Interacting micro-crystalline glazes at a vertical interface

Micro-crystalline Glazes interacting at a vertical interface.

The matrix (i.e. background) glaze and inlay glaze do not overlap before firing.

Several closeups of the interaction region of the two glazes are shown and, for context,
a picture of the pot. An image of the inlay glaze is shown separately.

The background glaze is brightMatte_MSn, the inlay design is glazed with iron_Alex_1_1.

The design is created by adhering a mask and then applying the main glaze. After drying,
the mask is removed 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

full view

full view

full view

full view



Image of the inlay glaze iron_Alex_1_1

full view

bowl is ~3 inches in diameter



Image of the piece

full view

bowl with glaze brightMatte_MSn and inlay glaze iron_Alex_1_1.

bowl is ~7 inches in diameter



oxidation firing to cone 10 in an electric kiln

Firing profiles

Up Fire profile

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

Down Fire Profile

300 deg F an hour to 1850 deg F then a two hour hold at 1850 deg F

50 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

Clay body is a grolleg porcelain from Tacoma Clay Art Center.



glaze compositions

Background glaze

Empirical Formula brightMatte_MSn :

K2O        0.16
Na2O       0.05
CaO        0.78
MgO        0.01

Al2O3      0.46

SiO2       2.1
TiO2       0.15

molecular percent Silica 56.6%



Inlay Glaze

Empirical Formula iron_Alex_1_1:

K2O        0.09
Na2O       0.26
Li2O       0.09
CaO        0.45
MgO        0.11

Al2O3      0.51
Fe2O3      0.15

SiO2       2.9
P2O5       0.02

molecular percent Silica 63.4%



Remarks

The original inlay, as placed in the kiln, was a simple ovoid about 3/8th of an inch thick. The large streaked
and textured, nearly filled-in balls are entirely the result of the interaction between the matrix glaze and inlay glaze.

The matrix glaze here, brightMatte_MSn, has significantly lower silica and higher calcium than iron_Alex_1_1.
Both glazes have low viscosity, are very fluid, and the large difference in composition leads to high cross diffusion
between the two glazes.

As is seen above in the image of the inlay glaze iron_Alex_1_1, there is almost nothing left of it, neither its micro-crystals
nor its color.

The firing is sufficiently rapid, that the matrix glaze wasn't able to completely absorb the inlay glaze.

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