Lili Krakowski on sun 2 mar 08
Well, I guess I was not very clear. I meant to convey my total
skepticism about the use and merit of limit formulas.
I am not interested in floating blues, another ClayArter IS, and the
formula struck me because it was SO far outside the Alumina and Silica
"limits" for c.6.
May Luk's pantyhose chart analogy is excellent. And to a certain extent
makes my point. While the charts help some they generally do not solve the
problem. At least not for me. There are many variables in body shape that
are not "covered' by height and weight, and so while the chart points one in
a direction,
it does not do the job (At least not for dumpy little old
women!)
Ok. My point was, and I apologize for unclearness, that we are given these
limit formulas, which , as the years have gone by, I find pretty useless.
There
are SO many factors involved in a glaze that are not even hinted at. For
instance
phases; for instance lithium, magnesium, and all the opacifiers. The effect
of colorants. I do not know enough--ok I know zip--about whether slow and
controlled heating and cooling with "holds" would change the tolerance of a
glaze for certain materials, nor whether ballmilling a glaze would have any
effect.
B2O3, on which I always have a had a mad crush, is my best example of
a material that slithers from here to there. It is a glass former, but...it
lowers melting
temp of glaze, but is it a flux? (I do not think so.)
I can see the usefulness of COE limits, though I wonder whether the COE of
the glaze matters by itself, or whether it really should be correlated to
the
COE of the body. In other words, yeah, this glaze has COE X but will it
work
on a body with COE Y or Z?
Is there a glaze calculation program that would allow more "interchange" and
variation
than GlazeMaster (TM) which I have and love...but which has some "limits"!
Lili Krakowski
Be of good courage
John Post on sun 2 mar 08
Hi Lilli,
To continue with your pantyhose analogy...
While the size chart may not always tell you which size to purchase
initially, the chart might be useful after you tried on a pair that
didn't fit and then had to make another selection. The information
you got from the first pair coupled with the chart might help you to
make an informed decision about which size to try next.
I think that the usefulness from a limit formula comes into play after
you have tested a glaze and made a change or two to it. Then you can
see in which direction the numbers are going and study the results you
are getting. I prefer Ian Currie's grid method that shows you 35
variations of alumina and silica over a single tile. Instead of
adding clay or silica in small little increments to try and cure a
glaze problem, I like to see what happens when alumina and silica go
from as little as possible in the glaze until there is an overload.
Then you can examine the grid tile and see what effect a progression
of alumina or silica has on the glaze.
I don't like to look at the limit formula for a glaze before I test
it. I prefer to look at the numbers after as an explanation for what
is going on. The more numbers you have to look at, the more
information you have to draw inferences from. That's why Ian's grid
method is so powerful. In a 2-3 hour session you can create a grid to
serve as a "visual" starting point for understanding a glaze and the
numbers attached to it.
The map is not the territory.
The limit formula is not the glaze.
John Post
Sterling Heights, Michigan
http://www.johnpost.us :: cone 6 glaze website ::
http://www.wemakeart.org :: elementary art website ::
> Well, I guess I was not very clear. I meant to convey my total
> skepticism about the use and merit of limit formulas.
>
> May Luk's pantyhose chart analogy is excellent. And to a certain
> extent
> makes my point. While the charts help some they generally do not
> solve the
> problem. At least not for me. There are many variables in body
> shape that
> are not "covered' by height and weight, and so while the chart
> points one in
> a direction, it does not do the job (At least not for dumpy little
> old women!)
>
> Ok. My point was, and I apologize for unclearness, that we are
> given these
> limit formulas, which , as the years have gone by, I find pretty
> useless.
> Thereare SO many factors involved in a glaze that are not even
> hinted at. For
> instance phases; for instance lithium.....
> Is there a glaze calculation program that would allow more
> "interchange" and
> variation than GlazeMaster (TM) which I have and love...but which
> has some "limits"!
>
> Lili Krakowski
Ivor and Olive Lewis on mon 3 mar 08
Dear Lili Krakowski,=20
<a material that slithers from here to there. It is a glass former, =
but...it lowers melting temp of glaze, but is it a flux? (I do not think =
so.).>>
I am not sure if this is a rhetorical question...
..... But the answer would depend on defining "Flux" in the context of =
ceramic materials.
