June Perry on mon 18 dec 00
Hi Mel:
Why fool around with the slip when you can just use a nice navy blue glaze.
Here's a formula that I recently made and I have only tested it on a small
stoneware tile and over porcelain slip (same one you posted). It is a very
nice navy blue with other subtle underlying colors from the other colorants.
It's a hair brighter on porcelain or over porcelain slip. It's not a dull,
dark grayish blue nor is it a bright Noxzema. It's just a rich navy.
Excuse all my numbers and letters, but it's my way of keeping track of my
recipes and revisions!
JP#2651ARevised
29.41. F4 Sodaspar
14.32 Whiting
5.38 Barium Carbonate
15.88 Grolleg
35.02 Silica
Add: Rutile(I use dark) 5%, Cobalt oxide 2%, Copper oxide 2%
Silica Alumina Ratio 8.73 Expansion 6.93
If you want to raise the Al2O3 SiO2 ratio you can add 5% more silica. That
will give you a ration of 9.46 and lowers the expansion of 6.74
This recipe with or without the extra silica is within the limits for a cone
10 copper bearing glaze, as per Insight.
The version listed, will give a buttery shine at cone 10.
You might want to do a test with the rutile as given, but skip the copper and
up the cobalt to about 3 if you don't like the tiny bit of green that can
show up on the edges and rims when thinner.
I like the copper in here because it, along with the rutile, gives the glaze
a lot of depth and character.
The glaze is pretty well balanced and within cone 10 limits. I put in
enough alumina and silica (about .45 alumina and 3.92 silica. The barium, I
think, would be ok, but you can always do the strontium carb (75% of the
barium carb) substitute if you don't use barium.
Let me know how it works for you if you decide to try it.
Warm regards,
June
| |
|
