Effect of Inverted Down-Firing
The appearance of a saturated iron glaze is transformed by an inversion of the
order of the downfire holds
Both Firing 1 and Firing 2 have the same upfire protocol.
Firing 1:
The downfire is my regular down firing, with holds at 1850 degF,
1750 degF, 1700 degF and 1650 degF.
Firing 2:
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 inlay design is created by adhering a mask and then applying the main
glaze. After drying,
The leaf print is created with a leaf which is softened by soaking in
water laced with trisodium phosphate.
plate is ~ 8.5 inches in diameter
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 hr hold at 1850 deg F
300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F
300 deg F an hour to 1700 deg F then a 3 hr hold at 1700 deg F
25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F
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 0.15
Al2O3 0.74
SiO2 3.21
molecular percent Silica 61.3%
K2O 0.18
Al2O3 0.64
SiO2 3.54
molecular percent Silica 64.9%
in the firing. The clusters of coppery
colored micro-crystals are replaced by a lusterous metallic
surface.
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.
After the pot is glazed, the leaf
is pressed into the glaze. When the glaze dries, a swatch of plate including
the leaf is coated with wax. When the wax is dry, the leaf is removed
and the indentations
in the glaze are coated with a very thin layer of an
underfired glaze.
Image of the glaze satIron_ZG_Z3N_Z3T_MSi in Firing 1
Image of the glaze satIron_ZG_Z3N_Z3T_MSi in Firing 2
oxidation firings to cone 10 in an electric kiln
Firing 1 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Firing 2 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Empirical Formula satIron_ZG_Z3N_Z3T_MSi:
Na2O 0.48
CaO 0.27
MgO 0.10
Fe2O3 0.22
P2O5 0.07
Inlay Glaze:
Empirical Formula inlay hiAlk_Z3P_Z3V_0:
Na2O 0.41
CaO 0.31
MgO 0.10
P2O5 0.07
TiO2 0.21