a green micro-crystalline glaze
With no downfire holds, the glaze wisskirchen-crystals-PPAl-PSi, the subject
of this note, and
The way a glaze appears after a standard firing without downfire holds can be
significantly different
We show wisskirchen-crystals-PPAl-PSi in two firings.
In the first firing, with no downfire holds, we see a glossy mottled brown black
glaze with a light
The glaze wisskirchen-crystals-PPAl-PSi has higher silica:alumina ratio than
the glaze seen in the
A separate glaze, the glaze wisskirchen-crystals-PPAl has lower silica, and in
a different firing, it is
The bowls are ~4 inches in diameter.
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 min at 2310 deg F
Turn Kiln Off
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 min at 2310 deg F
300 deg F an hour to 1850 degF with a hold of 2 hours at 1850 degF
300 deg F an hour to 1750 degF with a hold of 1 hours at 1750 degF
300 deg F an hour to 1700 degF with a hold of 3 hours at 1700 degF
25 deg F an hour to 1650 degF with a hold of 1 hours at 1650 degF
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 min at 2310 deg F
300 deg F an hour to 1650 degF with a hold of 3 hours at 1650 degF
400 deg F an hour to 1850 degF with a hold of 2 hours at 1850 degF
300 deg F an hour to 1750 degF with a hold of 1 hours at 1750 degF
300 deg F an hour to 1700 degF with a hold of 3 hours at 1700 degF
K2O 0.11
Al2O3 0.61
SiO2 3.90
molecular percent Silica 66.6%
K2O 0.11
Al2O3 0.61
SiO2 3.35
molecular percent Silica 63.1%
wisskirchen-crystals-PAl-Malk, the glaze shown in this
previous note, appear nearly identical.
than its appearance when holds are included in the
downfire. The crystals (if any) that might grow
in a glaze when holds are
added to the downfire are offen unpredictable.
dusting of white particles. By contrast, with holds
in the downfire, a variegated mixture of yellow,
green and brown
micro-crystals are seen, together with a spattering of dark iron spots.
previous note, which I expect is the cause of the shift
toward cooler colors.
orangey. We show this glaze under the heading
of "Firing 3.".
Image of the glaze wisskirchen-crystals-PPAl-PSi in Firing 1
Image of the glaze wisskirchen-crystals-PPAl-PSi in Firing 2
Image of the glaze wisskirchen-crystals-PPAl in Firing 3
oxidation firing to cone 10 in an electric kiln
Firing profile 1
Up Fire profile cone 10
Down Fire Profile cone 10
Firing profile 2
Up Fire profile cone 10
Down Fire Profile cone 10
Firing profile 3
Up Fire profile cone 10
Down Fire Profile cone 10
Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.
glaze compositions
Empirical Formula wisskirchen-crystals-PPAl-PSi :
Na2O 0.25
CaO 0.60
MgO 0.04
Fe2O3 0.31
TiO2 0.04
Empirical Formula wisskirchen-crystals-PPAl :
Na2O 0.24
CaO 0.61
MgO 0.04
Fe2O3 0.32
TiO2 0.04