cobalt pink
This glaze, zincSr_Z3T_PZn_PSi is a near neighbor of zincSr_Z3W_0
shown here .
In the invert firing, described below, it shows an even more saturated pink
than did zincSr_Z3W_0.
Invert Firing:
The upfire protocol is as usual.
The downfire drops with a hold at 1650 degF, then rises back up with a hold at
1850 deg F, then back down
The reasoning behind inversion of the order of the downfire holds is discussed
here .
The design is created by adhering a mask and then applying the main
glaze. After drying,
bowl is ~6 inches in diameter.
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 1650 deg F then a 3 hr hold at 1650 deg F
300 deg F an hour to 1850 deg F then a 2 hr hold at 1850 deg F
300 deg F an hour to 1700 deg F then a 2 hr hold at 1700 deg F
K2O 0.16
Al2O3 0.52
SiO2 3.20
molecular percent Silica 67.8%
Added:
2.5% Cobalt Carbonate
K2O 0.18
Al2O3 0.64
SiO2 3.54
molecular percent Silica 64.9%
Comparing zincSr_Z3T_PZn_PSi to zincSr_Z3W_0; it has the same total alkali
metals, similar alumina, with higher
with a hold at 1700 deg F.
the mask is removed and the open area filled in with a
second glaze, using a bulb syringe
with a needle applicator.
Image of the glaze zincSr_Z3T_PZn_PSi
oxidation firing to cone 10 in an electric kiln
Firing profile - Invert Firing
Up Fire profile cone 10
Down Fire Profile cone 10
Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.
glaze composition
Empirical Formula zincSr_Z3T_PZn_PSi:
Na2O 0.31
CaO 0.02
MgO 0.17
SrO 0.15
ZnO 0.19
Inlay Glaze:
Empirical Formula inlay hiAlk_Z3P_Z3V_0:
Na2O 0.41
CaO 0.31
MgO 0.10
P2O5 0.07
TiO2 0.21
Remarks
silica and small shifts in alkaline
earths.