Ian Currie on tue 28 may 02
Hi Lawrence
I realise that our conclusions depend on our own research and observations,
but I believe your move to alter the sampling to remove the higher
concentration of sampling in corner C is a mistake.
The bunching up that you mention is (as I know you know) the result of
plotting line blends (where the line represents equal steps in weight)
plotting it onto a graph where the 2 axes are alumina and silica molecular
parts from the Seger formula. The mathematical cause is the arbitrary
(good) decision to keep the fluxes at unity.
It is true that there is sometimes a sudden jump between columns 4 and 5,
but one can usually see what the intermediate result will be... things
change in a predictable way in the high silica side (also the high alumina
side). My experience is that corner C, the high flux corner, is the corner
where you NEED extra sampling. Certainly it may sometimes look all the
same if Corner C is underfired, or overfired and very runny. However if you
get the firing "right" for Corner C then things change quickly from glaze to
glaze. To see an example of this, see page 80 in "Revealing Glazes", the
partial grid in the bottom left. You can see glaze C, (glaze 31) changing
radically as you move to the right adding in silica. It needs more, not
less, sampling.
I realise that you have worked out a very clever way of doing the blending
is such a way that equal steps on the alumina/silica graph are produced, but
in spite of what your student is telling you, I maintain that we need more,
not less sampling in Corner C, which is the wild and unpredictable corner.
As you move away from Corner C (by increasing alumina and silica) things
become more stable and predictable. This is one thing the alumina and
silica do.
Some time ago in developing this method I came to terms with diagrams and
graphs that were not neat. There is a tendency in all of us to want our
diagrams to be nice and symmetrical and balanced. But I can show you any
number of examples where the last thing you want is a line blend that is
equal steps on a Seger based graph. About 30 years ago I started out with
an experiment in a Japanese text book (which was a variant on an experiment
that goes back probably over 100 years in Europe) and I have gradually
modified that to give me the best return for the input of labour. I have
been criticised elsewhere for not using a triaxial format - and true, my
biaxial blend is a part of the larger flux/kaolin/silica triaxial. I prefer
this 4 glaze blend because it gives the simplest way of producing most of
the glazes that melt and the minimun that do not, while maintaining a
standardised system. [There are GREAT benefits to using this standardised
system.] I have systematically tailored the method to give the best
experimental coverage with a minimum of work in a standardized approach.
As an old Seger formula junkie (reformed) myself, I love to look at one of
the Matrix diagrams that plots it all out for you. But one of the great
advantages of the standard grid method is that you don't need to use a
computer. You and I both do of course, but many people prefer not to.
Lawrence, I think I need to do a lecture tour of NZ, so we can check out
each others' test tiles! What about an invite to Otago Polytechnic for a
start? I'm serious! It's a damn sight closer than the US (I'm currently
putting together my 7th US tour) and if Kiwi's are half as friendly as folk
in the US I'll have a GREAT time. And we BOTH might learn something....
:)
Incidenally... I just went to the web page you list below and could not see
the effect you mentioned... I DEFINITELY need to visit and see these tests
in the flesh! And please tell your student nice work!! And if you try sets
that are not so high in feldspar you will start to see more dramatic
examples of big jumps between samples... as your starting point (corner C)
has much less alumina and silica. By the way, do you ever use grid tiles?
Warm regards
Ian
http://ian.currie.to/
> While we are on the subject of Currie Recipe Grids, recently a student of
> mine drew our attention (yet again) to the fact that the method Ian uses
for
> generating the recipes in the grid produces a non-symetrical map of glazes
> in terms of the mol. parts of Al2O3 and SiO2. When the unity formula
values
> for the grid recipes are plotted on an Al2O3 SiO2 graph the values bunch
up
> in the C corner.
>
> The effect of this bunching up can produce considerable differences in
> glazes particularly between column 4 and 5 and in rows 1 and 2 while
glazes
> around Corner C can be very similar. We have a recipe grid displayed on
the
> Matrix2000 website which shows the effect of this bunching up.
>
> http://www.matrix2000.co.nz/TinaLuxBlend/TinaLuxQuad.htm
>
> Has anyone else using Currie Recipe Grids noticed this?
>
> Some senior students have been experimenting with a design which will
result
> in a more even distribution. I am still working on a computer model for
this
> in Matrix. We have not fired any of grids based on the new model yet but
> will post the results when we have.
