Bret Hinsch on thu 30 nov 00
I admire the soft gentle colors of classical Chinese glazes, so I¡¦ve been reading up on how these were achieved. So far I¡¦ve come across three classic Chinese techniques for softening glaze colors: All three induce effects that scatter incoming light and create internal reflections, making the color more gentle and complex. These three effects are all present in Longquan (Lungchuan) celadon glaze, giving it that wonderful light jade color.
1. Tiny bubbles
2. Undissolved quartz particles
3. Tiny crystals (like anorthite, wollastonite, or cristobalite)
Does anyone know any general principles that I can use to modify my existing (non-celadon) glazes to create these effects? Is it possible to get these effects in any glaze, or are they only possible in a narrow range of glaze compositions?
What would these three effects do to the technical quality of a glaze (hardness, durability, toxic leaching, etc.)?
Also ¡V I notice that some of Hamada¡¦s colors have a gentle whitish tinge that I really like. I¡¦ve only seen pictures in books, so I¡¦m not sure how he achieved this whitening. Does anyone know what techniques he used to soften his colors so beautifully? Did he just add some opacifier, or is there some ancient Japanese secret involved?
Thanks for sharing your wisdom!
Bret
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philrogers pottery on thu 30 nov 00
Bret,
I can tell you that the white glaze used by Hamada is called Nuka in =
Japan and is white because of a surfeit of Silica un-dissolved in the =
glaze. In the east the silica came largely from Rice Husk ash. In the =
west we use Flint or Quartz as a substitute, I favour Flint. Try equal =
proportions of Flint, Ash and Cornish Stone as a starting point. It is =
difficult to melt and you may need to decrease the flint a little and =
increase the ash a little to make it work below Cone 13.
Bone ash is another material you can try adding to your existing =
celadons. The Phosphorus is a glass forming oxide like silica but the =
two do not mix. The Phosphorus glass is held within the silica glass =
like oil in a shaken salad dressing and creates a chun or flush effect ( =
But not always!) Try it.
Personally, I don't think there is anything to worry about regarding =
glaze toxicity. There is nothing harmful in these glazes. As for =
durability, who knows! The Chinese, Korean and Japanese examples seem to =
have lasted! Hamada's glazes were, and still are, so beautiful who cares =
if their not up to some industrial standard. How long do you want!?
Phil.
Phil and Lynne Rogers,
Lower Cefn Faes,
RHAYADER.
Powys. LD6 5LT.
Tel/fax. (44) 01597 810875.
philrogers@ntlworld.com
----- Original Message -----=20
From: Bret Hinsch=20
To: CLAYART@LSV.CERAMICS.ORG=20
Sent: Thursday, November 30, 2000 4:45 PM
Subject: softening colors - Longqquan, Hamada
=20
I admire the soft gentle colors of classical Chinese glazes, so =
I=A1=A6ve been reading up on how these were achieved. So far I=A1=A6ve =
come across three classic Chinese techniques for softening glaze colors: =
All three induce effects that scatter incoming light and create =
internal reflections, making the color more gentle and complex. These =
three effects are all present in Longquan (Lungchuan) celadon glaze, =
giving it that wonderful light jade color.
=20
1. Tiny bubbles
2. Undissolved quartz particles
3. Tiny crystals (like anorthite, wollastonite, or cristobalite) =
=20
=20
Does anyone know any general principles that I can use to modify my =
existing (non-celadon) glazes to create these effects? Is it possible =
to get these effects in any glaze, or are they only possible in a narrow =
range of glaze compositions?
=20
What would these three effects do to the technical quality of a glaze =
(hardness, durability, toxic leaching, etc.)? =20
=20
Also =A1V I notice that some of Hamada=A1=A6s colors have a gentle =
whitish tinge that I really like. I=A1=A6ve only seen pictures in =
books, so I=A1=A6m not sure how he achieved this whitening. Does anyone =
know what techniques he used to soften his colors so beautifully? Did =
he just add some opacifier, or is there some ancient Japanese secret =
involved? =20
=20
Thanks for sharing your wisdom!
Bret
-------------------------------------------------------------------------=
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Get more from the Web. FREE MSN Explorer download : =
http://explorer.msn.com
=
_________________________________________________________________________=
_____ Send postings to clayart@lsv.ceramics.org You may look at the =
archives for the list or change your subscription settings from =
http://www.ceramics.org/clayart/ Moderator of the list is Mel Jacobson =
who may be reached at melpots@pclink.com.=20
Bret Hinsch on fri 1 dec 00
Thanks for the good advice, Phil!
I tried making a synthetic Nuka awhile back and ended up with a horrible dry matt, albeit with an extraordinary white color. Now I'm determined to go back to my test tiles and keep slaving away until I get it right. It sounds like the the wonderful effect of Nuka is achieved in the same way as it was Song dynasty glazes - all those suspended particles create subtle colors.
