Iron Glaze with reflective surface film
A mirror-like thin film is seen on the surface of this saturated iron glaze.
This film appears to be
The mechanism for the growth of a metallic oxide micro-crystalline surface
film is likely the same as that of
The design is created by adhering a mask and then applying the main
glaze. After drying, the mask is removed
bowl is ~ 6 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 2170 deg F with a hold of 1 hour at 2170 deg F
120 deg F an hour to 2250 deg F
60 deg F an hour to 2270 deg F with a hold of 30 minutes at 2270 deg F
60 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 4 hour hold at 1750 deg F
25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F
K2O 0.20
Al2O3 0.6
SiO2 3.08
molecular percent Silica 61.2%
K2O 0.18
Al2O3 0.69
SiO2 2.28
molecular percent Silica 54.5%
composed of metallic-like micro-crystals, which
precipitate out of the glaze onto its surface.
Probably these are some
combination of magnetite and hematite as form in oil spot glazes.
the growth of micro-crystals on the
surface of matte glazes. The concentration of the second phase component
exceeds its solubility limit within the glaze melt so it precipitates and
plates out on the surface.
and the open area filled in with a
second glaze, using a bulb syringe with a needle applicator.
Image of the glaze satIron_ZT_Z3J
view of the inside of the bowl
Close up image of a section showing the reflective metallic film
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 satIron_ZT_Z3J :
Na2O 0.16
CaO 0.44
MgO 0.20
Fe2O3 0.22
P2O5 0.13
Empirical Formula inlay glaze inlay_Z3J_0 :
Na2O 0.78
CaO 0.02
MgO 0.02
Fe2O3 0.02
P2O5 0.19