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 satIron_ZL_3, the foreground design is
glazed with paperWhite_ZV_3_Z2H. paperWhite_ZV_3_Z2H contains cobalt.
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 0.07
Al2O3 0.79
SiO2 3.30
molecular percent Silica 62.9%
K2O 0.05
Al2O3 0.6
SiO2 3.2
molecular percent Silica 64.6%
Added:
1% cobalt carbonate
The pale blue shadow framing much of the inlay marks the original position of
the design.
There are three distinct rings between the inner region of the inlay glaze and
the outer region of background matrix.
opaque pale blue
The golden brown crystals are found scattered across the background matrix.
The background glaze has CaO, and MgO, of which the inlay
has only a trace of either. Additionally, the background
Likely the CaO, MgO, Fe2O3 and Na2O diffused from high concentration in the
matrix to low concentration in the inlay,
Many oxides moving in both directions, each with its own rate of
flow would account for the final result of three
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
plate with glaze satIron_ZL_3 and inlay glaze paperWhite_ZV_3_Z2H
plate is ~10 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
satIron_ZL_3:
Na2O 0.44
Li2O 0.21
CaO 0.15
MgO 0.13
Fe2O3 0.1
P2O5 0.05
Inlay glaze
Empirical Formula paperWhite_ZV_3_Z2H :
Na2O 0.15
Li2O 0.20
CaO 0.02
MgO 0.02
BaO 0.28
SrO 0.28
TiO2 0.16
Remarks
Starting at the edge of the inlay,
they are characterized as:
opaque dark brown
golden brown crystals
glaze is
substantially higher in Fe2O3 and Na2O than the inlay glaze. The inlay on the
other hand,
has substantial BaO and SrO, of which the background has
none.
while both BaO and SrO diffused
from inlay into background.
distinct rings in
the interaction region.