>
> Cheers,
>
> Lawrence Ewing
>
> Senior Lecturer
> School of Art
> Otago Polytechnic
> Dunedin
> New Zealand
>
> email: lewing@clear.net.nz
> url: http://www.Matrix2000.co.nz
Ian Currie on tue 28 may 02
Hi Lawrence
> I hope to perhaps offer a third alternative which would create a
symetrical
> distribution in terms of the Al2O3 and SiO2 mols for those who wish to
> experiment with another approach.
Sounds like a great idea. I am passionately FOR choice.
> Far from being "clever" the method of creating a symetrical (mol parts)
grid
> is actually very logical and simple.
Um... I still think it's clever. No irony at all, just clever.
> Our aim is usually to
> initially fire to the same temperature as the base glaze.... after all we
> want to look at variations on the base glaze theme.
The way I use the grid for research there is no "correct" temperature for a
set. There are better or worse temperatures for individual glazes in the
set, but one of the advantages of using grid tiles (instead of individual
samples) is it makes it easy to produce lots of replication sets that can
be fired in a range of conditions. Different glazes come to fruition at
different temperatures or with other different firing conditions. Similarly
the grid tile facilitates research into different clay bodies.
> Creating recipe grids of any type does not require a computer.
Agreed, but the grid method allows the generation of an alumina/silica chart
of glazes, arguably the central and most important and fruitful experiment
in understanding glazes, and it allows one to do this without knowledge of
Seger formula or any more than the most basic of glaze chemistry. First
done probably over a hundred years ago using a Seger formula approach. My
own variation was originally Seger based, but after doing enough I was able
to simplify and standardise the method so anyone could use the method for
their own research using nothing more than recipes.
> In addition to this Matrix creates a unity formula for each of the
> individual recipes in the blend providing the opportunity to look at
> patterns from the unity formula perspective.
And I love this!
> Ian one of the problems with the promotion of a "Standard Approach" in any
> field is the possible suppression of creative thinking... the
consideration
> of alternatives.
Anyone who knows me Lawrence will know suppression of creative thinking is
anathema to me. The main reason for standardising the method was to make it
possible for beginners who have a real problem with chemistry or maths to be
able to design their own alumina/silica grids. To give them access to this
powerful experiment. If I have any secret agenda it is that I know once
enthusiastic people see how this works they will want to look further and
will more than likely get into the harder stuff (and it's really not that
hard) like Seger formula. And of course glaze calculation programmes like
Matrix and others make it SO easy. In MY day we had to calculate on a
cardboard abacus while crushing feldspar nodules with our teeth! :)
> Whichevers system is used recipe grids based on clay / silica variations
are
> enormously valuable. Why not consider extending the use of this tool
rather
> than restricting its use.
I wouldn't want to restrict this sort of exploration for a moment. But if
you or one of my students sought my opinion, I would say that based on
having seen many different grids fired on many clays under a wide range of
conditions.... I would say that on average the current arrangement is
definitely better. However I would add that sometimes you might need to do
one or two intermediate glazes (in between the current 35), and that would
mostly be around Corner C, sometimes between columns 4 and 5 (the high
silica side) and rarely in the high alumina corner. And when dealing with a
new set, there is no way to predict this.
And that is how I would handle it... occasional intermediate blends within
the existing system.
Most of my friends who use this method invent their own variations... they
do not use the "standard" grid method. However for beginners I believe it
is the best way.
The one thing I like better than winning an argument is losing one. Because
then I learn something, and that is exciting! Go for it! I look forward to
seeing the results... when you invite me over to Otago. Did I miss your
invitation??
Cheers
Ian
http://ian.currie.to/
Bruce Girrell on tue 28 may 02
Ian Currie wrote:
> > Ian one of the problems with the promotion of a "Standard
> Approach" in any
> > field is the possible suppression of creative thinking... the
> consideration
> > of alternatives.
>
> Anyone who knows me Lawrence will know suppression of creative thinking is
> anathema to me.
Indeed, one of the strong points of Ian's method in contrast to the glaze
calculations is that the tile often reveals very interesting glazes far
outside the "good glass" limits that are used in the glaze calc programs.
Currie's grid method _encourages_ creative thinking.
Bruce Girrell
Lawrence Ewing on tue 28 may 02
Hi Ian,
Thank you for your extensive and thorough response.
First can I reassure you that I have no intention of replacing your system
in Matrix with another. I am interested in offering alternative ways of
"killing the cat" so to speak so that others can explore and choose.
