Martin Kastner on mon 9 jan 06
I am a designer working on tableware prototypes. One of those people
despised by most potters.
I moved to a different city (from San Deigo to Chicago) and lost my previous
contact for firing porcelain in reduction.
I have enough experience with moldmaking and slipcasting to produce the
pieces. I have an electric kiln and have fired prototypes myself to test the
form. But I need to fire some items that would actually have the bright
whiteness of lightly reduced porcelain. None of the 'white' porcelain slips
quite get there by straight-forward firing in the electric kiln. Is there a
way to achieve this in an enclosed saggar with pure graphite or other oxygen
depleting agent? Or by some other means?
I would appreciate any advice with this.
Thanks,
Martin Kastner
W J Seidl on tue 10 jan 06
Martin:
Take this for what little it is worth, but:
With the porcelain I use (Miami Clay, admittedly a throwing porcelain) I
have no problems getting a reasonably bright white in oxidation.
I fire in an electric to ^10, no saggars, no kiln vent (my kiln is in a
covered outside space).
You might want to try a different formula porcelain. You should be able =
to
achieve your need for production through slipcasting, while maintaining
whiteness in oxidation. Southern Ice, for one, is a brilliant white. =
It
might be a good base for a new formula.
And of course, your post begs the question as to why you think you would =
be
despised by most potters? We don't all throw, or mold, or hand-build, or
slipcast, make beads, etc. Surely there is room at the table for us all
.
Best,
Wayne Seidl
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Martin =
Kastner
Sent: Monday, January 09, 2006 6:03 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: porcelain in oxidation
I am a designer working on tableware prototypes. One of those people
despised by most potters.
I moved to a different city (from San Deigo to Chicago) and lost my =
previous
contact for firing porcelain in reduction.
I have enough experience with moldmaking and slipcasting to produce the
pieces. I have an electric kiln and have fired prototypes myself to test =
the
form. But I need to fire some items that would actually have the bright
whiteness of lightly reduced porcelain. None of the 'white' porcelain =
slips
quite get there by straight-forward firing in the electric kiln. Is =
there a
way to achieve this in an enclosed saggar with pure graphite or other =
oxygen
depleting agent? Or by some other means?
I would appreciate any advice with this.
Thanks,
Martin Kastner
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Bruce Lucas on tue 10 jan 06
Martin Kastner wrote:
>But I need to fire some items that would actually have the bright
>whiteness of lightly reduced porcelain. None of the 'white' porcelain slips
>quite get there by straight-forward firing in the electric kiln.
>
Laguna's "Frost" is a very white (in oxidation) translucent cone 6
porcelain, available in moist form. Would it be possible to make it
into a casting slip?
Actually this is as much a question to the group as a suggestion - is
this even a workable idea? I'm actually experimenting with that now,
have successfully made a slip at a specific gravity of about 1.76 that
seems to have about the right consistency by adding Darvan 811 and water
and mixing in a blender. (I don't have any results with casting it yet,
and in any case I'm such a beginner that I doubt my results would be
particularly meaningful to you...)
Cheers,
Bruce Lucas
Martin Kastner on wed 11 jan 06
Thanks for the suggestions.
I actually have tried the Frost White slip by Laguna. But it doesn't quite
get to the point where I need it color-wise.
It is blue-grayish with a hint of the typical oxidation creaminess. In other
words off-white. It is okay on its own but once on white linen the
off-whiteness really shows. Our clients are accustomed to seing the
mass-produced whiteware by Bernadaud, Montagtina and the likes. The
whiteness of the prototypes needs to be comparable. The reduction fired ware
was within the color range (slip made from English porcelain from Laguna is
what we used in California).
Our Southern Ice tests in oxidation had the same creaminess issue as other
tested claybodies.
As far as being disliked by potters, it has been my experience in a few
cases where what we need for our purposes (control, predictability,
consistency) is seen as a heresy, I was told by one potter to go buy some
plates at Crate & Barrel, that they have plenty of white tableware there.
Martin Kastner
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