Ilene Mahler on tue 5 jun 07
I am looking for a recipe for coleman porcelain..Veena had given me one =
at conference and it didn't make it home...Ilene in Conn Oh is anyone =
going to the crystal conference and opening at Bill Cambells' studio in =
Sept..looking for a roomate ride etc.....
Hank Murrow on wed 6 jun 07
On Jun 6, 2007, at 9:27 PM, Chris trabka wrote:
>
>
> I am on the hunt for blue celadon myself. I read John Britt's
> information and then looked at
> some old pots I have around the house. It seems that you can get a
> blue
> celedon with almost no titanium in the glaze (grolleg not EPK) or a
> bit of
> phosphor. I have tried a base green celedon and a line blend to see
> where
> there is a difference between a green celedon and a blue celedon. I
> was
> amazed at how much a slight difference in the irorn/phosphor makes
> in the
> final color. As little as 0.5% makes a huge difference in the final
> color.
>
> I started with a cone 11 clear glaze and substitued Grolleg for
> EPK. Yellow
> Iron Oxide was at 1%. In one set of tests I used only Kona. In the
> other
> set of tests I used only Custer. The Tri-Calcium-Phosphate ranged
> from 0%
> to 10%. The results were amazing.
>
> I believe that the results depend on the source of the chemicals
> (not all
> suppliers are the same), the firing schedule, and the clay body (I
> use a
> custom mix from Continental (50% domestic porcelain/50% white
> stoneware).
Dear Chris;
You can get closer to that ice blue if you use a Grolleg(or other
very low titania) body. American kaolins have too much titania for
the development of the blue you seek.
Cheers, Hank
www.murrow.biz/hank
Chris trabka on wed 6 jun 07
Ilene,
I am on the hunt myself. I read John Britt's information and then looked at
some old pots I have around the house. It seems that you can get a blue
celedon with almost no titanium in the glaze (grolleg not EPK) or a bit of
phosphor. I have tried a base green celedon and a line blend to see where
there is a difference between a green celedon and a blue celedon. I was
amazed at how much a slight difference in the irorn/phosphor makes in the
final color. As little as 0.5% makes a huge difference in the final color.
I started with a cone 11 clear glaze and substitued Grolleg for EPK. Yellow
Iron Oxide was at 1%. In one set of tests I used only Kona. In the other
set of tests I used only Custer. The Tri-Calcium-Phosphate ranged from 0%
to 10%. The results were amazing.
I believe that the results depend on the source of the chemicals (not all
suppliers are the same), the firing schedule, and the clay body (I use a
custom mix from Continental (50% domestic porcelain/50% white stoneware).
Here is my starting point.
potash 38
whiting 7
talc 7
dolomite 7
flint 26
grolleg 13
yellow iron (synthetic) 1%
tri-calcium-phosphate (bone ash) 0 to 10%
Best of luck.
Chris
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