Lili Krakowski on sun 16 dec 07
Randy:
Ok. your recipe and unity formula go as follows:
Amount Ingredient
47.3 Nepheline Syenite
27 Gerstley Borate--1999
20.3 Silica
5.4 Kaolin--EPK
100 Total
Additives
6 Rutile
1 Cobalt Carbonate
Unity Oxide
.418 Na2O
.112 K2O
.006 MgO
.464 CaO
1.000 Total
.702 Al2O3
.476 B2O3
.002 Fe2O3
4.553 SiO2
.001 TiO2
0 P2O5
First: June of course is right that there are plenty of recipe for blue out
there.
But as you seem eager to learn something new, AND we are having a
snowstorm....
If I were doing this I would reduce the calcium in favor of the alkalis.
Rhodes tells us that "in alkaline glazes, cobalt oxide produces an extremely
brilliant blue." Ok. You are using the cabonate no doubt, but alkalis still
do their thing,.Hopper says that with strontium and in alkaline glazes one
gets a brilliant ultramarine blue. And Cooper says that 2%-3% zinc heighten
the intensity of the color...
Then,devoted as I am to titanium one of the most undereappreciated glaze
ingredients, I would kick the rutile out entirely. Rutile does not contain
much iron....but why use it when you want no iron? And titanium the books
tell us tends ot make cobalt greenish.
Why would you add bone ash?
I would try these recipes, both of which are imperfect in regards to my
"ideal" but possible with readily available materials:
New Blue 1
Neph Sy 28
FF 3185 41
Frit 3134 2
Silica 21
ZnO 2
Strontium 5
Bentonite 3 or more %--work pragmatically
Na2O .491
K2O .197
MgO .010
CaO .047
SrO .136
ZnO.119
Al2O3 .495
B2O3 .386
SiO2 .4.071
May well craze, but test.
This reduces your calcium and magnesium, the alumina, boron and silica
remaining in your "ballpark"--albeit they seem high to me. If they work
they work.
I would test with small additions of tin and of zirconium...I know tin is
costly but in the total picture of the potting enterprise it is the least of
our worries.
Please let us know what happens.
Lili Krakowski
Be of good courage
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