At present Matrix offers two 5 x 7 recipe grid construction alternatives:
1. using kaolin as per your system
2. using the clay existing in the base recipe
I hope to perhaps offer a third alternative which would create a symetrical
distribution in terms of the Al2O3 and SiO2 mols for those who wish to
experiment with another approach.
You said
> I realise that you have worked out a very clever way of doing the blending
> is such a way that equal steps on the alumina/silica graph are produced
Far from being "clever" the method of creating a symetrical (mol parts) grid
is actually very logical and simple. It reflects the method no doubt used
by many potters at some time of adding a material (say clay) to a base
recipe in regular increments. Applying this to the creation of the grid
corners:
C - is created by removing the clay and silica materials from the base
recipe and converting the recipe to total 100
A - is C + say 60% clay (clay added in 10% increments)
D - is C+ say 100% silica material (silica added in 25% increments)
B - is A+100% silica material
The difference between the approaches is that with your system Ian the
corner recipes are converted to 100% recipes while a symetrical Al2O3 and
SiO2 mol pattern emerges if the recipes are not manipulated to total 100.
The advantage I believe is that BOTH the progression of materials (clay and
Silica) AND the resulting Al2O3 and SiO2 mol parts are regular making this
kind of grid perhaps easier to create and assess without a computer than is
the Currie Grid.
You mentioned that the distribution in corner C is appropriate "if you get
the firing right". By this I presume that you mean that sometimes the grid
should be fired to a temperature different from that of the original glaze
to get wider differences in corner C. With a system which by default removes
clay and silica materials to create corner C we really do not know what to
expect in the C corner before the grid is fired. Our aim is usually to
initially fire to the same temperature as the base glaze.... after all we
want to look at variations on the base glaze theme.
>But one of the great advantages of the standard grid method
>is that you don't need to use a computer.
Creating recipe grids of any type does not require a computer. Computer
programs such as Matrix simply offer a quick method of generating corner
recipes and subsequent individual recipes in the grid (as does your
website). In addition to this Matrix creates a unity formula for each of the
individual recipes in the blend providing the opportunity to look at
patterns from the unity formula perspective.
Ian one of the problems with the promotion of a "Standard Approach" in any
field is the possible suppression of creative thinking... the consideration
of alternatives. I like to suggest to students that there is probably
another and perhaps better way of doing anything. While the differences
between your "Standard Recipe Grid" and one which generates even
distribution in mol part terms may be small the OPPORTUNITY to use either
has value and may just result in new light being thrown on the subject.
Whichevers system is used recipe grids based on clay / silica variations are
enormously valuable. Why not consider extending the use of this tool rather
than restricting its use.
Kind regards,
Lawrence
----- Original Message -----
From: "Ian Currie"
To:
Sent: Thursday, January 01, 1970 1:54 PM
Subject: Please Don't re-jig Corner C - was: Currie/too much work?
> Hi Lawrence
>
> I realise that our conclusions depend on our own research and
observations,
> but I believe your move to alter the sampling to remove the higher
> concentration of sampling in corner C is a mistake.
>
> The bunching up that you mention is (as I know you know) the result of
> plotting line blends (where the line represents equal steps in weight)
> plotting it onto a graph where the 2 axes are alumina and silica molecular
> parts from the Seger formula. The mathematical cause is the arbitrary
> (good) decision to keep the fluxes at unity.
>
> It is true that there is sometimes a sudden jump between columns 4 and 5,
> but one can usually see what the intermediate result will be... things
> change in a predictable way in the high silica side (also the high alumina
> side). My experience is that corner C, the high flux corner, is the
corner
> where you NEED extra sampling. Certainly it may sometimes look all the
> same if Corner C is underfired, or overfired and very runny. However if
you
> get the firing "right" for Corner C then things change quickly from glaze
to
> glaze. To see an example of this, see page 80 in "Revealing Glazes", the
> partial grid in the bottom left. You can see glaze C, (glaze 31) changing
> radically as you move to the right adding in silica. It needs more, not
> less, sampling.
>
> I realise that you have worked out a very clever way of doing the blending
> is such a way that equal steps on the alumina/silica graph are produced,
but
> in spite of what your student is telling you, I maintain that we need
more,
> not less sampling in Corner C, which is the wild and unpredictable corner.
> As you move away from Corner C (by increasing alumina and silica) things
> become more stable and predictable. This is one thing the alumina and
> silica do.
