of body UMF.
>
> Let me know if you have time to share experiences.
>
> RR
>
> >Hi,
> >Ron, I would be extremely careful about recommending using Unity
> Molecular
> >Formula for clay batches.
> >The UMF is designed with the sole purpose of reflecting the melting
> behavior
> >of glasses. Glasses that are composed of High levels of fluxes, blended
> >between RO and R2O. Where as fired high temperature bodies, the more
> >important factors are Mullite formation, Free quartz and Glass Content.
> It
> >is impossible to calculate the Free quartz and mullite which are what
> truly
> >dictate fired performance with the UMF. Beside the fact that the glasses
> >that are formed in Bodies are completely different that the glasses
> formed
> >by glazes. Also Using the UMF for Clay substitution will tell you
> nothing.
> >To do that competently you really need, Chemical analysis, and Morphology
> >data (Clay particle shapes).
> >We use a completely different calculation method, that we have written
> into
> >a spreadsheet. It is still extremely rough around the edges for public
> >consumption, but I am working on a draft that hopefully we will be able
> to
> >release soon. It will create a new "UMF" for Clays.
> >
> >As far as the disclosure, hopefully we can change that together. We are
> in
> >the process of creating a new clay company with complete disclosure. We
> >believe that there is no reason to hide your formulas. If the companies
> are
> >hiding their formulas because they are afraid of the competition, they
> >should make better products. Because in the end it is true that you are
> >responsible for your final outcome, but your materials have a heck of a
> lot
> >to do with it too.
> >Knowledge benefits us all.
> >Best,
> >Matt
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
>
> ______________________________________________________________________________
> 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.
>
--
Matthew Katz
Alfred, NY
Ron Roy on sun 1 apr 07
Hi Tom,
It's just a way of counting oxides the way I use it for clays - but I also
use it that way for glazes.
When I compare clays I can see what will raise the maturing temperature and
what will lower it - mostly concentrating on alumina.
I'm not saying that is all there is to it mind you - I have enough
understanding of the raw materials to take into account shrinkage and how
crystals of silica affect CTE. Keeping an eye on iron content allows the
duplication of colour as well.
I have done this several times now - subbing in new clays for those that
are discontinued or no longer desirable for one reason or another. The
really interesting part is how close the dilatometer charts are from one
version to another.
I would be happy to compare it to the system you use!
RR
>Hello Ron,
>
>I do see how unity can be used, and that it is based on chemical analyses
>(the later istself is a shortcoming). But this does not mean it is a valid
>technique. It is imposing glass theory on systems that are polycrystalline
>with only limited glass phases; and this is incorrect.
>
>As I noted before you have been fortunate to have found success with it,
>and that I was surprised to see this suggestion as I have never previous
>known it to be considered in either industry or academia.
>
>Additionally such an approach perpetuates the belief, that is quite widely
>held, that raw materials are simply collections of oxides. This can be seen
>in suggestions that substitutions can be made just by achieving matches to
>the main oxides (of which less than 8 are normally listed.)
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Thomas Malone on mon 2 apr 07
Hello John,
You said =93trying to insult him.=94 Please could you explain where I have
insulated anyone? I simply observed that applying a Seger formula to a body
is not appropriate.
Seger formulae are for describing glasses. Bodies are not glasses, they are
polycrystalline solids with, depending on formulation and firing
conditions, varying amounts of glass. Thus it is not possible to describe
these using a glass model. It may, however, be possible to use the values
of the raw materials in a Seger calculation, but this would be nothing more
than a mathematical problem. It does not mean it is valid (and not wishing
to sound as harsh as it may do, a Seger calculation can be performed with
random numbers.) It is simpy not possible to ascribe a Seger formula to a
body as, to repeat, this describes glasses alone.
I am not surprised that control using Seger formulation can help ensure
consistency. This would be the result of monitoring and control techniques,
just as purchasing raw materials from recognised suppliers who sell their
products against specifications rather than digging any material from the
ground. But this does not prove a Seger formula is appropriate for a body.
And I guess this may sound insulating, although I do not intend it to be,
to suggest =93just maybe, the theory needs revising based on new knowledge=94=
is edging very close to Cargo Cult Science.
