Michelle Rhodes on sat 20 feb 10
What conditions favor the classic bluish chun look? My chun glaze
sometimes does not develop the bluish opalescence, sometimes does.
And how to control the size of the little bubbles? It's not nice when
they're too big. I'm firing both stoneware and porcelain, gas, ^9-10
reduction. Any books or articles you can recommend? I'm getting the
chun effect from Redart, Cornwall Stone, and a little wood ash. I'm
bisquing quite low, usually ^08, which may contribute to the big
bubble problem?
Thanks
---Michelle Rhodes Gardiner NY
Lee Love on sat 20 feb 10
On Sat, Feb 20, 2010 at 12:07 AM, Michelle Rhodes wrote:
> What conditions favor the classic bluish chun look?
Phosphorous is required for a true chun. The fine bubbles in the
glaze create the Rayleigh scattering effect, the same reason the sky
is blue. When you do a search on clayart, my recipe below shows up
(with a bunch of others.) To get a bright sky blue, you want to put
it on porcelain or another white claybody:
This is my Chun blue. I call it Paul's Chun because Paul Morse from
the UofMN gave it to me:
Custer 80
Whiting 7
FLint 7
WoodAsh 4
boneAsh 2
Y. Ocher 1
Bentonite 1
For purple splash: 3% copper slip on raw body. Sky blue on
porcelain or white stoneware.
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Craig Martell on sun 21 feb 10
Michelle was asking?
>What conditions favor the classic bluish chun look? My chun glaze
>sometimes does not develop the bluish opalescence, sometimes does.
>And how to control the size of the little bubbles?
Hello Michelle and other Chun (Jun) Enthusiasts:
The Chuns are produced by refraction of blue light waves. Lee aleady
mentioned this. Since you have a Chun that works I won't go into the
micron size of the necessary particles needed to reflect blue light
waves. Basically, they are a semi-opaque, opalescent glaze. Too
much, or too little opacity and the blue is in the toilet.
Chuns need to be applied thickly. The light refraction will not take
place if the glaze is applied to thin. This also causes the glaze
to pick up alumina from the claybody and that will put the kibosh on Chun B=
lue.
These glazes also benefit from a slower cooling. They will become
bluer and more crystalline depending on the composition of the
glaze. Also, if overfired they will most likely be too transparent
to form the blue. Again, depends on the glaze makeup too.
I would suggest bisque firing to cone 06 to rid the clay of organic
carbon burnout. As Ivor mentioned, Cornish Stone gives off fluorine
gas. If your glaze is too viscous the gas cannot fully pass out of
the glaze.
regards, Craig Martell Hopewell, Oregon
ivor & olive lewis on sun 21 feb 10
Dear Michelle Rhodes,
Two books by well respected authors that you may wish to seek in your local
Library.
Robert Tichane, "Celadon Blues. Recreate Ancient Chinese Celadon Glazes"
ISBN 0-87341-667-8.
Nigel Wood, "Chinese Glazes". ISBN 90-5703-23-25.
My understanding is that the effect is as Lee Love suggests. The effect is
not due to gas bubbles but to the formation of two immiscible glasses, one
based on vitreous Silica and the other on vitreous Phosphorus Pentoxide.
Are you using treated or untreated Cornish Stone ?. The latter evolves
Fluorine when fired which may account for the generation of bubbles in your
glaze.
Best regards,
Ivor Lewis,
Redhill,
South Australia
May Luk on sun 21 feb 10
I just found an excellent example of an early Qing feather blue jun
flambe' glaze. It's from my father's side of China - Canton {Shiwan
kilns from south China}
http://www.ibankunited.com/phm/splendors.html
http://www.ibankunited.com/phm/images/p6splendors.jpg
Just for looksie!
May
--
http://twitter.com/MayLuk
Rikki Gill on mon 22 feb 10
Hi May,
Thanks for the post. Some of the images remind me of the Percival David
museum in London, which is now part of the
British Museum. Great stuff.
Thanks again,
Rikki
----- Original Message -----
From: "May Luk"
To:
Sent: Sunday, February 21, 2010 6:46 PM
Subject: Re: Chun glazes
>I just found an excellent example of an early Qing feather blue jun
> flambe' glaze. It's from my father's side of China - Canton {Shiwan
> kilns from south China}
>
> http://www.ibankunited.com/phm/splendors.html
> http://www.ibankunited.com/phm/images/p6splendors.jpg
>
> Just for looksie!
>
> May
>
>
> --
> http://twitter.com/MayLuk
Bill Merrill on mon 22 feb 10
"Making Pottery without a Wheel" by Carlton Ball has a great Chun glaze
in it ..It also has a Choy and another Celadon glaze in it. Chun has
8-9 ingredients in it (nothing exotic) but it does have about 2% barium
in it. It needs reduction or it's a little opaque. I use G-200 in the
glaze. I use the glaze with cobalt oxide and a little iron to produce a
rich dark blue glaze. I use it on large platters that are decorated
over with other glazes. I also us muriatic acid in the glaze to make it
thick . The glaze doesn't produce runs when I use it. There are 2
pictures of that glaze on 2 of my platters on Flickr.
http://www.flickr.com/photos/25594880@N04/=3D20
There are lots of other glazes at cone 10 and lower cone glazes also in
the Ball book
One of those glazes have minute bubbles to create a satin surface. Very
nice glazes.
If you contact Alfred University there is a Thesis by James Flaherty. He
is a graduate of KCAI and Alfred. His thesis is on Chun Glazes and has
his research was done on Chun glaze formulas. It just costs the
copying of the thesis. Not expensive.
=3D20
=3D20
=3D20
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