Gary Elfring on tue 4 may 04
I have been working with rare earths to color some of my Celadon base
glazes (minus the iron). I'm firing in a gas kiln to cone 10
(reduction).
My problem is that the Neodymium Oxide glazes give totally uneven
coloring. It looks as if the glaze is reduction sensitive, even though
from what I have read, it is not supposed to be. Here's a link to a
sample plate so you can see what I mean:
http://www.elfringpottery.com/gif/plate.jpg
I am using Tom Coleman's base clear glaze and adding 6% Neodyium Oxide
plus 0.5% Copper Carbonate. I use Song porcelain as my clay (hopefully
no iron in it.) I would like to get reliable continuous
red/magenta colors.
My questions are- what is the copper carbonate for? My reading
suggests that Neodymium is not very soluble in a typical Celadon
glaze- but if it isn't soluble, why do I get the color at all? The
clear glazes that Neodymium is soluble in aren't food safe, so I want
to avoid that.
Any help appreciated!
--
Best regards,
Gary
Des & Jan Howard on wed 5 may 04
Gary
To me the glaze on the plate is what could be expected from
a 0.5% copper carbonate glaze, (our intense red has 0.42%).
The clear/pale green area is a "cooked out" spot we associate
with flame blast. The blue ring is a chun effect which would
occur with no colouring oxides in the glaze at all.
Dunno what the neodymium did/does, prolly reduces excessive bank accounts :)
Des
Gary Elfring wrote:
> I have been working with rare earths to color some of my Celadon base
> glazes (minus the iron). I'm firing in a gas kiln to cone 10
> (reduction).
>
> My problem is that the Neodymium Oxide glazes give totally uneven
> coloring. It looks as if the glaze is reduction sensitive, even though
> from what I have read, it is not supposed to be. Here's a link to a
> sample plate so you can see what I mean:
>
> http://www.elfringpottery.com/gif/plate.jpg
>
> I am using Tom Coleman's base clear glaze and adding 6% Neodyium Oxide
> plus 0.5% Copper Carbonate. I use Song porcelain as my clay (hopefully
> no iron in it.) I would like to get reliable continuous
> red/magenta colors.
>
> My questions are- what is the copper carbonate for? My reading
> suggests that Neodymium is not very soluble in a typical Celadon
> glaze- but if it isn't soluble, why do I get the color at all? --
Des & Jan Howard
Lue Pottery
LUE NSW 2850
Australia
Ph/Fax 02 6373 6419
http://www.luepottery.hwy.com.au
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