In a metallurgical context Borax and boric oxide most certainly are =
"Fluxes", since by definition they have the power to dissolve oxide =
scale from a metal surface so that molten metal such a tin/lead alloy =
will bond to a base metal such as copper, brass or steel.
In the Ceramic Context Robert Fournier defines a flux as ..."....an =
oxide, generally a base,which lowers the melting point of an acidic =
oxide, especially Silica. Boric oxide has an ambiguous position....."
The foolish question I would pose asks "When heating an intimate mixture =
of Sodium Carbonate and quartz powder, what makes us aware of the lower =
melting point of the quartz ?"
The system that would be of greatest interest because of our use of =
Calcium borate is B2O3-CaO-SiO2. This Phase diagram shows that there =
will be a region where two immiscible liquids exist. But translating =
this information into a working glaze recipe might be difficult.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
=20
Taylor Hendrix on mon 3 mar 08
Mama Lili,
I really like the ability to compare several glazes via their COE. As
I have only one clay body over which I glaze, I can compare a glaze
that fits quite well with an unknown glaze by checking their COE with
John's program (or any other program as well). The more "good" glazes
I have the better handle I have on my clay body's COE. It will remain
for me an unknown because I buy my clay by the box and I don't have my
own dialometer for testing.
This of course is John and Ron's very suggestion in their book.
What kind of interchange are you wanting with your glaze program?
Taylor, in Rockport TX
On 3/2/08, Lili Krakowski wrote:
...> I can see the usefulness of COE limits, though I wonder whether the COE of
> the glaze matters by itself, or whether it really should be correlated to
> the
> COE of the body. In other words, yeah, this glaze has COE X but will it
> work
> on a body with COE Y or Z?
>
> Is there a glaze calculation program that would allow more "interchange" and
> variation
> than GlazeMaster (TM) which I have and love...but which has some "limits"!
...
John Britt on mon 3 mar 08
John ,
You don=92t throw out the baby with the bath water.
The Currie Method is far more than a way to find functional glazes. It is
a way to =93understand=94 fluxes and glazes. I can think of no better way to=
see how a flux like magnesium oxide functions in a glaze than to try
Currie=92s method and study the Magnesium Oxide chapter in =93Stoneware
Glazes=94. This gives you a great overview of magnesium oxide over all the
cones at once, not just cone 6. It is an outstanding educational tool. The
participants actually learn to think and discover on their own.
It is also a great way to =93understand=94 firing cycles. As you know, he
always makes up multiple tiles for various firings and then looks at the
variations in the glaze.
You and Ron may be focused on functional glazes and leaching and I commend
you for that, but that doesn=92t mean that everyone else is nor does it mean=
that all learning should revolve around your narrow parameters. In fact,
someone could take the Currie workshop and achieve a greater understanding
of glazes and then simply apply your targets for functionality at cone 6.
John Britt
John Sankey on mon 3 mar 08
"I wonder whether the COE of the glaze matters by itself, or
whether it really should be correlated to the COE of the body"
The _only_ reason for checking COE is in comparison to the body.
Commercial clays have a fairly narrow range of expansions - it's
rare to find one outside 6.2 to 7.7 (cf.
http://web.archive.org/web/20050507131945/http://www.dhpot.demon.co.uk/crazing.htm)
So, if you have a glaze with COE under 5.5 or over 8.5, you can
definitely expect problems unless it is fluid when melted and
applied very thin.
"Instead of adding clay or silica in small little increments to
try and cure a glaze problem, I like to see what happens when
alumina and silica go from as little as possible in the glaze
until there is an overload."
Such a use of a grid has a major weakness - you are testing
glazes that shouldn't be used because they aren't stable.
Instead, you should be keeping silica and alumina within stable
limits, and varying other components that might have an effect on
the problem you are investigating.
In the case of COE, potassium is the most useful to raise COE,
and it strengthens the glaze at the same time
(http://sankey.ws/glazeexpansion.html#sr). Zinc lowers COE the
most. So, these should be the variables in your grid, not silica
and alumina.
If the problem is fluidity, alumina decreases it, boron increase
it, so these would be more useful variants.
In short, test your problem, not a blind formula.
John Sankey
----------
Include 'Byrd' in the subject line of your reply to get through my spam
filter.
I can only read text mail, no attachments.
