Ron Roy on mon 24 may 04
Hi Fara,
It is so good to hear someone else vent about potters not wanting to know
about the science - now there are 4 of us.
It is such a waste - understanding something about the science of ceramics
has been probably the most interesting thing I have done in my life. I have
wondered - since I have become immersed in the science part - what were my
instructors thinking when they said it was a waste of time?
Re the crystals standing proud - after the glazes had been etched in acid -
the glaze between the crystals was attacked more (eaten away) than the
crystals.
It's one of the best books I have Fara - worth a look around for - maybe in
a library some where - or try the 2nd hand book sellers.
Ceramic Glaze Technology by Taylor and Bull
ISBN 0-08-033465-2 Hard cover
ISBN 0-08-033466-0 Flexicover cover
RR
>I was intrigued by your (Ron's) comment about etching and the
>tougher bit standing proud, so I just took my broken plate and
>put it under the microscope. Again I could see no difference
>between the two sides; nothing is standing proud -- or at least,
>any prouder than normal since the crystals do rise above and
>dip below the surface of the ground by a few micromilleters.
>So my question is ... well, I'm not sure if I've got a question
>or I'm just venting. I would like to see other folks' input
>on the issue of Science and Craft, I guess is what I mean to say.
>The above was mine. Have at it...
>Fa
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Fara Shimbo on mon 24 may 04
Hi Ron and Ivor and all,
On the issue of which is more durable in a crystalline glaze,
the crystal or the ground...
This is really, really hard to test. True the crystals do pull
some silica out of the glaze, but most recipes account for that
by adding extra silica. One way to test this is the Moh's
hardness. Zn2SiO4 has a hardness of 5.5 which means a knife or
fork will scratch it. I just tried that and it didn't work, crystals
or ground. What -will- scratch both very easily is rubbing against
a piece of porcelain which when fired to maturity. Porcelain can have a
Moh's hardness of 6 or 7. These are knife-proof hardnesses.
Even if you accept that Zn2SiO4 by itself is soft, if you color
it, you get (colorant)-zinc spinels (in very small quantities,
admittedly) mixed in with the Zn2SiO4. These are generally of
greater hardness than willemite alone.
I was intrigued by your (Ron's) comment about etching and the
tougher bit standing proud, so I just took my broken plate and
put it under the microscope. Again I could see no difference
between the two sides; nothing is standing proud -- or at least,
any prouder than normal since the crystals do rise above and
dip below the surface of the ground by a few micromilleters.
Now... all this leads me to something that *really* bugs me
about crystalline glazes in general and lots of ceramics in
particular. Since I published Crystal Glazes, and especially
with the second edition, the most often heard complaint about it
I've gotten is, "There's too much science in this book. Who
cares!" I even had one guy say, "Well, that does it. Now you've
taken all the fun out of the glazes. I'm going to do something
else now."
Oh, poor baby! My nose bleeds for him. Wait 'til he sees the
third edition! To my mind, you can't have enough science.
One of the things that attracted me to crystals (quite apart
from the fact that I am compulsively attracted to anything
sparkly) is that there is -so much- good science to be done
about them. To me, this is heaven. Every single pot I make is
an experiment of some kind. Sometimes my kilns are full of
nothing but experiments and no real pots at all.
To a lot of other people, the fact that there is -any- science
out there takes all the fun out of life. Science should stay
away from Craft and Art because Craft and Art are Talents and
science is drudgery.
On the other hand I get a lot of people on the BBS and at the
workshops who -want- to know the science because they want to
know everything about crystalline glazes. But I have a hard
time explaining things to them because they never took chemistry,
even in high school. To me this is overwhelmingly sad. I can
pull out a spectrometer and show them the brillant lines of
sodium in the flames from the top port of the gas kiln. They
are always impressed but not sure why they should be.
So my question is ... well, I'm not sure if I've got a question
or I'm just venting. I would like to see other folks' input
on the issue of Science and Craft, I guess is what I mean to say.
The above was mine. Have at it...
Fa
--
=============================================================
Fara Shimbo, Master Crystalliere, Certified Public Nuisance
-------------------------------------------------------------
Shimbo Pottery, PO Box 41, Hygiene, CO 80533 USA 720.207.5201
Crystalline-Ceramics.Info ShimboPottery.com Crystallieri.Org
Klysadel.Net TuranianHorse.Org
=============================================================
Ivor and Olive Lewis on tue 25 may 04
Dear Faro,
How wonderful to hear that you have a direct vision Spectrometer. So
have I. It is sufficiently discriminating to shoe the double sodium
line. Back in 1989 I used this to study the emissions which went up
the spout in a Salt Glaze firing. It was amazing to find that given
the richness of the atmosphere in the kiln that the Na lines were very
faint but there were several green and violet lines. We also made a
calibrated instrument as part of the practical work in the OU Science
Foundation Course.
