fall colors from cobalt
This glaze, zincSr_Z3S_0, is a descendant of zincSr_Z3R
shown here .
Some of the alkali metals were replaced by MgO. Otherwise the empirical is
unchanged from the glaze
There are fewer crystals, though the mol fraction of ZnO, which I'd thought
the source of the crystals hasn't changed.
The colors of the surface micro-crystals are those of fall, pale peach and
golden yellow. The light colored
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 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 0.10
Al2O3 0.51
SiO2 2.75
molecular percent Silica 64.5%
Added:
2.5% Cobalt Carbonate
K2O 0.09
Al2O3 0.71
SiO2 3.98
molecular percent Silica 65.5%
seen in the note.
surface crystals are all that remain of
crystals. The aqua matrix glaze is without crystals. As is seen on the
back
of the bowl, where the throwing lines are prominent, the colors of
the crystals are determined by
the glaze thickness.
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_Z3S_0
inside
outside
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_Z3S_0:
Na2O 0.30
CaO 0.01
MgO 0.24
SrO 0.15
ZnO 0.20
Empirical Formula of inlay glaze satIron_mashiko_neph_1H_0MLi:
Na2O 0.46
CaO 0.43
MgO 0.02
Fe2O3 0.25
P2O5 0.12