May Luk on mon 3 mar 08
Hello fellow glaze testers;
I think Currie Grid is a great learning tool for beginners. The best way to=
learn glaze, at the end of the day, is to fire a lot and in different ways=
. Then it is a matter of observation and deduction, with or without limited=
formulae, graph plotting etc. Without the fired tiles, the analyses are ju=
st numbers and the recipes are just words - very limiting indeed.
MC6G is such an informative book, it is a shame that it is being used as a =
recipe book only. (I hope I am wrong on this one)
John H; Glazemaster and Currie Grid together is a beauty. I use them togeth=
er often. Because I think through my flux set before testing, I always get =
green squares from my Currie Grids. Nevertheless, it would be interesting t=
o pull out some =E2=80=98unstable=E2=80=99 glaze from the grid and test the=
m according to MC6G and perhaps, more interesting glazes can be added to th=
e stable pool.
Best Regards
May
Kings County, NY
P.S. I cannot get any analysis on my American clays (Standard 182, Grolleg =
Porcelain and Laguna B-mix). I can get analysis for Helmar but I cannot buy=
it because of my location. It seems like only Canadian and British Potters=
are the lucky recipients of clay analyses (& NHS!) Why? Because they pay V=
AT?
>>>>>>>>>>>>>>>>>>>>>>
"I wonder whether the COE of the glaze matters by itself, or
whether it really should be correlated to the COE of the body"
The _only_ reason for checking COE is in comparison to the body
>>>>>>>>>>>>>>>>>>>
Alisa Clausen on mon 3 mar 08
as unscientific as possible this sounds,
I test many glazes because initially, the most
important property of a glaze for me is
How does it look on my clay from my kiln?
When I see something I want to continue to fire, I go back and look at it
in a chemistry setting. Since I use Glaze Master and John and Ron have
personally taught me a lot, I go after their parameters when adjusting a
glaze I may have issues with, to try to iron out problems it may present.
(Albeit the best I can with my knowledge of materials to date).
I look at it as simple as the outside and inside beauty. Unlike people, a
beautiful glaze inside (the analysis/limits) does not outweigh an ugly
outside (how it looks). However, a beautiful outside is not completely
shallow, however, is limited perhaps in it's use on table ware. That is
why as understand more about materials and their influences, I try to get
a balance for the inner and outer beauty of a glaze I want to use.
There are different school's of thought for what the correct limits are
for a good analysis, but I think we must chose our schools according to
our individual understanding of what we want and how we want to achieve
that. Of course, this can also change at different times in our
development.
Best regards from Alisa in Denmark
The Goodsons on mon 3 mar 08
John,
Hello to you! I am still learning - so please bare with me while I ask
a few questions. The link is great, by the way, for the COE charts.
You state that
> Commercial clays have a fairly narrow range of expansions
Is there a place to find the expansion rates of the commercial glazes
like Laguna or Highwater? Do you know if they are published anywhere??
I have used the tests from Ron Roy and John Hesselberth' s book,
_Mastering Cone 6 Glazes_ to help narrow down the expansion of the clays
that I use most, but your post has me wondering if this is might be
printed somewhere or if the commercial clay companies make the expansion
rate of their clays known??
Also, what are potclays?? Are they from a particular company?? I don't
recognize any of the names.
Thanks for the information!!
Have a great day!
Linda Goodson
PS I am thinking that a "second" reason for checking the COE would be
if you are layering glazes, or using different glazes on the inside and
the outside of a piece.
John Sankey wrote:
> "I wonder whether the COE of the glaze matters by itself, or
> whether it really should be correlated to the COE of the body"
>
> The _only_ reason for checking COE is in comparison to the body.
>
> Commercial clays have a fairly narrow range of expansions - it's
> rare to find one outside 6.2 to 7.7 (cf.
> http://web.archive.org/web/20050507131945/http://www.dhpot.demon.co.uk/crazing.htm)
>
> So, if you have a glaze with COE under 5.5 or over 8.5, you can
> definitely expect problems unless it is fluid when melted and
> applied very thin.
>
> "Instead of adding clay or silica in small little increments to
> try and cure a glaze problem, I like to see what happens when
> alumina and silica go from as little as possible in the glaze
> until there is an overload."
>
> Such a use of a grid has a major weakness - you are testing
> glazes that shouldn't be used because they aren't stable.
> Instead, you should be keeping silica and alumina within stable
> limits, and varying other components that might have an effect on
> the problem you are investigating.