There are many misconceptions as to the compass of Science. I suppose
the simple answer is, " Science provides the craft skills and the
intellectual skills to make intelligible the information provided by
our senses through answering the questions What? Where? When? Why? and
How? If we wish to know "Who", then we go back to recorded history or
read the list of Nobel Prize Winners for the past century.
With no more than a gas burner, some clean Nichrome wire, a few spots
of strong Hydrochloric acid and compounds of the 'Alkali Metal and
Alkali Earth Elements it is very easy to demonstrate what you have
shown people issuing from a kiln
Attitudes to Science are flavoured by the nature of the record. Real
thoughts are abstracted into symbols and turned into numbers which are
manipulated using strong mathematical insights that are difficult if
not impossible to express in plain language.
All members of Clayart can contribute to turning this tide of
negativity around by making sure they use the most simple language
available to describe events in the science of Ceramics. Remember
Ceramic Meringue?
Another example, when I was asked to teach science to a class which
was 80% young ladies. My vehicle for pursuing scientific knowledge was
Cosmetics. Now girls, how would you know if that "Blusher" was
contaminated with Arsenic?
Dear Lady, keep up the good work and pursue ceramic enlightenment.
Best regards
Ivor Lewis. Redhill, South Australia
Potters Council Member
----- Original Message -----
From: "Fara Shimbo"
To:
Sent: Monday, 24 May 2004 10:42
Subject: Science and Craft (was crystal bowls)
> Hi Ron and Ivor and all,
>
> On the issue of which is more durable in a crystalline glaze,
> the crystal or the ground...
>
> This is really, really hard to test. True the crystals do pull
> some silica out of the glaze, but most recipes account for that
> by adding extra silica. One way to test this is the Moh's
> hardness. Zn2SiO4 has a hardness of 5.5 which means a knife or
> fork will scratch it. I just tried that and it didn't work,
crystals
> or ground. What -will- scratch both very easily is rubbing against
> a piece of porcelain which when fired to maturity. Porcelain can
have a
> Moh's hardness of 6 or 7. These are knife-proof hardnesses.
>
> Even if you accept that Zn2SiO4 by itself is soft, if you color
> it, you get (colorant)-zinc spinels (in very small quantities,
> admittedly) mixed in with the Zn2SiO4. These are generally of
> greater hardness than willemite alone.
>
> I was intrigued by your (Ron's) comment about etching and the
> tougher bit standing proud, so I just took my broken plate and
> put it under the microscope. Again I could see no difference
> between the two sides; nothing is standing proud -- or at least,
> any prouder than normal since the crystals do rise above and
> dip below the surface of the ground by a few micromilleters.
>
> Now... all this leads me to something that *really* bugs me
> about crystalline glazes in general and lots of ceramics in
> particular. Since I published Crystal Glazes, and especially
> with the second edition, the most often heard complaint about it
> I've gotten is, "There's too much science in this book. Who
> cares!" I even had one guy say, "Well, that does it. Now you've
> taken all the fun out of the glazes. I'm going to do something
> else now."
>
> Oh, poor baby! My nose bleeds for him. Wait 'til he sees the
> third edition! To my mind, you can't have enough science.
> One of the things that attracted me to crystals (quite apart
> from the fact that I am compulsively attracted to anything
> sparkly) is that there is -so much- good science to be done
> about them. To me, this is heaven. Every single pot I make is
> an experiment of some kind. Sometimes my kilns are full of
> nothing but experiments and no real pots at all.
>
> To a lot of other people, the fact that there is -any- science
> out there takes all the fun out of life. Science should stay
> away from Craft and Art because Craft and Art are Talents and
> science is drudgery.
>
> On the other hand I get a lot of people on the BBS and at the
> workshops who -want- to know the science because they want to
> know everything about crystalline glazes. But I have a hard
> time explaining things to them because they never took chemistry,
> even in high school. To me this is overwhelmingly sad. I can
> pull out a spectrometer and show them the brillant lines of
> sodium in the flames from the top port of the gas kiln. They
> are always impressed but not sure why they should be.
>
> So my question is ... well, I'm not sure if I've got a question
> or I'm just venting. I would like to see other folks' input
> on the issue of Science and Craft, I guess is what I mean to say.
> The above was mine. Have at it...
>
> Fa
>
>
>
> --
> =============================================================
> Fara Shimbo, Master Crystalliere, Certified Public Nuisance
> -------------------------------------------------------------
> Shimbo Pottery, PO Box 41, Hygiene, CO 80533 USA 720.207.5201
> Crystalline-Ceramics.Info ShimboPottery.com Crystallieri.Org
> Klysadel.Net TuranianHorse.Org
> =============================================================
>
>
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Ellie Blair on tue 25 may 04
----- Original Message -----=20
From: Ron Roy=20
To: CLAYART@LSV.CERAMICS.ORG=20
Sent: Monday, May 24, 2004 11:44 PM
Subject: Re: Science and Craft (was crystal bowls)
It is so good to hear someone else vent about potters not wanting to =
know
about the science - now there are 4 of us.
