Nickel Colors
This glaze has scattered micro-crystalline inclusions in a transplucent magenta
matrix. The color is the result of the addition of nickel oxide.
This glaze is derived by a circuitous route from the glaze number 404 in
Emmanuel Cooper book
inside of bowl:
Outside of bowl:
150 deg F an hour to 250 deg F
400 deg F an hour to 1800 deg F
300 deg F an hour to 2050 deg F
120 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F
300 deg F an hour to 1750 deg F then a half hour hold at 1750 deg F
300 deg F an hour to 1700 deg F then a Three hour hold at 1700 deg F
25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F
This glaze has 1% Nickel Oxide added
K2O 0.12
Al2O3 0.41
SiO2 2.72
molecular percent Silica 65.7%
The spirit of the original cooper glaze is low alkali metals; this glaze has
alkali metals 0.16 compared to 0.12 of the original
The ZnO in the original glaze is replaced by BaO, and alumina and
silica are significantly higher.
This glaze is separated into two distinct phases, a microcrystalline phase
which is prominent where the glaze is thickly applied,
The nickel oxide colors the microcrystalline glaze and matrix distinct shades
of magenta.
Note that this glaze has minimal CaO, only that CaO and MgO which are present
in all clays and feldspars.
"The Potters Book of Glaze Recipes".
cooper_404_0_Z2N_0
bowl is ~3 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Empirical Formula glaze cooper_404_Z2F_1 :
Na2O 0.04
CaO 0.01
MgO 0.01
BaO 0.82
Remarks
Cooper glaze.
and a waxy matte
matrix where the glaze is thin.
Previous work on glazes colored with nickel oxide
has convinced me that CaO promotes gray and brown colors.