cobalt colors again
These glazes, zincSr_Z3U_0, zincSr_Z3U_1 and zincSr_Z3U_2, are descendants of
zincSr_Z3S_0
The same collection of cobalt micro-crystals are seen in zincSr_Z3U_0 and
The surface of zincSr_Z3U_2 is dominated by a covering of peach/tan colored
micro-crystals
These three glazes have similar compositions, though there are slight shifts
in alkalinity, relative
These three glazes differ in fluidity, zincSr_Z3U_0 has high surface tension,
seen in the shape of the
The design is created by adhering a mask and then applying the main
glaze. After drying,
bowls are ~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 1850 deg F then a 2 hour hold at 1850 deg F
300 deg F an hour to 1750 deg F then a 1 hour hold at 1750 deg F
300 deg F an hour to 1700 deg F then a 3 hour hold at 1700 deg F
25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F
K2O 0.18
Al2O3 0.50
SiO2 2.73
molecular percent Silica 64.4%
Added:
2.5% Cobalt Carbonate
K2O 0.13
Al2O3 0.53
SiO2 2.78
molecular percent Silica 64.5%
Added:
2.5% Cobalt Carbonate
K2O 0.13
Al2O3 0.51
SiO2 2.77
molecular percent Silica 64.6%
Added:
2.5% Cobalt Carbonate
K2O 0.30
Al2O3 0.72
SiO2 3.59
molecular percent Silica 62.7%
shown here .
zincSr_Z3U_1, though the glazes are dissimilar.
almost absent in zincSr_Z3U_0 and zincSr_Z3U_1.
proportion of K2O:Na2O, and alumina. With no
large differences, these small collective differences result
in a large
shift in the proportion of the various micro-crystals observed.
divots at pinholes. zincSr_Z3U_1 and
zincSr_Z3U_2 slide down a bit at the upper edge. More movement
in a
glaze, encourages greater crystal growth.
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_Z3U_0
Image of the glaze zincSr_Z3U_1
Image of the glaze zincSr_Z3U_2
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.
glaze composition
Empirical Formula zincSr_Z3U_0:
Na2O 0.24
CaO 0.02
MgO 0.22
SrO 0.17
ZnO 0.17
Empirical Formula zincSr_Z3U_1:
Na2O 0.34
CaO 0.02
MgO 0.20
SrO 0.14
ZnO 0.17
Empirical Formula zincSr_Z3U_2:
Na2O 0.30
CaO 0.02
MgO 0.24
SrO 0.14
ZnO 0.17
Empirical Formula of inlay glaze epk_tsp_rutile:
Na2O 0.66
CaO 0.03
MgO 0.01
P2O5 0.19
TiO2 0.22