Multiple Shifting Edges
A descendant of the glazes seen
here and
here is shown.
The glaze featured in this note, iron_Alex_2, is derived from iron_Alex_0 and
iron_Alex_1. In its empirical formula,
Images of all three glazes are shown below;
The alkali metal: alkaline earth ratios of these glazes:
iron_Alex_0 1.46
iron_Alex_1 1.06
iron_Alex_2 1.29
The alkali metal:alkaline earth ratio of iron_Alex_1 is 1.06, lower
than the 1.46, and 1.29 respectively
The glazes iron_Alex_2 and iron_Alex_0 both feature large acyclic
micro-crystals in a full gloss matrix,
iron_Alex_2 has lower alkali metal:alkaline earth ratio than
iron_Alex_0, but also lower alumina,
iron_Alex_2 has alumina matching that of iron_Alex_1, and total alkali metals
closer to that of iron_Alex_0,
bowl is ~ 3.5 inches in diameter.
bowl is ~ 3.5 inches in diameter.
bowl is ~ 3.5 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 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 0.10
Al2O3 0.53
SiO2 2.96
molecular percent Silica 63.6%
K2O 0.08
Al2O3 0.57
SiO2 3.0
molecular percent Silica 63%
K2O 0.07
Al2O3 0.53
SiO2 2.97
molecular percent Silica 63.5%
it has the higher alkali metals
of iron_Alex_0, and the lower Alumina of iron_Alex_1.
of iron_Alex_0 and iron_Alex_2.
but iron_Alex_2 has fewer of the
copper-colored teensy crystals and the background color shifts from
midnight
black to beer-bottle brown. This can be attributed to the lower alkali content
of iron_Alex_2.
and is a bit more viscous, so more of it
remains higher up on the pot wall.
so that in this case the high alkali metal,
rather than high alumina determines the nature of the glaze.
Image of the glaze iron_Alex_2
inside
outside
Images of ancestors
Image of the glaze iron_Alex_0
inside
outside
Image of the glaze iron_Alex_1
inside
outside
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
Empirical Formula iron_Alex_2
Na2O 0.32
Li2O 0.14
CaO 0.34
MgO 0.10
Fe2O3 0.15
P2O5 0.02
Empirical Formula iron_Alex_0
Na2O 0.37
Li2O 0.14
CaO 0.32
MgO 0.09
Fe2O3 0.15
P2O5 0.03
Empirical Formula iron_Alex_1
Na2O 0.33
Li2O 0.12
CaO 0.38
MgO 0.10
Fe2O3 0.15
P2O5 0.02