>
> In the case of COE, potassium is the most useful to raise COE,
> and it strengthens the glaze at the same time
> (http://sankey.ws/glazeexpansion.html#sr). Zinc lowers COE the
> most. So, these should be the variables in your grid, not silica
> and alumina.
>
> If the problem is fluidity, alumina decreases it, boron increase
> it, so these would be more useful variants.
>
> In short, test your problem, not a blind formula.
>
> John Sankey
> ----------
>
>
>
>
John Hesselberth on mon 3 mar 08
On Mar 3, 2008, at 9:01 AM, John Sankey wrote:
> Such a use of a grid has a major weakness - you are testing
> glazes that shouldn't be used because they aren't stable.
> Instead, you should be keeping silica and alumina within stable
> limits, and varying other components that might have an effect on
> the problem you are investigating.
This is my biggest concern with Currie's grid for functional potters.
Most of the samples end up being of a very unstable composition. I
have urged Ian to find a way to revise his method to make it more
useful for functional potters--that was a couple years ago and I
don't know if he has or not. As currently designed it is a useful
technique for the sculptural potter who wants to see a broad range of
possibilities. But the functional potter??--I certainly don't find it
useful.
The quadraxial blend layout in GlazeMaster will let you see this very
graphically. Put the 4 Currie compositions in the corners, set the
silica and alumina limits you want to stay within, and look at the
colored grid that results.
Regards,
John
John Hesselberth
http://www.masteringglazes.com
http://www.frogpondpottery.com
"I love everything that's old: old friends, old times, old manners,
old books, old wines." Oliver Goldsmith, "She Stoops to Conquer" (1773)
Taylor Hendrix on tue 4 mar 08
Hey May and John H,
John, am I wrong in thinking that a non-standard Currie grid would do
the trick? One simply replaces the two variables silica and alumina
with two other variables. Shouldn't be any harder.
May, I think both tools are fantastic together too, but I haven't had
the chance yet to have a go myself (yet). The grid just feels like a
fantastic way for beginner glaze makers to understand how the
materials work together. Throw in Hopper's suggestion to make fusion
buttons of single materials and a beginner would have three great ways
to teach her or himself how things really work.
I am glad that John's glaze program has a quick visual way of seeing a
Currie grid through the eyes of a particular limit range as well.
Taylor, in Rockport TX
On 3/3/08, May Luk wrote:
...
> MC6G is such an informative book, it is a shame that it is being used as a recipe book only. (I hope I am wrong on this one)
>
> John H; Glazemaster and Currie Grid together is a beauty. I use them together often. Because I think through my flux set before testing, I always get green squares from my Currie Grids. Nevertheless, it would be interesting to pull out some 'unstable' glaze from the grid and test them according to MC6G and perhaps, more interesting glazes can be added to the stable pool.
>
> Best Regards
> May
On 3/3/08, John Hesselberth wrote:
...
> This is my biggest concern with Currie's grid for functional potters.
> Most of the samples end up being of a very unstable composition. I
> have urged Ian to find a way to revise his method to make it more
> useful for functional potters--that was a couple years ago and I
> don't know if he has or not.
...
John Hesselberth on wed 5 mar 08
On Mar 4, 2008, at 3:38 PM, Taylor Hendrix wrote:
> John, am I wrong in thinking that a non-standard Currie grid would do
> the trick? One simply replaces the two variables silica and alumina
> with two other variables. Shouldn't be any harder.
Hi Taylor,
I think the standard Currie technique can be modified to be more
useful to a functional potter. It sounds like May has done it. As I
said in my earlier post I have encouraged Ian to address that and I
don't know if he has or not. But his "standard" technique--the one
published in his book-- gives as many as 33 of the 35 grid points
that are not of interest to me as they will be outside the silica,
alumina, or expansion limits of interest to me. But there is still a
tremendous area to explore that are within the limits of interest to
me. I just have to modify his technique substantially if I want to do
it with his 5 x 7 grid approach.
Regards,
John
John Post on thu 6 mar 08
I agree with John Britt about the how beneficial the grid is for
discovering new things.
If you go to my cone 6 website below and click on the nickel grid, you
will see just how sensitive nickel is to alumina and silica. It
changes from a bright purple when there is a small amount of alumina
to a blue when the alumina increases. By creating one grid I learned
more about nickel and its properties than I could have learned by
mixing a bunch of nickel glazes one at a time. As Ian says "It's like
fishing with a net instead of a hook and line."