You can add another to that list. I also do crystalline glazes and I =
feel that you can't really understand the process of this glazing =
technique unless you understand some of the science behind it. It is =
easy to make a pretty glaze but you need to understand the glaze and =
it's materials and how each interacts with the other under specific =
circumstances to make the glaze into something that is unexpected. It =
is important to learn the science of any glaze that you make rather it =
be on a functional pot or decorative one if you sell your work. With =
the worries of glaze toxicity on functional ware it seems important to =
know some science.
Ellie Blair
Ivor and Olive Lewis on thu 27 may 04
Dear Ellie Blair,
I have been mulling over your recent message (26 May)
You touch on a point I raised some time ago that there are other ways
of considering the nature of a glaze beside The Unity Formula or The
Recipe. Yes, we can make some predictions. From the Al2O3/SiO2 ratio
we can say things about glossiness or opacity or mattness, or from the
of R2O/SiO2+Al2O3 ratio we can predict maturity points and from the
molecular oxide proportions we can say if there will be crazing or
shivering problems. But this is not science, it is experience which
informs.
Speaking of crystalline glazes, you say "....I feel that you can't
really understand the process of this glazing technique unless you
understand some of the science behind it. It is easy to make a pretty
glaze but you need to understand the glaze and it's materials and how
each interacts with the other under specific circumstances to make the
glaze into something that is unexpected.....". Perhaps you could
elaborate on this using your experiences with Crystalline Glazes. Do
you have an example where your knowledge of the Science of Ceramics
enabled you to make a glaze into something unexpected?
By the way, I think we are in agreement that scientific knowledge is
important.
Best regards,
Ivor Lewis. Redhill, South Australia
Potters Council Member
Ron Roy on mon 31 may 04
Hi Ivor,
I'm seeking some clarification:
So are you saying that there is no science in Phase Diagrams - as they are
all compounded from actual testing?
If we apply understanding of the oxides and their effect on a glaze - are
we not using science?
RR
>I have been mulling over your recent message (26 May)
>You touch on a point I raised some time ago that there are other ways
>of considering the nature of a glaze beside The Unity Formula or The
>Recipe. Yes, we can make some predictions. From the Al2O3/SiO2 ratio
>we can say things about glossiness or opacity or mattness, or from the
>of R2O/SiO2+Al2O3 ratio we can predict maturity points and from the
>molecular oxide proportions we can say if there will be crazing or
>shivering problems. But this is not science, it is experience which
>informs.
>Ivor Lewis. Redhill, South Australia
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Ivor and Olive Lewis on tue 1 jun 04
Dear Ron Roy,
A good question > So are you saying that there is no science in
Phase Diagrams - as they are all compounded from actual testing? snip>.
Phase diagrams are the end product of processes used by Scientists who
have investigated material systems to find out how substances behave
when the conditions under which they exist are changed. The value of a
phase equilibrium diagram comes our ability to make predictions from
the information it contains. To do that we have to abide by the rules
used to prepare them and be able to read them.
In the field of Pottery, Phase Equilibrium Diagrams are being used to
predict melting events. Those who have reported on these predictions
either infer or assume that this information is described in terms of
compounds which are composed of Oxygen combined with another single
element, as Oxides. So they will look at a Phase Equilibrium Diagram,
see that it has a title naming three oxides in coded text
(Na2O-Al2O3-SiO2 for example), look at the table called a Unity or
Seger Formula which is an abstract representation of all of the
ingredients of a glaze and make assumptions about the melting point of
a mixture of oxides. Popular pottery culture tells us that if those
three oxides are present in the Abstract representation of the glaze
then that glaze recipe will melt at one of the low temperatures shown
in the Phase Equilibrium Diagram. Many writers who describe the
behaviour of glazes tell us this will happen. I need not name authors,
we have all read the books that make this prediction.
Now you have to answer the question, "Is this true in all instances".
If it is untrue in one single instance then the assumption is False.
The power of Scientific Theory lies not in our power of Proof but in
our ability to Test and Refute.
If we apply understanding of the oxides and their effect on a
glaze - are we not using science? No, we are not being
scientists, we are being technicians. We are using "Information" and
making assumptions about its validity.
Scientists make observations, propose hypotheses, test and revise. We
only take what has so far proved irrefutable, that which is consistent
in its ability to allow us to predict an outcome. As technicians, or
if you prefer the term, craftsmen it is the consistency of prediction
that allows us to be consistent in our work. The example I gave is of
this nature.
We should have a clear notion what the word Science means and we
should understand what the Discipline of Chemistry is about. At its
most simple, Science is a method of asking questions about Reality,
answering and testing our answers. The systematic way that is done is
via the Scientific Method. Putting those answers to useful purpose is
left to Technologists.
As I said, relating to our use of certain conclusions <... But this is
not science, it is experience which informs.>
Best regards,
Ivor Lewis. Redhill, South Australia
Potters Council Member
.
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