Leopard Spots
Here are two glazes with leopard spots, I show close-ups of the leopard
spots on the first glaze,
The first glaze, satIron_ZG_Z3N_EPK is a bright glossy glaze with coppery
colored micro-crystals and
The second glaze, satIron_ZG_Z3N_Z4A_2, is a smooth mottled matte glaze; the
coppery colored micro-crystals
Here the leopard spots are formed by micro-crystals forming on only part
of the surface of bubbles
The second glaze has lower alkali metals, and higher calcia than the first.
It is a small difference,
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 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 hour hold at 1650 deg F
K2O 0.13
Al2O3 0.73
SiO2 3.65
molecular percent Silica 64.1%
K2O 0.12
Al2O3 0.73
SiO2 3.65
molecular percent Silica 64%
as the pot had a large distracting inlay design, and
is seen here: . The second close up has
higher magnification.
large leopard spots, black and brooding. The
gloss of the glaze is evident in the white
pin-prick spots which are
reflections off its shiny surface.
are gone, and the leopard spots are
distorted fragmented circles with bits of the matrix peeking through.
within the glaze, which when the bubbles
burst are visible as fragmented rings. These leopard spots,
while a bit
raggedy, are more dramatic.
which subtly shifts the appearance of the glaze.
close ups of the glaze satIron_ZG_Z3N_EPK
Image of the glaze satIron_ZG_Z3N_Z4A_2
inside
outside
bowl is ~3.5 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
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 satIron_ZG_Z3N_EPK :
Na2O 0.57
CaO 0.28
MgO 0.02
Fe2O3 0.24
P2O5 0.07
Empirical Formula satIron_ZG_Z3N_Z4A_2 :
Na2O 0.54
CaO 0.32
MgO 0.02
Fe2O3 0.24
P2O5 0.08