John Post
Sterling Heights, Michigan
http://www.johnpost.us :: cone 6 glaze website ::
http://www.wemakeart.org :: elementary art website ::
On Mar 6, 2008, at 7:02 PM, John Britt wrote:
> Rather
> than assuming that you know, you are actually discovering new things
> that
> you did not know. It is really unlimited. Plus you are looking at
> each of
> the fluxes in relation to silica and alumina, as well as colorants,
> and
> these do not fit neatly into patterns.
John Sankey on thu 6 mar 08
"?John, am I wrong in thinking that a non-standard Currie grid would do
the trick? One simply replaces the two variables silica and alumina
with two other variables. Shouldn't be any harder."
Absolutely correct.
If you want to understand things, you have to ask what scientists call
productive questions, ones that have the maximal chance of increasing
understanding from your current level. Once you've done one silica-alumina
grid, you have a base feel for how silica and alumina work together, theres
no point in repeating the same thing ad nauseum. Repeating it with other
variables is definitely the way to go.
John Sankey
---------
Include 'Byrd' in the subject line of your reply to get through my spam
filter.
I can only read text mail, no attachments.
Ron Roy on thu 6 mar 08
This is excellent advice from John Post - use the information you get to
move in the direction you think would be an improvement.
RR
>To continue with your pantyhose analogy...
>
>While the size chart may not always tell you which size to purchase
>initially, the chart might be useful after you tried on a pair that
>didn't fit and then had to make another selection. The information
>you got from the first pair coupled with the chart might help you to
>make an informed decision about which size to try next.
>
>I think that the usefulness from a limit formula comes into play after
>you have tested a glaze and made a change or two to it. Then you can
>see in which direction the numbers are going and study the results you
>are getting. I prefer Ian Currie's grid method that shows you 35
>variations of alumina and silica over a single tile. Instead of
>adding clay or silica in small little increments to try and cure a
>glaze problem, I like to see what happens when alumina and silica go
>from as little as possible in the glaze until there is an overload.
>Then you can examine the grid tile and see what effect a progression
>of alumina or silica has on the glaze.
>
>I don't like to look at the limit formula for a glaze before I test
>it. I prefer to look at the numbers after as an explanation for what
>is going on. The more numbers you have to look at, the more
>information you have to draw inferences from. That's why Ian's grid
>method is so powerful. In a 2-3 hour session you can create a grid to
>serve as a "visual" starting point for understanding a glaze and the
>numbers attached to it.
>
>The map is not the territory.
>The limit formula is not the glaze.
>
>John Post
>Sterling Heights, Michigan
>http://www.johnpost.us :: cone 6 glaze website ::
>http://www.wemakeart.org :: elementary art website ::
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
John Britt on thu 6 mar 08
John,
I agree that you can substitute other materials for the silica and
alumina. If you have done the Currie Grid you will know that it is just a
series of line blends with clay going up and with silica going across. He
just uses moles of alumina and silica.
I do have to disagree with the statement you wrote: =93Once you've done one
silica-alumina grid, you have a base feel for how silica and alumina work
together, there=92s no point in repeating the same thing ad nausea.=94
Having done the exercises in his book I know that this is just not true.
When you run the grids you are constantly amazed at the outcomes. Rather
than assuming that you know, you are actually discovering new things that
you did not know. It is really unlimited. Plus you are looking at each of
the fluxes in relation to silica and alumina, as well as colorants, and
these do not fit neatly into patterns.
One thing that I found amazing is how the same percentage of iron oxide in
a base can result in a transparent amber glaze and an opaque temmoku. I
think it is the Iron Test #5, but I don=92t have my book here to check. It
is a triaxial type test. If you merely ran the iron tests in his book you
would learn tons!
So thinking you have the feel for alumina and silica and what it does is
no substitute for actually doing it and seeing.
The beauty of his workshop is that you can complete most of the book in
one weekend (depending on the number of participants), so you don=92t have
to do all the work yourself.
John Britt
John Britt on fri 7 mar 08
Ian,
Glad you joined in on this. It was getting a little lonely out here, just
me and John Post holding down the fort.
As you said: "Probably one of the more difficult things to get across to
students is that "understanding" is just as important, perhaps more so,
than discovering nice glazes." And I will add =93stable glazes=94.
