Wyndham Dennison on sat 9 aug 08
Date: Fri, 8 Aug 2008 16:04:06 +0930
From: Ivor and Olive Lewis
Subject: Copper Red, Red Hot
> In a section headed Colloidal Colour ( p 56 ) the natural history of
> this glaze style is described. Chemical decomposition of the original
> Copper compound as the kiln is heated under reducing condition leaves
> a residue of finely divided elemental metallic copper distributed
> throughout the glaze. Agglomeration of submicroscopic particles during
> cooling leaves a colloidal suspension. The final colour depends upon
> the size of these colloidal particles which cause interference with
> refracted and reflected light passing through the transparent base
> glaze.
Ivor I'm wondering have you read anything where tin plays a part in
helping where tin gives up an oxygen molecule then takes one from
copper,causing the copper to stay in a reduced state. Since tin is
usually is in a 3 to 1 or 4 to 1 ratio to copper I'm wondering if this
also has anything to do with the colloidal particles size you spoke of
above. Some of what I have read says that quick cooling through the"
*/Agglomeration of submicroscopic particles during
cooling leaves a colloidal suspension
/*Accounts for the particle size, sort of quick freeze so small particles.
I saw an interesting cross section of an old Chinese copper red shard
where 2 glazes were used. the second used to trap the first as the
copper migrated during firing. The shard show clay then clear or
slightly greenish a thin copper red then another clear which was the
exterior glaze. I know of several potters that have used this method
with success.
Thanks for the input Wyndham
jean szostek on sun 10 aug 08
hi ivor en wyndham,
i dont have that much experience, but i now that a quick cooling holds
indeed better the reds
and i did experiment with trapping glaze, for that i use a very stiff
celadon without iron, but it always
influenced the color
i'm curieus about the tin, wyndham, if ivor nows what the influence is.
greetings jean
----- Original Message -----
From: "Wyndham Dennison"
To:
Sent: Saturday, August 09, 2008 5:05 PM
Subject: copper reds once again
> Date: Fri, 8 Aug 2008 16:04:06 +0930
> From: Ivor and Olive Lewis
> Subject: Copper Red, Red Hot
>
>> In a section headed Colloidal Colour ( p 56 ) the natural history of
>> this glaze style is described. Chemical decomposition of the original
>> Copper compound as the kiln is heated under reducing condition leaves
>> a residue of finely divided elemental metallic copper distributed
>> throughout the glaze. Agglomeration of submicroscopic particles during
>> cooling leaves a colloidal suspension. The final colour depends upon
>> the size of these colloidal particles which cause interference with
>> refracted and reflected light passing through the transparent base
>> glaze.
> Ivor I'm wondering have you read anything where tin plays a part in
> helping where tin gives up an oxygen molecule then takes one from
> copper,causing the copper to stay in a reduced state. Since tin is
> usually is in a 3 to 1 or 4 to 1 ratio to copper I'm wondering if this
> also has anything to do with the colloidal particles size you spoke of
> above. Some of what I have read says that quick cooling through the"
>
> */Agglomeration of submicroscopic particles during
> cooling leaves a colloidal suspension
> /*Accounts for the particle size, sort of quick freeze so small particles.
>
> I saw an interesting cross section of an old Chinese copper red shard
> where 2 glazes were used. the second used to trap the first as the
> copper migrated during firing. The shard show clay then clear or
> slightly greenish a thin copper red then another clear which was the
> exterior glaze. I know of several potters that have used this method
> with success.
> Thanks for the input Wyndham
>
> No virus found in this incoming message.
> Checked by AVG - http://www.avg.com Version: 8.0.138 / Virus Database:
> 270.6.0/1602 - Release Date: 9/08/2008 13:22
>
>
>
jean szostek on thu 14 aug 08
hi ivor,
thanks for the reply, i still have to do mutch experiments on this mater
im going to make line blends with differant amounds of tin
anyway thank you for the replys
best reagards jean from little belgium
----- Original Message -----
From: "Ivor and Olive Lewis"
To:
Sent: Thursday, August 14, 2008 5:52 AM
Subject: copper reds once again
> Dear Jean Sostek,
> An interesting observation. << my experiences and they tells me that
> tin changes the color of my recipe and it is like you say ivor, that
> the red becomes more orange>>
> My prediction was very much a guess about what might happen to Tin
> Oxide and Copper Oxide fired in strongly reducing conditions.
> Books say that potters have used combinations of Tin and Copper for
> several centuries. It is known that when reduced the white surface of
> an opaque tin glaze will become a dirty grey.
> Without visual evidence from Electron Microscope studies I would
> consider much of the popular theory to be guesswork.
> Best regards,
> Ivor Lewis.
> Redhill,
> South Australia.
>
> No virus found in this incoming message.
> Checked by AVG - http://www.avg.com
> Version: 8.0.138 / Virus Database: 270.6.3/1610 - Release Date: 13/08/2008
> 16:14
>
>
>
Ivor and Olive Lewis on thu 14 aug 08
Dear Jean Sostek,
An interesting observation. << my experiences and they tells me that
tin changes the color of my recipe and it is like you say ivor, that
the red becomes more orange>>
My prediction was very much a guess about what might happen to Tin
Oxide and Copper Oxide fired in strongly reducing conditions.
Books say that potters have used combinations of Tin and Copper for
several centuries. It is known that when reduced the white surface of
an opaque tin glaze will become a dirty grey.
Without visual evidence from Electron Microscope studies I would
consider much of the popular theory to be guesswork.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
| |
|
