unrelated glazes at a vertical interface
Dissimilar glazes interacting at a vertical interface.
The matrix (i.e. background) glaze and inlay glaze overlap by no more
than an eighth of an inch before firing,
The matrix glaze is high in iron, alumina and alkali metals. The inlay glaze, by
contrast,
Similar artifacts are seen
here in the interaction between an unrelated background glaze, and the
same foreground glaze.
Several closeups of the interaction region of the two glazes are shown and,
for context, a picture of the pot.
The background glaze is iron_satIron_Z2W_Z2Z_0, the inlay design is
glazed with satIron_ZG_1O_1Q_1MFe.
The design is created by adhering a mask and then applying the main
glaze. After drying, the mask is removed
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 0.10
Al2O3 0.66
SiO2 3.4
molecular percent Silica 64.3%
K2O .24
Al2O3 .47
SiO2 3.17
molecular percent Silica 66%
The higher concentrations of Calcium and Phosphorus migrate from the inlay
glaze into the matrix, seeding
In the interaction region, we see globules of a non-crystalline phase, yellow and
red colored regions like oil
Most of the increase in area covered by the inlay is attributable to
dissolution of the matrix glaze
The mask for the inlay is a simple wiggly line. After firing, the inlay is
considerably broadened.
with no overlap whatever for large
parts of the design. The original mask for the inlay was a curved line,
nowhere more than three eights of an inch thick.
is higher in Calcium, and contains Phosphorus.
and the open area filled in with a
second glaze, using a bulb syringe.
Close up Images of the interaction region
Image of the piece
mug with glaze iron_satIron_Z2W_Z2Z_0 and inlay satIron_ZG_1O_1Q_1MFe
mug is ~4.5 inches in high
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 iron_satIron_Z2W_Z2Z_0 :
Na2O 0.50
Li2O 0.26
CaO 0.03
MgO 0.11
Fe2O3 0.22
Inlay Glaze
satIron_ZG_1O_1Q_1MFe :
Na2O .22
Li2O .24
CaO .16
MgO .14
Fe2O3 .09
P2O5 .04
Remarks
additional phases in the matrix glaze.
in salad dressing. These globules have
sharp boundaries and are not otherwise seen in either matrix or inlay glazes.
resulting from diffusion of inlay glaze into
the matrix.