It is a bit curious to me anyone would try to limit education and
discussion to "stable" glazes. This is only one small aspect in a vast
universe of amazing glaze adventures.
I encourage everyone to take Ian=92s workshop.
John Britt
www.johnbrittpottery.com
Ian Currie on fri 7 mar 08
On 07/03/2008, at 3:00 PM, Automatic digest processor wrote:
> Date: Thu, 6 Mar 2008 08:46:34 -0500
> From: John Sankey
> Subject: Re: The limits of limit formulas, part II
>
> "?John, am I wrong in thinking that a non-standard Currie grid
> would do
> the trick? One simply replaces the two variables silica and alumina
> with two other variables. Shouldn't be any harder."
>
> Absolutely correct.
>
> If you want to understand things, you have to ask what scientists call
> productive questions, ones that have the maximal chance of increasing
> understanding from your current level. Once you've done one silica-
> alumina
> grid, you have a base feel for how silica and alumina work
> together, theres
> no point in repeating the same thing ad nauseum. Repeating it with
> other
> variables is definitely the way to go.
>
> John Sankey
Hi John
Just thought I should try to clear this up... I will be putting up a
new website soon with lots of images of grid tiles that will show
quite categorically that there is much point in doing a new grid if
you wish to understand a new set of fluxes, or the way colourants or
opacifiers work with that set of fluxes.
What you are suggesting can be the next step in zeroing in on
understanding a particular glaze. Once I've found something
interesting on a grid, I will take that glaze and do a line blend or
a 2-variable rectangular blend (bi-axial) (avoid quadraxials if you
want to understand what is going on... they look the same but are a
conceptual mess... yes I know they have been used for yonks, but this
has always been the case), or a triaxial to explore that glaze further.
The so-called Currie grid is a simple experiment varying alumina and
silica with a chosen set of fluxes (your choice). It is one of the
most powerful and revealing glaze experiments you can do, and people
have been doing it for over a century. My main contribution has been
to standardize the method to make it quick and easy to do and to get
all the recipes.
Part of the standardization involves using kaolin as the source of
alumina, and quartz as the source of silica.
What I call a non-standard grid is still varying alumina and silica,
but changing from the use of kaolin and/or quartz. For example you
could use ball clay instead of kaolin. I might do this if my focus is
once-fired glazes... ball clay is often more appropriate than kaolin
in once-fired glazes.
So moving towards what I think you are suggesting, John, is where we
have learned something from a grid we have done, and want to zero in
on something specific, or try different colouring oxides, or other
additives like rutile etc.
[ Note: I always recommend if you introduce additives (colourants,
opacifiers etc.) into the grid, all 35 glazes should have the same
amount, otherwise you can't tell what is causing what changes, and
like in the quadraxial example you have a conceptual mess. You can't
have more than 2 independent variables on a flat experiment without
running into this problem. (Triaxial is 3 INTER-dependent variables,
and that works fine.)]
But after doing a grid, the next stage is: choose just one glaze
from the grid, and do the sort of experiment most of us already
understand, like a line blend, bi-axial blend, triaxial. You can
find the layout of these types of experiments in most books on
glazes. This is where your "productive questions" come in (what
additives, what combinations, what amounts, what firing, what clay
body) ..... and it is an interesting and creative stage in the whole
process that brings art and science together, where they belong!
They are two sides of the same creative coin. :)
Probably one of the more difficult things to get across to students
is that "understanding" is just as important, perhaps more so, than
discovering nice glazes. In my experiments, whether they are a grid,
line blend or whatever, I always try to lay the experiment out so the
chosen variables are separated out. Then cause and effect is
obvious. Increasing alumina in this case causes this... increasing
iron in this case causes this. To understand what I'm saying,
imagine applying the 35 glazes from one of my grids not to a grid
tile (35 on one tile) but one glaze per separate tile. Then imagine
mixing them all up so they are in random order. Now all you can see
is "this glaze is nice... this one is boring.... this one is
crazed... etc. Now put the glazes back in the correct order, with
alumina increasing from bottom to top of the grid, and silica
increasing from left to right. Patterns become obvious and cause and
effect jump out. You understand, and from understanding you can
begin to predict and plan and engage your intellect in your
exploration of the (ceramic) universe.
