No Bone Ash
A sparkly black and brown glaze, iron_8_R_Plus_SatIron_ZG, with its bone ash
removed,
Images are shown of the precursor glaze, containing bone ash, its derived glaze,
and
This is the glaze which contains Bone Ash.
The derived glaze, the glaze with bone ash omited.
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 0.18
Al2O3 0.52
SiO2 3.25
molecular percent Silica 65%
K2O 0.21
Al2O3 0.61
SiO2 3.81
molecular percent Silica 67%
The close-up pictures were taken with a digital microscope.
The tenmoku glaze satIron_Z2W_0 has intriguing markings, I imaginatively
describe them
The original glaze with bone ash shows no signs of flowing. Omitting the
bone ash removes the phosphorus,
Some flux was removed, together with some glass former. In this case it would
seem the missing glass former
Alternatively, perhaps the higher proportion of alkali metals in the
transformed glaze
turns into a drippy tenmoku glaze with interesting markings,
iron_satIron_Z2W_0.
closeups of the tenmoku surface.
Image of the precursor glaze, iron_8_R_Plus_SatIron_ZG
inside
outside
bowl is is 5 inches in diameter
Image of the glaze iron_satIron_Z2W_0
inside
outside
bowl is is 3 inches in diameter
Close-up Images of the surface of iron_satIron_Z2W_0
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_8_R_Plus_satIron_ZG :
Na2O 0.34
Li2O 0.24
CaO 0.17
MgO 0.07
Fe2O3 0.18
P2O5 0.04
Empirical Formula iron_satIron_Z2W_0 :
Na2O 0.41
Li2O 0.27
CaO 0.04
MgO 0.07
Fe2O3 0.23
Remarks
as micro-partridge feathers. The close up pictures are
included to show these markings.
a glass former, while simultaneously
reducing the base (flux) content of the glaze. This results in a glaze
with
higher alumina and silica. Nevertheless, it is more fluid.
Phosphorus is a glass former,
which stiffens the glaze.
is more important than the missing flux.
caused the greater fluidity.