unrelated glazes at a vertical interface
The interactions at a vertical interface between glazes with a different balance
of oxides in the seger formula,
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 pair of glazes, though also
a saturated iron 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 hankPaper_Z1R_2C_1.
A thick glaze application resulted in large crystals forming in the
matrix glaze.
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 0.12
Al2O3 0.42
SiO2 2.7
molecular percent Silica 63%
Added:
1% Cobalt Carbonate
.67% Copper Carbonate
Metallic micro-crystals appear in this glaze if applied thickly. Here we
see acicular crystals growing
milk spreads by diffusion into the cup of coffee, the higher concentration of
alkaline earths and titanium
Here in the matrix glaze, we see an enhanced non-crystalline phase, a full
gloss glassy black phase
With the same background glaze and a different inlay glaze
alexanderBowl_Z1Y_0
Most of the increase in area covered by the inlay is attributable to crystal
growth in the matrix glaze,
The mask for the inlay is a simple wiggly line. After firing, the inlay is
considerably broadened.
thus different phase structure.
with no overlap whatever for large
parts of the design. The original mask for the inlay was a curved line,
nowhere more than half an inch thick.
is higher in alkaline earths containing both Barium and Strontium.
and a high alkaline earth glaze. Particularly
note the occurance of discrete acicular crystals on a glossy black background.
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
bowl with glaze iron_satIron_Z2W_Z2Z_0 and hankPaper_Z1R_2C_1
bowl is ~9 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 iron_satIron_Z2W_Z2Z_0 :
Na2O 0.50
Li2O 0.26
CaO 0.03
MgO 0.11
Fe2O3 0.22
Inlay 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
Remarks
in the interfacial region distinct from its
native metallic micro-crystals.
migrate from the inlay glaze into the
matrix, seeding additional phases in the matrix glaze.
of which only hints were otherwise seen.
the glossy black phase is minimally present.
and dissolution of the matrix glaze resulting
from diffusion of inlay glaze into the matrix.