Reactions between abutting glazes
The interaction between two adjacent glazes.
Closeups of the interaction region of the two glazes are shown and,
for context, a picture of the pot.
The design is created by painting rubber latex on the bisque pot then after
the latex has cured, applying the main glaze. After drying,
150 deg F an hour to 250 deg F
400 deg F an hour to 1850 deg F
120 deg F an hour to 2130 deg F
13 deg F an hour to 2180 deg F then a two hour hold at 2180 deg F
13 deg F an hour to 2220 deg F then a three hour hold at 2220 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 .08
Al2O3 .45
SiO2 2.46
molecular percent Silica 61.8%
K2O .13
Al2O3 .71
SiO2 3.25
molecular percent Silica 65.5%
The background glaze contains Iron Oxide, the foreground or inlay glaze
contains copper carbonate.
What is it, and how did that happen?
the latex is
removed and the open area filled in with a second glaze.
Close up Images of the interaction region
Image of the piece
bowl with glaze paleGreyYellow and inlay copperYellow_Z24_0
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 paleGreyYellow :
Na2O .03
CaO .71
MgO .18
Fe2O3 .06
Inlay Glaze
Empirical Formula glaze copperYellow_Z24_0 + 1% copper carbonate :
Na2O .42
CaO .24
MgO .11
ZnO .1
Remarks
Yet the interaction of these two glazes contains a
sharply delimited opaque matte white band. The width of this band is
independant of the width of the inlay.