Reacting glazes at a vertical interface
Glazes interacting at a vertical interface.
The matrix (i.e. background) glaze and inlay glaze do not overlap before
firing.
The matrix glaze is high in alkali metals, which results in a low viscosity,
fluid glaze.
The result of the high fluidity of the matrix is a greatly increased flow in
the inlay, broadening
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_Alex_0_Z36, the inlay design is
glazed with alexanderBowl_0_Z1Y.
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 0.08
Al2O3 0.60
SiO2 3.24
molecular percent Silica 64.6%
K2O 0.09
Al2O3 0.43
SiO2 2.67
molecular percent Silica 64.7%
For these two fluid glazes, the driving force for interaction is the high
mobility of the matrix glaze
The extra mass of inlay glaze added to the generous supply of background glaze
resulted in a substantial flow at
The original mask for the inlay was a simple curved line, nowhere
more than three eights of an inch thick.
The inlay glaze is high in alkaline earths and has higher
viscosity than the matrix glaze. The inlay glaze is
lower in alumina and
silica than the matrix glaze, which increases the fluidity of the mixture
in the interaction region. That increased fluidity encourages
crystal growth. This is seen in the line of acicular
crystals growing at
the edge of the inlay. These seem to be the same crystals as grow in the
matrix glaze.
the interaction region. The result is that
the general form of the inlay together with the interaction region
is only
minimally related to the original masks.
and the open area filled in with a
second glaze, using a bulb syringe with a needle applicator.
Close up Images of the interaction region
--
Image of the piece
mug with glaze iron_Alex_0_Z36 and inlay glaze alexanderBowl_0_Z1Y.
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_Alex_0_Z36 :
Na2O 0.38
Li2O 0.15
CaO 0.29
MgO 0.10
Fe2O3 0.16
P2O5 0.03
Inlay Glaze
Empirical Formula alexanderBowl_0_Z1Y:
Na2O 0.05
CaO 0.70
MgO 0.16
BaO
Fe2O3 0.02
Remarks
together with the difference in composition
of the two glazes. The inlay glaze has higher alkaline earths, and lower
alumina and silica.
the bottom of the pot. The pot stuck
to the kiln shelf.