An oil spot glaze in a hotter firing
An oil spot glaze results from the popping of bubbles at its surface, revealing
the micro-crystals which had
The oil spot
glaze
jingdeshen-iron-7-13-MLi-2 at cone 10 has bubbles just beginning to
pop.
In this hotter firing to cone 11.5, that glaze, jingdeshen-iron-7-13-MLi-2,
the oil spots are replaced by the
The plate has a leaf print. Several closeups of the surface of the glaze,
including images of the interaction
A leaf is softened by soaking in water laced with trisodium phosphate. After
the pot is glazed, the leaf is pressed
plate is ~ 7 inches in diameter
The cone 11 is down past the bottom of the cone pat, both cone 12 and cone 13
are tipped.
150 deg F an hour to 250 deg F
400 deg F an hour to 1800 deg F
300 deg F an hour to 1965 deg F
120 deg F an hour to 2250 deg F
30 deg F an hour to 2325 deg F with a 20 minute hold at 2325 deg F
300 deg F an hour to 1800 deg F then a 2 hr hold at 1800 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
K2O 0.35
Al2O3 0.53
SiO2 3.58
molecular percent Silica 66.5%
K2O 0.43
Al2O3 0.54
SiO2 3.33
molecular percent Silica 48%
grown within. When the glaze is fired past
the point where the bubbles had all popped, what happens?
rings of craters, the artifacts which remain
after the oil spots have collapsed.
between the glaze and the wash over
the leaf embedded in the glaze are shown. A picture of the plate is also
shown.
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.
Images of the surface and its interaction with the leaf wash
Image of the glaze jingdezhen-iron-7-13-MLi-2 with leaf wash leaf_Z3K
oxidation firing to cone 11.5 in an electric kiln
Firing profile
Up Fire profile cone 11.5
Down Fire Profile cone 11.5
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Background Glaze:
Empirical Formula jingdezhen-iron-7-13-MLi-2:
Na2O 0.11
CaO 0.53
MgO 0.01
Fe2O3 0.12
P2O5 0.15
Empirical Formula of leaf wash glaze leaf_Z3K:
Na2O 0.53
CaO 0.04
P2O5 0.15