Lee Love on sat 30 jan 10
On Sat, Jan 30, 2010 at 4:14 PM, Bill Merrill wrote:
> changed. Not only did the body expand a great deal, but it was left very
> porous. It was like high-fire bisque ware.
Thanks for this info Bill. Japanese shino clay (yes, shino is put on
a specific clay and its attritbutes are an important aspect of shino)
also seems like bisque, not fully vitrifying at cone 13. You could
touch your tongue to it and feel absorbtion, like bisque. It is
called Mogusa, the same as moxibustion incense.
The tea masters liked the softness of mogusa clay. It was
similar to raku and made a soft sound when the bamboo whisk is used in
it.
It really does a disservice to the range of clay experience
there is available to us, when people demand that all pottery work be
wash & ware and dryer safe. Folks with an aesthetic that demands
that all ceramics follow kholar toilet bowl qualities really have
blinders on.
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97tha=
t is, "T=3D
he
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Bill Merrill on sat 30 jan 10
Could be associated with IED's....Tee Hee...many of these can and will
explode...Be cautious. Materials have changed since this was written
over 30 years ago. Glazes fitting on a flame ware body is another
challenge....I must admit it was fun working with flame ware for, in my
case experimental clay reasons.
=3D20
=3D20
Flameware Coming in two parts
=3D20
=3D20
by Ron Propst
=3D20
=3D20
This article first appeared in Studio Potter, Volume 2, Number 2 (Winter
1973/74).
(Note that company addresses and phone numbers may have changed since
that time.) Copyright (c) 1974 by Studio Potter. All rights reserved.
May be reproduced with permission of Studio Potter.=3D20
=3D20
My interest in flameware first began when the stoneware body I was then
using showed a disappointing inability to remain ovenproof. No matter
how I changed the formula, casseroles continued to break. This caused
great grief to me, and to my customers too. I became determined to
produce a type of pottery which would adapt to temperature changes
gracefully.=3D20
=3D20
Today my feelings remain the same. Considering the amount of technology
presently available, studio potters should be able to produce a ware
sufficiently stable to be capable of standing up under severe conditions
of direct-flame thermal shock.=3D20
=3D20
My first experiments in flameware were involved with the use of
petalite. My work with this body was very brief, due to the Rhodesian
embargo which halted shipments of petalite. The following are some
comments on my general findings on the use of petalite in flameware
bodies.=3D20
=3D20
Most flameware bodies consisting of approximately half clay and half
petalite work well. A higher percentage of fire clay and less of ball
clay seems to be the most durable. If a flux is needed to seal the clay
body, talc seems to be the best. I cannot include a list of such
workable formulae, due on my part to lack of testing and general use of
petalite bodies. There is, however, a little-known current American
supplier of petalite, who will, I understand, also send samples for
testing:=3D20
=3D20
Charles B. Chrystal Co., Inc.
53 Park Place
New York, NY 10007=3D20
=3D20
As soon as petalite became generally unavailable, I began work with a
local mineral called spodumene. Spodumene is quite different from
petalite. It is higher in lithium and iron oxide and lower in silica.
Moreover, it has a strange talent: at 1700F, the crystalline form of
spodumene expands instead of shrinking.=3D20
=3D20
In my first test with spodumene this trait became evident. The early
tests involved using 50% spodumene and 50% clay. The clay body expanded
about two inches and sealed the ware to the kiln shelf above. While
chipping at the kiln shelves, I decided that something needed to be
changed. Not only did the body expand a great deal, but it was left very
porous. It was like high-fire bisque ware.=3D20
=3D20
The next series of tests was involved with using pyrophyllite and
spodumene. Pyrophyllite is a low-grade mineral (an aluminum silicate)
mined in North Carolina. It is used primarily in wall tile bodies where
it deceases thermal expansion. I felt that the clay body needed an
increase in alumina content, and pyrophyllite would give the increase
needed. This helped a great deal with the expansion problem, but the
body was still quite porous.=3D20
=3D20
Since that time I have revised the body at least twenty times. The
following formula is the clay body I have used for the past five years.
It is successful with different types of ball clay and fire clay. I am
not sure how the body would measure up on a dilatometer (a machine which
measures thermal expansion), but it has been successful for me and a
number of other potters around the country. Pottery made of this body
has successfully been used on top of gas and electric stoves.=3D20
=3D20
Ron Propst's Flameware Formula=3D20
=3D20
Spodumene (200 mesh)
=3D20
30
=3D20
Pyrophyllite (200 mesh)
=3D20
10
=3D20
Feldspar (200 mesh)
=3D20
10
=3D20
Ball clay (OM#4)
=3D20
20
=3D20
A.P. Green Fireclay
=3D20
30
=3D20
Western Bentonite
=3D20
2
=3D20
Macaloid
=3D20
1
=3D20
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