Steve Slatin on thu 17 jun 04
Tod --
I know less about glaze formulation than most of the people on this list --
but I think the suggestions so far have not taken into account your target
for glaze scientists.
Using Currie grids is great if you have gobs of time, excellent scales,
good experimental technique, etc. Most people do their glaze
experimentation somewhat less rigorously. I'd think a simpler
approach for elementary ed would be better.
I don't know what materials you have, cone you fire to, etc. This governs
much of the detail of how you do your work. What I'd think would be a
great experiment for the kids, though, would be to take a single glaze
'recipe' of the simplest characteristics possible, and tinker from there,
using underglazes, overglazes, adding oxides, etc. That's plenty enough
variety for lots of adult potters.
You say you will be firing 'low to mid temperature.' This means
different things to different people. Let me suggest something like
this as a starting point, which will ONLY work if you are firing to
about cone 6.
Start with Clear Ian Begg, from the
http://www.utpb.edu/courses/arts4365/formulae/glaze/functional.htm
website. It is mixed with frit 3134 50% by weight, 30% EPK, 20%
silica. All three items have well-known constituents and the glaze
is tolerant -- can be overfired or underfired or put on thin or moderately
thick and it's still a clear, shiny, not-too-runny glaze. You can also be
a fair bit off on the weights and still get some kind of result.
If you can do it with multiple firings, first do a firing with small
variations -- 45% 3134, 35% EPK (and regular silica) could be one,
25% Silica, 30% EPK, 45% 3134 could be another, etc.
The kids will be able to see the differences in result with more
silica, more flux, more alumina.
(It's easy to work with these three ingredients because 3134
has no alumina, and is roughly 1/2 flux, 1/2 silica, and EPK
is about half silica and half alumina, with almost no flux.)
You can take a variety of slips, oxides, etc. and paint them in
narrow rings on a bowl or cylinder, then dip the ware in this glaze.
Bingo, instant comparison of a half-dozen underglazes. With
a second item, you dip first, and then do overglazes. That
gives you two good experiments and maybe a total of a dozen
items to compare on just two pieces with a single batch of
glaze.
Being a very simple recipe, you can make up small quantities
of Ian Begg for testing. Make a dozen of them, and let the
kids experiment with 1/2 percent of one oxide and make up the
same kind of under and overglaze test ware. Then a 1/2
percent with a second colorant, then a third, etc.
When done, come back for 1 percent, then two, then three.
If a kid with good handwriting takes careful note of what's going
on, when you're done you'll have some great examples of
how glazes react with underglaze, overglaze, and colorants
mixed in.
Good luck.
Tod Spedding wrote:
I am interested in beginning a series of low-fire glaze experiments this
summer with my elementary school students and am looking for
pointers/referrals/suggestions.
I'd like to begin working with the most basic of glaze ingredients (as, a
source of silica + flux + binder), with the intent of gradually adding
ingredients, building an understanding of materials/formulae.
-- Steve Slatin -- Entry-level potter, journeyman loafer, master obfuscator
No website, no sales room, no scheduled hours
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Tod Spedding on thu 17 jun 04
I am interested in beginning a series of low-fire glaze experiments this
summer with my elementary school students and am looking for
pointers/referrals/suggestions.
I'd like to begin working with the most basic of glaze ingredients (as, a
source of silica + flux + binder), with the intent of gradually adding
ingredients, building an understanding of materials/formulae. I see
systematically varying the proportion of ingredients, perhaps applying a
series to the surface of a cylinder, for easy comparison.
Am looking for ideas re basic materials, a starting place, or a source for
ideas. What must we explore? Perhaps there is a historical connection.
We are confined to low/medium temperature.
Thanks hugely in advance.
Tod Spedding
The International School of Monterey
Bruce Girrell on thu 17 jun 04
> I'd like to begin working with the most basic of glaze ingredients (as, a
> source of silica + flux + binder), with the intent of gradually adding
> ingredients, building an understanding of materials/formulae. I see
> systematically varying the proportion of ingredients, perhaps applying a
> series to the surface of a cylinder, for easy comparison.
I suggest that you look at Ian Currie's approach (see
http://ian.currie.to/original/index.html). It is a very systematic approach
to the study of glazes. Although Currie places his emphasis on higher firing
glazes, all that is different for you is the fluxes (corner C), which cause
the glaze to melt at a lower temperature.
Currie's grid approach makes a great team project. You can have someone
checking the ingredient list, someone fetching ingredients, someone
weighing, someone mixing, someone taking notes, and someone applying the
glazes. Then if you add another variable, a different colorant, a different
clay body, or maybe even a different flux, you can set up another entire
team. Keeping 30 people busy would not be a problem at all.
The resulting tiles are very instructive. You can see a eutectic trough -
what combinations of silica, alumina, and fluxes yield the lowest melting
point. You can see how the silica/alumina ratio affects the surface
properties and glaze fit. If you wanted to you could do an acid test to see
the effect of the silica/alumina on glaze stability. Chances are you will
also discover an absolutely lovely glaze in one of the combinations that you
would have never otherwise tried.
Currie's method is recipe based which should be more appealing for young
students. However, an obvious extension to Currie's method would be to
incorporate a glaze calculation program to analyze the glazes on a molecular
basis if you have any students that are advanced enough to understand what
is going on (or maybe that would be a part that you do). Then you would
begin to get a physical feel for what all those funny numbers in a unity
formula mean.
Have fun!
Bruce Girrell
in very rainy northern Michigan where all the vegetation is loving the rain.
Looks like a jungle out there.
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