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 has a substantially lower silica:alumina ratio than the inlay
glaze, as it has a lower
Diffusion of the higher alkali metals of the matrix glaze into the
lower alkali metal inlay
Several closeups of the interaction region of the two glazes are shown and,
for context, a picture of the pot.
The background glaze is longquan-iron-shino-PAl-Z37, 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 0.16
Al2O3 0.92
SiO2 3.56
molecular percent Silica 63.4%
K2O 0.09
Al2O3 0.43
SiO2 2.67
molecular percent Silica 64.7%
Note the needle crystals growing in the matrix glaze at the edge of the inlay.
For these two glazes, the driving force for interaction is the difference in
mobility of the
The original mask for the inlay was a simple curved line.
molecular percent of silica and significantly
higher molecular percent alumina.
is seen in the halo of dark brown framing
the inlay; and in the various mottled markings
of the thinner parts of an
otherwise ivory inlay glaze.
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 longquan-iron-shino-PAl-Z37 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 longquan-iron-shino-PAl-Z37 :
Na2O 0.39
Li2O 0.20
CaO 0.21
MgO 0.04
Fe2O3 0.12
Inlay Glaze
Empirical Formula alexanderBowl_0_Z1Y:
Na2O 0.05
CaO 0.70
MgO 0.16
Fe2O3 0.02
Remarks
matrix glaze and inlay glaze, together with the
difference in composition of the two glazes.
The inlay glaze has higher
alkaline earths, lower alumina, and no iron.