Bubble Artifacts
With a thick application, the glaze satIron_ZG_0_PK_MLi shows the remains of
bubbles that had formed in the glaze
Here, in a glaze which if fired just right, can develop oil spots, the grid
is in-your-face prominently visible.
This glaze
here , as the second pate,with the same firing protocol, had a thinner glaze
application
In the current firing It is now matte, rather than glossy as it was in the
prior firing,
An enlarged image of the bubble artifacts is shown, and a picture of the plate.
The leaf wash contains phosphorus. The leaf itself is first softened in water,
containing trisodium phosphate,
plate is ~ 8 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 1900 deg F then a 2 hour hold at 1900 deg F
300 deg F an hour to 1750 deg F then a 1 hour hold at 1750 deg F
300 deg F an hour to 1700 deg F then a 3 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 0.12
Al2O3 0.64
SiO2 3.23
molecular percent Silica 62.2%
K2O 0.43
Al2O3 0.54
SiO2 3.33
molecular percent Silica 48%
as a cellular network formed of black
leopard spots. The bubbles burst, leaving behind a crater rim of black
micro-crystals. The bubbles were sufficiently dense that they packed together
in the network seen here.
I know this glaze forms bubbles which
burst and smooth over during an extended downfire, so I'm anticipating seeing
signs of bubble action, and recognized it here when I saw it.
It's the just popped bubbles,
the relics of the craters massed together
forming this slightly irregular network that fascinated me.
that resulted in a different appearance.
and there is a substantial color shift.
which provides additional color.
Closeup Image of the bubble artifacts
glaze satIron_ZG_0_PK_MLi
Image of plate
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 composition
Empirical Formula satIron_ZG_0_PK_MLi :
Na2O 0.69
CaO 0.18
MgO 0.01
Fe2O3 0.22
P2O5 0.1
Empirical Formulae of leaf wash glaze leaf_Z3K:
Na2O 0.53
CaO 0.04
P2O5 0.15