Surprising non glaze
This non-glaze is covered in un-popped bubbles. With rather rough handling
these bubbles haven't popped. Much gas
The glaze, longquan-n-song-tsabar-Z2S, from which this glaze, ru-tsabar-Z2T-0,
is derived is semi-matte with variegated orange markings.
I'd thought to stabilize the matte texture and increase the prominence of the
markings with a moderate increase in alumina and silica.
inside of bowl:
Outside of bowl:
inside of bowl:
Outside of bowl:
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
This glaze has 0.2% silicon carbide added for local reduction.
K2O 0.19
Al2O3 0.56
SiO2 2.76
molecular percent Silica 63.6%
This glaze has 0.2% silicon carbide added for local reduction.
K2O 0.16
Al2O3 0.6
SiO2 3.12
molecular percent Silica 65.6%
Increasing both alumina and silica while maintaining a constant silica alumina
ratio is equivalent to decreasing the basic components
It's as if there are two glazes here, one which melts low and flows, and
another which when it starts to melt can't de-gass through the
must have been generated
to have produced that froth of bubbles. Where did it come from, and why are
the bubbles so strong?
If thickly
applied longquan-n-song-tsabar-Z2S is glossy, uniform and semi-opaque,
a rather insipid milky glass white.
Instead, the
result is the bubbled confection seen below.
longquan-n-song-tsabar-Z2S
ru-tsabar-Z2T-0
bowls are ~3 inches in diameter
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 glaze longquan-n-song-tsabar-Z2S :
Na2O 0.06
CaO 0.62
MgO 0.07
ZnO 0.06
Fe2O3 0.01
Empirical Formula glaze ru-tsabar-Z2T-0 :
Na2O 0.07
Li2O 0.06
CaO 0.59
MgO 0.08
ZnO 0.04
Fe2O3 0.02
Remarks
of the glaze,
those components in the first column of the seger formula. Here the silica
also is increased. The second glaze,
the one with the bubbles, has less
flux.
already
melted surface layer.