Antoinette Badenhorst on mon 12 apr 10
Thanks again=3D20
to those that helped me with this event. There were requests for a report, =
=3D
so here goes. Anyone that attended, please fill me in where I leave things =
=3D
out.=3D20
We had the following on the agenda, but got half way through. I report on t=
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hese in quotes.=3D20
=3DC2=3DA0=3D20
WHAT IS CONSI DER ED AS TRUE PORCELAIN?=3D20
Can we assume that the material discovered by Marco Polo in ancient China a=
=3D
nd the material we're using today are essentially the same or is it defined=
=3D
according to its final appearance?=3D20
=3DC2=3DA0=3D20
=3DE2=3D80=3D9CAll the traditional characteristics were mentioned, but when=
the q=3D
uestion about colored porcelain came up, it came back to "porcelain is porc=
=3D
elain by its ingredients and the make up there of. Jon Singer and Jon Pachi=
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ni had some interesting and very valid remarks about the technical qualitie=
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s of a porcelain body. I would love for them to respond on this point again=
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"=3D20
SEMI PORCELAINS; WHAT DEFINE THEM?=3D20
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"We did not get to answer this one; we got too far carried away with the pr=
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evious question. I do think this is a very valid question to ask though, si=
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nce I think there are often times confusion about that"=3D20
TECHNICAL CHALLENGES.=3D20
=3DC2=3DA0=3D20
Cracks during:=3D20
"We discussed the following kind of cracks"=3D20
-Making: challenges of joints.=3D20
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"I am particularly challenged with joints with the Southern Ice. There are =
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always a slight discoloration and a little raised line where I join.(not ex=
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actly a crack) I was advised to overlap (there was a technical word for =
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that)=3DC2=3DA0the joints. It stays a challenge and one needs to keep the w=
ork =3D
wet under plastic, or as I do, I use plastic food containers upside down. P=
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aper in the clay has its advantages and disadvantages, but key is to use th=
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e Paperclay fresh before the fibers start breaking down. Vinegar=3DC2=3DA0i=
n cl=3D
ay water helps some to deflocculates the clay, others use miracle water (se=
=3D
e the recipe elsewhere on clayart)"=3D20
=3DC2=3DA0=3D20
-Bisque:=3D20
=3DC2=3DA0=3D20
"Paperclay is considered as a good mender for cracks; (Other additions to t=
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he paper clay =3DC2=3DA0 are also somewhere in the archives) wet the pot, o=
pen =3D
the crack to eliminate the clay memory and start filling it up with fresh p=
=3D
aper clay. The use of grinded bisque in the cracks was also discussed as a =
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good option to fill cracks up, particularly since it is already shrunk.=3D2=
0
=3DC2=3DA0=3D20
The old problem of s-cracks came up again. Porcelain clay needs to be wedge=
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d before use. Spread the moist evenly, get the clay particles in line, is w=
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hat it is all about. Cone centering also came up as an important act. Someo=
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ne mentioned a method used in which the clay get cone centered, cut loose a=
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nd turned over so that the top becomes the bottom and cone centered again. =
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If one can get away with other clay bodies without wedging...........who sa=
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id porcelain is a diva!=3DC2=3DA0=3D20
=3DC2=3DA0=3D20
"The old matter of trimming also came up, when someone showed us her precio=
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us little bowl with a s-crack on the bottom. The piece were beautifully thr=
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own, but the trimming was half completed, so we advised her that she should=
=3D
take a toothpick or a thumb tack, measure the thickness of the rim=3DC2=3D=
A0an=3D
d push it through the piece on the bottom side above the foot rim, just the=
=3D
measured thickness. Trim it until you hit the pin and you will not go thro=
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ugh the wall, but trim it evenly. Once again, one can get away with these u=
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neven thicknesses with other clay bodies, but porcelain is an animal! Compr=
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essing, compressing, compressing!=3D20
=3DC2=3DA0=3D20
Thank you Lynn Goodman for explaining your perfectly trimmed bowls; maybe y=
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ou want to explain it to us again."=3D20
=3DC2=3DA0=3D20
-SUPPORT DURING FIRING=3D20
=3DE2=3D80=3D9CThe clay moves in the firing and is always a huge challenge =
for po=3D
tters. Clay will sometimes just slump, but often times literally tear to pi=
=3D
eces and even topple over. =3DC2=3DA0A safe angle for design is 45 degrees =
with=3D
out long flat areas that hang unsupported in the air. I use heaps of silica=
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,=3DC2=3DA0to support unglazed surfaces and often nest the pieces into sili=
ca (=3D
beware of the danger when using it.....act responsibly), other potters use =
=3D
aluminum silicate. Any=3DC2=3DA0fire resistant object (including kiln posts=
) th=3D
at will survive a porcelain firing temperature can be used to support the o=
=3D
bjects. Somebody mentioned kaowool that will be less messy. Is there a diff=
=3D
erent kind of silica product? I think somebody mentioned some kind of a bla=
