clifton wood on thu 22 may 03
hi, John.
thanks for the posting & all the work.
question: what happens to the cone 6 glaze stability when fired in reduction? is
there a short answer?
background:
i take classes at a local college.
last year, we moved from cone 10 reduction firings for elective classes to cone 6
reduction.
the glaze pallette we're using isn't optimum... not a great color selection,
everything is opaque except clear, fit problems on clay body, not robust under
varying firing conditions, unforgiving to common glaze application boo boos, and on &
on & on.
i hope to spend the summer testing glazes to get a better pallette.
but most of the recipes i see are for ^6 oxidation, thus my question.
i know it's kind of scary having someone as uneducated as i do this work, but i'm
accurate & have lots of time / enthusiasm.
and i do plan to do the vinegar / change of color test for any finalists. i know
it's not enough, but it's a start.
also... if anyone out there has a ^6 reduction glaze that they adore, please send it
on.
in return, i can let you have the pallette we developed for ^10 R. many recipes
compliments of clayart members. it was swell, though i can't vouch for stability.
sorry.
thanks in advance.
sabra wood
John Hesselberth on thu 22 may 03
Hi Sabra,
I have no data on the cone 6 glazes fired in reduction so this will be
my considered opinion based on a tiny bit of data I have seen at cone
10. I really expect no measurable change. The amount of chemistry that
goes one within the glaze during reduction is really quite small.
Reduction before the glaze seals over can be significant but once it
seals over not much happens except right at the surface. You are
probably having no measurable effect on the base composition of the
glaze--you're primarily changing some of the colorant oxides to their
metallic form. It would be an interesting experiment to take a glaze
that leached in some measurable way when fired in oxidation--then fire
an identical sample in heavy reduction and measure it. I'll have the
leach testing done if you will make the samples. Careful attention
would need to be paid to firing them both to the same cone. Let me
know if you are interested in collaborating on this.
Regards,
John
PS Several people are using the glazes in Mastering Cone 6 Glazes in
reduction and having good success. The only one that is unsuitable for
sure would be the zinc base. I think I remember Marcia Selsor is off
to Italy now, but she has been firing C6 reduction for many years and
has shared her glazes before also.
On Thursday, May 22, 2003, at 01:04 PM, clifton wood wrote:
> hi, John.
>
> thanks for the posting & all the work.
>
> question: what happens to the cone 6 glaze stability when fired in
> reduction? is
> there a short answer?
>
> background:
>
> i take classes at a local college.
>
> last year, we moved from cone 10 reduction firings for elective
> classes to cone 6
> reduction.
>
> the glaze pallette we're using isn't optimum... not a great color
> selection,
> everything is opaque except clear, fit problems on clay body, not
> robust under
> varying firing conditions, unforgiving to common glaze application boo
> boos, and on &
> on & on.
>
> i hope to spend the summer testing glazes to get a better pallette.
>
> but most of the recipes i see are for ^6 oxidation, thus my question.
>
> i know it's kind of scary having someone as uneducated as i do this
> work, but i'm
> accurate & have lots of time / enthusiasm.
>
> and i do plan to do the vinegar / change of color test for any
> finalists. i know
> it's not enough, but it's a start.
>
>
>
> also... if anyone out there has a ^6 reduction glaze that they adore,
> please send it
> on.
>
>
> in return, i can let you have the pallette we developed for ^10 R.
> many recipes
> compliments of clayart members. it was swell, though i can't vouch
> for stability.
> sorry.
>
http://www.frogpondpottery.com
http://www.masteringglazes.com
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