Trying to define a body using a Seger formula is: (1) scientifically
invalid. (2) even if valid would be overly simplistic tells one nothing
about other properties such as the mineralogy, particle sizes, particle
size distribution, particle morphology, surface area, methylene blue index,
modulus of rupture, plasticity, rheological properties. (3) encourages the
belief that raw materials are just a collection of oxides.
Even if a purely chemical view was wanted why use a Seger formula at all
when calculations using XRF analysis are not only not difficult, but are
scientifically valid?
You claim as =93respected as being some of the finest available in North
America if not the world.=94 That is a pretty big claim! But that is your
opinion, though I would suspect it could not be substantiated. I am not
looking to criticise one companys bodies, nor promote any other. What I do
know though is the tight control of raw materials and bodies is practised
world wide: from individual makers, to small operations making a few
hundred tonnes per year to large operation making thousands of tonnes per
week; reliable and consistent raw materials and bodies are found. None I
know of use Seger formulae for their bodies.
Again it s a very big claim to say that =93are so much better than many of
the other commercially available bodies that people have them shipped
hundreds of miles to have access to them.=94 Also how does distance relate t=
o
being better? Where I have worked material has been exported across
continents, so would these thousands of miles make for better products than
hundreds of miles?
I am very new to Clayart but have been surprised by the reception given to
myself, and others: I replied to a question saying that Seger (Unity)
formulae were not appropriate for bodies, which has led to accusations that
I am insulting people. This is similar to what I have read on the recent
subjects of plasticity and wet mixing of raw materials. Nothing in the
messages about Seger formulae, plasticity or wet mixing is new, and nothing
should be controversial. All this is established knowledge with (1) the
scientific study of ceramics goes back to at least Josiah Wedgwood, d 1795,
(2) Hermann Seger and his glass studies, d 1893 (3) the study of plasticity
by Bingham & Scott Blair from the turn of the 20th century, (4) published
works dates back over 100 years, and (5) the proven benefit of wet mixing
is hundreds of years old.
Is this normal Clayart etiquette? As I am not looking to insult or be
disrespectful to anyone. Thomas
Craig Martell on mon 2 apr 07
Thomas was saying:
>You said "trying to insult him." Please could you explain where I have
>insulated anyone? I simply observed that applying a Seger formula to a body
>is not appropriate.
Hello Thomas:
For what it's worth, I didn't think you insulted anyone. It's good that
you posted your thoughts about the use of the Seger Formula. It made me
think about it's use and so I proposed a question to Clayart and Matthew
Katz answered my query and now I know where the distinction is made
regarding crystalline forms of clay, or glaze.
regards, Craig Martell Hopewell, Oregon
Edouard Bastarache Inc. on mon 2 apr 07
Hello Craig,
once I used the Seger method to formulate a clay
body.
As a starting point, I used the chemical analysis
of Plainsman's H-440 and proceeded in the usual
manner using raw materials I had in my lab.
Since H-440 was slighlty granular, I added 10%
fine grog and ended up with a better-throwing
clay than the original.
"Trial and error" is also a way to go for
intuitive
people.
Later,
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
http://www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.orange.fr/smart2000/livres.htm
http://www.pshcanada.com/Toxicology.htm
http://www.ceramique.com/cerambooks/rayons/technologie.php
http://www.flickr.com/photos/30058682@N00/
Matthew Katz on mon 2 apr 07
All high temperature bodies (porcelain and stoneware over cone 5/6) , when
fired convert to a combination of Mullite(5-30%) Glass (50+%) remaining is
any unmelted quartz and fillers (ie. grog). Low temperature bodies, are
fired too low to form mullite, so basically what happens is that the fluxes
create just enough to keep all of the clay together and densify slightly and
calcine.
I can't speak for Egyptian paste and other specialty bodies.
On 4/2/07, Lee Love wrote:
>
> Aren't some claybodies "glass-like"? I recall doing lookups about
> the origins of Majolica and seeing early Egyptian pots that looked
> more like glass than pottery.
>
>
> Lee in Mashiko, Japan
>
>
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--
Matthew Katz
Alfred, NY
Lee Love on tue 3 apr 07
Aren't some claybodies "glass-like"? I recall doing lookups about
the origins of Majolica and seeing early Egyptian pots that looked
more like glass than pottery.
Lee in Mashiko, Japan
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