=3D
nket. If someone knows about that, please fill us in."=3D20
=3DC2=3DA0=3D20
GLAZES=3D20
"We were just touching the glaze subject. It seems that many get away with =
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glaze dipping their work. The method that one chooses has all to do with th=
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e glaze fit, thickness of glazes and the thickness of the porcelain object.=
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We discussed the average shrinkage of porcelain, necessary for controlled =
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cool down, but we did not have enough time to go in-depth into this subject=
=3D
.=3D20
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=3DC2=3DA0 Pinhole problems came up and there were different opinions about=
the=3D
temperature of bisque firing to obtain "smooth glazes"=3DC2=3DA0 Jon Pachi=
ni s=3D
uggested that porcelain should be bisque fired to ^04. The thickness of gla=
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zes is often obtained by the absorbing ability of the bisque. Most of the p=
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otters there were doing electric firing; one ash glaze. It would be nice to=
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hear from others that fire differently."=3D20
Tips.=3D20
=3DC2=3DA0=3D20
"Bryan Johnston explained how he ball mills some of his colorants to elimin=
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ate speckles in the clay. His mugs were beautiful and smooth with a very go=
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od glaze fit."=3D20
ARE CRACKS ALLOWABLE IN THE FINAL PRODUCT OR NOT?=3D20
Curtis Benzle approach and philosophy.=3D20
=3DC2=3DA0=3D20
=3DE2=3D80=3D9CI wish we had a chance to discuss this subject. Fortunately =
Curt s=3D
end out the article that he wrote about this some years ago and I trust tha=
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t everybody on my list got that. This is maybe something that one has to ma=
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ke out for one self. Cracks in the right places might be attractive and in =
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others a distraction."=3D20
THE REST OF IT=3D20
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"We could not talk about any of the rest that was lined up for discussion (=
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see below). Hopefully we will discuss that next time.=3D20
=3DC2=3DA0=3D20
There were a few suggestions of how we should organize the next meeting. Le=
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t=3DE2=3D80=3D99s see what the future holds.=3D20
=3DC2=3DA0=3D20
In the meantime if anyone wants to add comments (I am sure I did not mentio=
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n all that was said), please do so or if you have a new subject to add to t=
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he list, please feel free and make sure I get that."=3D20
Suitable for food safety. Other options?=3D20
Different glazing =3DC2=3DA0methods.=3D20
Thin porcelain/ thick. =3DC2=3DA0=3D20
Firing:=3D20
Different firing =3DC2=3DA0methods. =3DC2=3DA0=3D20
Support: what is available?=3D20
=3DC2=3DA0=3D20
Manipulate =3DC2=3DA0movement; to what extend before cracks may appear. =3D=
C2=3DA0=3D
=3D20
Cool down cycle?=3D20
=3DC2=3DA0=3D20
Tips.=3D20
Design.=3D20
Approaches during making. How does design of a piece affect successful firi=
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ng?=3D20
Wheel throwing tips and techniques.=3D20
How does design changes the "face" of porcelain from the first discovery to=
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the 21st century?=3D20
Alternative firing methods.=3D20
Paper porcelain.=3D20
Colored porcelain.=3D20
Thanks again to everyone that contributed to this successful first porcelai=
=3D
n chat. Please make sure that I get your comments, good or bad and if you c=
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ould not attend this time...........see you next time.=3D20
Best wishes.=3D20
Antoinette Badenhorst=3D20
Lincolnshire, Illinois=3D20
www.porcelainbyAntoinette.com=3D20
marci and rex on mon 12 apr 10
At 12:30 PM 4/12/2010, Antoinette Badenhorst wrote:
> I think somebody mentioned some kind of a blanket. If someone
> knows about that, please fill us in."
> and .
>"Most of the potters there were doing electric firing; one ash
>glaze. It would be nice to hear from others that fire differently."
I regret that I missed most of the porcelain discussion . It was
unfortunately scheduled at the same time
as Arnold's excellent presentation about kilns and since I have
the same ignorant reverence and confusion about kilns
that the early cavemen had about fire, I decided to do
Arnold's presentation . I wasnt disappointed. It was terrific... (
Thanks, Arnold ...and btw, thanks for all the fabulous videos on
the Paragon site... )
So, anyway, by the time I wandered over to the porcelain
group, it was just about finished... CRAP !!!
I hope to be part of things next year.....
...Anyway :
There is something called fiber blanket that you can buy in a
roll from places that sell fireplaces and wood stoves...
The stuff I have is about 2 inches thick and feels sorta like
mutant cotton batting from the Planet Krypton ... I dont know
the exact rating of it but it will hold through a cone 6... dont
know about a 10 ...
and then there is Prop It which also resembles cotton batting
but not as mutant.... which may be the same thing as kaowool...
and it will hold through a cone 6...maybe hotter ...
As for firing... I fire differently. ( Would you expect
anything else from me ? LOL ) .... I do my pendants and
plaques once-fired... with either thinned underglaze over
the dry clay ( Laguna Frost ) for color if Im doing some of
my organic pendants and then clear glazed with a commercial clear
glaze ( Amaco clear) ... or , if Im going to eventually
chinapaint the piece, just clear glaze over
the dry clay and then fired once to cone 6 ...
Marci the chinapainter
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