Migrating abutting glazes
The interface of adjacent glazes.
Several closeups of the interaction region of the two glazes are shown and,
for context, a picture of the pot.
The background glaze is hankPaper_Z1R_2C_1; the foreground design is
glazed with iron_8_R_C10_13PSi.
The design is created by adhering a mask and then applying the main
glaze. After drying, the entire pot is coated in wax,
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 1750 deg F then a half hour hold at 1750 deg F
300 deg F an hour to 1700 deg F then a Three 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 0.12
Al2O3 0.42
SiO2 2.7
molecular percent Silica 63%
Added:
1% Cobalt Carbonate
.67% Copper Carbonate
K2O 0.11
Al2O3 0.56
SiO2 3.12
molecular percent Silica 63%
The
inlay glaze is higher in alkali metals, silica and alumina.
Silica and alkali metals migrate from the inlay into the matrix, while
alkaline earths migrate in the opposite
Most of the inlay has been consumed by the mongrel interface composition. The
inlay mask had been continuous,
Radially arrayed needle crystals have grown in the interaction region where the
two glazes have grown together.
then the mask is removed
and the open area filled in with a second glaze.
Close up Images of the interaction region
Image of the piece
bowl with glaze glaze hankPaper_Z1R_2C_1 and inlay iron_8_R_C10_13PSi
bowl is ~7 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Background glaze
Empirical Formula hankPaper_Z1R_2C_1 :
Na2O 0.12
Li2O 0.05
CaO 0.14
MgO 0.02
BaO 0.31
SrO 0.24
TiO2 0.14
Inlay Glaze
Empirical Formula iron_8_R_C10_13PSi :
Na2O 0.45
Li2O 0.25
CaO 0.17
MgO 0.02
Fe2O3 0.28
Remarks
direction, from the matrix into the
inlay. In both cases, as ink spreads in water, so migration is against
the
compositional gradient, from high concentration to low concentration.
connecting the current dark glossy pools.
The brown/yellow areas cover regions through which
the inlay had once
passed.