Glaze Reactions in a Saturated Iron Glaze
The inlay glaze on its own is a translucent green glaze with no visible
micro-crystalline inclusions.
In this matrix glaze, hiAlk_satIron_P24, the inlay appears a mottled green
spiral covered in
The background glaze contains orangey-yellow micro-crystalline clusters and a
prominent glassy phase.
The sharpness of the yellow markings in an indication of the narrow
compositional range in which
The matrix (i.e., background) glaze and inlay glaze overlap minimally before
firing. The width of the
The background glaze is hiAlk_satIron_P24; the inlay design is glazed with
oribe-woof-PAlkAl-PSiMg
The design is created by adhering a mask and then applying the main
glaze. After drying,
The close-up images were heavily editied to enhance detail, colors are
brighter as a result.
150 deg F an hour to 250 deg F
300 deg F an hour to 1800 deg F
200 deg F an hour to 2050 deg F
120 deg F an hour to 2320 deg F with a hold of 25 minutes at 2320 deg F
300 deg F an hour to 1850 deg F then a 2 hr hold at 1850 deg F
300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F
300 deg F an hour to 1700 deg F then a 3 hr hold at 1700 deg F
25 deg F an hour to 1650 deg F then a 1 hr hold at 1650 deg F
K2O 0.12
Al2O3 0.62
SiO2 3.28
molecular percent Silica 63.3%
K2O 0.17
Al2O3 0.35
SiO2 3.3
molecular percent Silica 70.68%
Added:
5.0% Copper Oxide
The glaze interactions in the boundary between matrix glaze and inlay glaze
are dominated by kinetic
Copper and magnesium migrate from high concentration in the inlay
glaze, to low concentration
micro-crystalline inclusions, demarcated by a broken
bright yellow line, then shadowed in a
darker brown. The inner green
spiral isn't connected, although the original inlay masks were.
The inlay reactions with these distinct phases
are characteristically different. There are visible
flow lines from the
inlay into the matrix; at the micro-crystalline cluster boundaries, only
diffusion
of individual components is visible.
iron will provide a yellow color.
original inlay varied from an eighth of an inch to
three eighths of an inch.
the mask is removed and the open area filled in with a
second glaze, using a bulb syringe
with a needle applicator.
The colors of the bowl are as it appears in bright
light.
Close up Images of the interaction region
Image of the piece
bowl with glaze hiAlk_satIron_P24 and inlay glaze oribe-woof-PAlkAl-PSiMg
bowl is ~11 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile hot cone 10
Down Fire Profile hot cone 10
Clay body is a white stoneware from Clay Art Center in Tacoma, WA.
glaze composition
Empirical Formula hiAlk_satIron_P24 :
Na2O 0.54
CaO 0.32
MgO 0.02
Fe2O3 0.10
P2O5 0.07
TiO2 0.11
Inlay Glazes:
Empirical Formula oribe-woof-PAlkAl-PSiMg:
Na2O 0.05
CaO 0.49
MgO 0.29
P2O5 0.01
Remarks
effects, i.e., these reactions can take place only
as a result of movement of oxides between the matrix
glaze and the inlay
glaze. The various oxides move at different rates, depending on temperature.
in the matrix glaze. iron migrates in the
opposite direction from the matrix glaze into the
inlay glaze.