>
> Some time ago in developing this method I came to terms with diagrams and
> graphs that were not neat. There is a tendency in all of us to want our
> diagrams to be nice and symmetrical and balanced. But I can show you any
> number of examples where the last thing you want is a line blend that is
> equal steps on a Seger based graph. About 30 years ago I started out with
> an experiment in a Japanese text book (which was a variant on an
experiment
> that goes back probably over 100 years in Europe) and I have gradually
> modified that to give me the best return for the input of labour. I have
> been criticised elsewhere for not using a triaxial format - and true, my
> biaxial blend is a part of the larger flux/kaolin/silica triaxial. I
prefer
> this 4 glaze blend because it gives the simplest way of producing most of
> the glazes that melt and the minimun that do not, while maintaining a
> standardised system. [There are GREAT benefits to using this standardised
> system.] I have systematically tailored the method to give the best
> experimental coverage with a minimum of work in a standardized approach.
>
> As an old Seger formula junkie (reformed) myself, I love to look at one of
> the Matrix diagrams that plots it all out for you. But one of the great
> advantages of the standard grid method is that you don't need to use a
> computer. You and I both do of course, but many people prefer not to.
>
> Lawrence, I think I need to do a lecture tour of NZ, so we can check out
> each others' test tiles! What about an invite to Otago Polytechnic for a
> start? I'm serious! It's a damn sight closer than the US (I'm currently
> putting together my 7th US tour) and if Kiwi's are half as friendly as
folk
> in the US I'll have a GREAT time. And we BOTH might learn something....
> :)
>
> Incidenally... I just went to the web page you list below and could not
see
> the effect you mentioned... I DEFINITELY need to visit and see these
tests
> in the flesh! And please tell your student nice work!! And if you try
sets
> that are not so high in feldspar you will start to see more dramatic
> examples of big jumps between samples... as your starting point (corner C)
> has much less alumina and silica. By the way, do you ever use grid tiles?
>
> Warm regards
>
> Ian
> http://ian.currie.to/
>
>
>
>
>
>
> > While we are on the subject of Currie Recipe Grids, recently a student
of
> > mine drew our attention (yet again) to the fact that the method Ian uses
for
> > generating the recipes in the grid produces a non-symetrical map of
glazes
> > in terms of the mol. parts of Al2O3 and SiO2. When the unity formula
values
> > for the grid recipes are plotted on an Al2O3 SiO2 graph the values bunch
up
> > in the C corner.
> >
> > The effect of this bunching up can produce considerable differences in
> > glazes particularly between column 4 and 5 and in rows 1 and 2 while
glazes
> > around Corner C can be very similar. We have a recipe grid displayed on
the
> > Matrix2000 website which shows the effect of this bunching up.
> >
> > http://www.matrix2000.co.nz/TinaLuxBlend/TinaLuxQuad.htm
> >
> > Has anyone else using Currie Recipe Grids noticed this?
> >
> > Some senior students have been experimenting with a design which will
result
> > in a more even distribution. I am still working on a computer model for
this
> > in Matrix. We have not fired any of grids based on the new model yet but
> > will post the results when we have.
> >
> > Cheers,
> >
> > Lawrence Ewing
> >
> > Senior Lecturer
> > School of Art
> > Otago Polytechnic
> > Dunedin
> > New Zealand
> >
> > email: lewing@clear.net.nz
> > url: http://www.Matrix2000.co.nz
>
>
____________________________________________________________________________
__
> 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.
Ababi on wed 29 may 02
Hello Bruce
Glaze software has the limit tables that guides you to get the "proper"
glaze and helps you when you want to substitute a material.
. It is true. Yet, in some glaze programs you can make your own limits.
to guide you to do your desired direction. The glaze software in my
point of view gives me tool to predict directions not necessarily for
the "good and reliable glaze", though I have very low chemical as well
as mathematical understanding.
Ababi
---------- Original Message ----------
>Ian Currie wrote:
>> > Ian one of the problems with the promotion of a "Standard
>> Approach" in any
>> > field is the possible suppression of creative thinking... the
>> consideration
>> > of alternatives.
>>
>> Anyone who knows me Lawrence will know suppression of creative
>thinking is
>> anathema to me.
>Indeed, one of the strong points of Ian's method in contrast to the
>glaze
>calculations is that the tile often reveals very interesting glazes far
>outside the "good glass" limits that are used in the glaze calc
>programs.
>Currie's grid method _encourages_ creative thinking.
>Bruce Girrell
>_______________________________________________________________________
_
>______
>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.
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