Polka Dot Iron Glaze
When the bubbles in this brown glaze subsided, the brick red bottoms of the
bubbles were revealed.
It would appear that before popping, the bubbles of this glaze are laminated;
comprised of two layers of
So what is really happening here? Notice the one section on the outside of
the pot where the bubbles have
bowl is ~ 4 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 1800 deg F then a 2 hr hold at 1800 deg F
300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F
50 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 0.35
Al2O3 0.53
SiO2 3.58
molecular percent Silica 66.5%
different composition, one brick red, the other
dark brown. After popping the brick red interior is revealed.
subsided, yet the red polka dots remain.
It would take precision glazing to make that happen on a pot!
Image of the glaze jingdezhen-iron-7-13-MLi-2
inside
outside
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 jingdezhen-iron-7-13-MLi-2 :
Na2O 0.11
CaO 0.53
MgO 0.01
Fe2O3 0.12