But what about deliberately introducing bubbles or microscopic crystals into a glaze? Does anyone have any good ways of reformulating an ordinary glossy glaze to produce these effects?
If I just slow down my cooling, will that always grow crystals in a glaze? I know that the original Song dynasty Chun glazes were originally fired for ten days (!!!) Those tiny crystals are probably due to an incredibly slow cooling time. When making flower pots for the emperor of China, no effort was too much trouble. But times have changed. I'd prefer something a bit easier, and in oxidation. Maybe a few more hours in the cool down phase would get some micro-crystals going in an ordinary (non-Chun, non-celadon) oxidation glaze?
Bret
>From: philrogers pottery
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: softening colors - Longqquan, Hamada
>Date: Thu, 30 Nov 2000 22:29:03 -0000
>
>Bret,
>
>I can tell you that the white glaze used by Hamada is called Nuka in Japan and is white because of a surfeit of Silica un-dissolved in the glaze. In the east the silica came largely from Rice Husk ash. In the west we use Flint or Quartz as a substitute, I favour Flint. Try equal proportions of Flint, Ash and Cornish Stone as a starting point. It is difficult to melt and you may need to decrease the flint a little and increase the ash a little to make it work below Cone 13.
>
>Bone ash is another material you can try adding to your existing celadons. The Phosphorus is a glass forming oxide like silica but the two do not mix. The Phosphorus glass is held within the silica glass like oil in a shaken salad dressing and creates a chun or flush effect ( But not always!) Try it.
>
>Personally, I don't think there is anything to worry about regarding glaze toxicity. There is nothing harmful in these glazes. As for durability, who knows! The Chinese, Korean and Japanese examples seem to have lasted! Hamada's glazes were, and still are, so beautiful who cares if their not up to some industrial standard. How long do you want!?
>
>Phil.
>
>Phil and Lynne Rogers,
>Lower Cefn Faes,
>RHAYADER.
>Powys. LD6 5LT.
>Tel/fax. (44) 01597 810875.
>philrogers@ntlworld.com
>
> ----- Original Message -----
> From: Bret Hinsch
> To: CLAYART@LSV.CERAMICS.ORG
> Sent: Thursday, November 30, 2000 4:45 PM
> Subject: softening colors - Longqquan, Hamada
>
>
>
> I admire the soft gentle colors of classical Chinese glazes, so I¡¦ve been reading up on how these were achieved. So far I¡¦ve come across three classic Chinese techniques for softening glaze colors: All three induce effects that scatter incoming light and create internal reflections, making the color more gentle and complex. These three effects are all present in Longquan (Lungchuan) celadon glaze, giving it that wonderful light jade color.
>
>
>
> 1. Tiny bubbles
>
> 2. Undissolved quartz particles
>
> 3. Tiny crystals (like anorthite, wollastonite, or cristobalite)
>
>
>
> Does anyone know any general principles that I can use to modify my existing (non-celadon) glazes to create these effects? Is it possible to get these effects in any glaze, or are they only possible in a narrow range of glaze compositions?
>
>
>
> What would these three effects do to the technical quality of a glaze (hardness, durability, toxic leaching, etc.)?
>
>
>
> Also ¡V I notice that some of Hamada¡¦s colors have a gentle whitish tinge that I really like. I¡¦ve only seen pictures in books, so I¡¦m not sure how he achieved this whitening. Does anyone know what techniques he used to soften his colors so beautifully? Did he just add some opacifier, or is there some ancient Japanese secret involved?
>
>
>
> Thanks for sharing your wisdom!
>
> Bret
>
>
>
>------------------------------------------------------------------------------
> Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com
>
>
> ______________________________________________________________________________ Send postings to clayart@lsv.ceramics.org You may look at the archives for the list or change your subscription settings from http://www.ceramics.org/clayart/ Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
Get more from the Web. FREE MSN Explorer download : http://explorer.msn.com
Lee Love on fri 1 dec 00
Brett,
I am not sure, but maybe you are talking about the Nuka (Rice =
hull ash) glaze that Hamada used. It gets its opacity from the silica =
in the ash. Phil Roger's has a nice synthetic recipe for Nuka in his =
Ash Glazes book. Before I came to Japan, I used it in Minnesota, with =
Temmoku, Kaki and a Limestone base. His recipe has no solubles, but =
that is easy to remedy by adding a little soda ash. I had good luck =
with it. Nuka is one of my favorite glazes here, along with the =
standard wood ash/ball clay glaze, Temmoku, Kaki and of course, Shino.
--
Lee Love
Mashiko JAPAN Ikiru@kami.com =20
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----- Original Message -----=20
From: Bret Hinsch=20
Also =A1V I notice that some of Hamada=A1=A6s colors have a gentle =
whitish tinge that I really like. I=A1=A6ve only seen pictures in =
books, so I=A1=A6m not sure how he achieved this whitening. Does anyone =
know what techniques he used to soften his colors so beautifully? Did =
he just add some opacifier, or is there some ancient Japanese secret =
involved? =20
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