John Hesselberth on tue 1 feb 05
On Tuesday, February 1, 2005, at 08:46 AM, Daraburn@AOL.COM wrote:
> I am looking for a cone 6 translucent turquoise. Tried Val's
> Turquoise on
> porcelain and it is beautiful but is crazing. Has anyone had any
> success
> getting a translucent turquoise using MC6G bases? Or...anyone have
> revisions of
> Val's Turquoise for a better fit?
Hi Dawn,
You are faced with a real challenge here. Turquoise usually results
from copper being added to an alkaline glaze. Alkaline glazes, by their
nature, are prone to crazing on most clay bodies. There are a couple
possible solutions. The first (and probably easiest) is to get a
turquoise stain and add it to a more normal base glaze--one that fits
your clay body. Another is to examine strontium-based glazes. They seem
to give a near-alkaline color response in some circumstances. If you
try this route be prepared for a lot of testing. I suppose you might
also get their by sourcing some of the alkaline fluxes from lithium and
cut back on the KNa. Again, it may take lots of experiments to get
there. Maybe someone else will have better ideas. Good Luck.
Regards,
John
John Hesselberth
http://www.frogpondpottery.com
http://www.masteringglazes.com
Daraburn@AOL.COM on tue 1 feb 05
I am looking for a cone 6 translucent turquoise. Tried Val's Turquoise on
porcelain and it is beautiful but is crazing. Has anyone had any success
getting a translucent turquoise using MC6G bases? Or...anyone have revisions of
Val's Turquoise for a better fit?
Dawn in Tennessee
Anne Wellings on wed 2 feb 05
I've done most of my MC6G testing with Glossy Base 1. I get a nice
turquoise with 2-3% copper carb and 3-6% milled rutile. For more
translucency, use less rutile, and use the glaze thinner, but if on dark
clay, don't go too thin. There's no visible crazing on my clay. You might
get some good results with the other base recipes, too. It's just a matter
of lots of testing.
Anne in Olympia, Washington
On Tue, 1 Feb 2005 08:46:15 EST, Daraburn@AOL.COM wrote:
>I am looking for a cone 6 translucent turquoise. Tried Val's Turquoise on
>porcelain and it is beautiful but is crazing. Has anyone had any success
>getting a translucent turquoise using MC6G bases? Or...anyone have
revisions of
>Val's Turquoise for a better fit?
>
>Dawn in Tennessee
>
Kathy Greaves on wed 2 feb 05
The mc6g base that works best for me for transparency and noncrazing on =
porcelain is the high calcium semimatte base 2. To get a turquoise, I =
would try a line blend starting at 1% cobalt carb and 1% copper carb at =
each end, or, for a blind stab, 1/2% of each. Of course, if you have a =
favorite turquoise glaze try that colorant proportion. Glossy base =
glaze 1 also works well on porcelain, though it's a bit stiff with just =
copper added. Cobalt, iron and rutile all help the melt for me.
Hope this helps!
Kathy Greaves
Granite Bay, CA
| |
|