I can probably summarize this way: Use one of my grids to find the
general area (general proportions of alumina and silica) you want to
work with. This will be a major determinant of glaze surface, glaze
fit, stiffness, durability, opacity, and lots of other local features
like stringing, opalescence, crystals etc. Choose a glaze from your
chosen area on the grid to fine tune with line blends, triaxials,
trials with clay and firing etc. This gives you a standard reference
framework to in time build up a deep understanding of the science...
and even if you wish eventually work very intuitively with glazes,
this will give you the foundation on which you can do this.
Apologies for my long silence... I am not able to always tune in. If
you want to be sure I read your post, please Cc me. I will post soon
on my upcoming workshop tour of North America and Europe, and also
regarding my new website (different address) that will have many
images of grid tiles that show the difference between understanding
and "ad nauseam". :)
Regards
Ian
Ian Currie
http://ian.currie.to/ (This is the old website, still working....
will notify the new address soon.)
Ron Roy on sat 8 mar 08
May is exactly right - the combination of calculation and line blending
together is a magical combination which leads to a much better
understanding.
Any type of line blending is useful to see what happens when the oxides are
changed - knowing how much they have changed leads to further ideas to get
the kind of glazes you want.
It applies to all simple line blends, triaxials and grids.
=46or instance - if you know what the calculated expansion is - that you nee=
d
to prevent crazing and shivering on the clays you use - then you can use
mixtures at each end of a line blend with ideal expansions. Then every
glaze in the blend will fit your clay.
Same with stability - start with stable glazes and you end up with stable
glazes.
Line blends can be used in a creative way - the only limit is your mind.
Doing them without calculation is limiting yourself - you see so much more
when you see the oxides changing and are looking at the results.
Understanding the function of oxides in a glaze is basic - the more you
understand the better potter you will be.
RR
>John H; Glazemaster and Currie Grid together is a beauty. I use them
>together often. Because I think through my flux set before testing, I
>always get green squares from my Currie Grids. Nevertheless, it would be
>interesting to pull out some =92=C4=F2unstable=92=C4=F4 glaze from the grid=
and test
>them according to MC6G and perhaps, more interesting glazes can be added
>to the stable pool.
>
>Best Regards
>May
>Kings County, NY
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Alisa Clausen on sun 9 mar 08
On Fri, 7 Mar 2008 20:14:44 -0500, John Britt wrote:
>Ian,
>
>Glad you joined in on this. It was getting a little lonely out here, just
>me and John Post holding down the fort.
>
Hi John
You should not be lonely! March 2008, week 1 quotes several opinions in
strong favor of the usefulness of Ian's grid.
I was especially in agreement with those who support the grid combined
with other methods to give a broad and practicle underdstanding of glazes.
Of course, it was fantastic, as Clayart can be, to get information from
the source, and Ian did that for us.
Best regards from Alisa in Denmark
Hi John H.
Ian's grid is an excellent way to understand how materials influence a
glaze mixture. It is has personally taught me to look at the 35 different
glazes, notice the differences and then refer to the simple way he has set
up understanding the influence of Silica, Alumina and a range of fluxes.
Short said, Grids are flash cards for understanding materials.
They are invaluable for learning what materials do.
Normally we fire a set of 3 grids to see what glazes look like on
different clays, so in one go, we have 105 examples. Not wasted time for
any potter who wants to make glazes and understand what they are looking
at.
You are not finding the grid useful maybe because you are informed enough,
to say the least, to cut right to the chase for the glazes you want.
However, the majority of the potting community are building up their glaze
knowledge and the Curry grid is an excellent exercise to learn from,
whether or not they are aiming for table ware or sculpture surfaces. I
also have learned about which materials "bully" another by simple 50/50%
Gartside experiments. By keeping 50% of one material, say Ball Clay, and
adding 50% of everthing else I have in the studio, I could get a broad
range of which materials sjpw more "muscle" in spefic combinations. Not
scientific, but I could take it further and understand it scientifically,
but first learning what materials look like in the melt and later find out
why.
I would not recommend that anyone only learn one method with one aim,
because there is a lot of discovering lost by following one school of
thought.
MC6G has undoubtedly opened an important venue for understanding stable
glazes according to your parameters. It does not at all lessen that
importance by working side by side others who have a different approach to
understanding glazes, or different goals.
Both Ian's grid and MC6G are independently great sources of information
and learning. If a potter understands most of the information offered
from both, I would say they have a huge foundation to build on. A few
Gartside experiments, and one can learn and learn.
.
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