iron colors in four firings
By adjusting the down-fire holds, in four firings, this low iron high calcium
glaze emerges with noticeable
All four firings have the same up-fire protocol.
Firing 1:
No holds - a baseline firing.
Firing 2:
In the down-fire, there is one four hour hold at 1900 degF.
Firing 3:
In the down-fire, there is one four hour hold at 1650 degF.
Firing 4:
In the down-fire, there is one four hour hold at 1650 degF followed by a four
hour hold at 1900 degF.
The bowls are ~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
Turn off kiln.
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 4 hr hold at 1900 deg F
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 1650 deg F then a 4 hr hold at 1650 deg F
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 1650 deg F then a 4 hr hold at 1650 deg F
400 deg F an hour to 1900 deg F then a 4 hr hold at 1900 deg F
K2O 0.07
Al2O3 0.53
SiO2 2.55
molecular percent Silica 61.5%
differences. It can appear as:
a pale yellow green glaze with iron spots
a dramaticly dark spotted pale ivory glaze
a brown spotted glaze
a pale yellow glaze with pale orange-y spots.
Image of the glaze ironYellow in Firing 1
Image of the glaze ironYellow in Firing 2
Image of the glaze ironYellow in Firing 3
Image of the glaze ironYellow in Firing 4
oxidation firing to cone 10 in an electric kiln
Firing profiles
Firing 1 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Firing 2 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Firing 3 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Firing 4 profile
Up Fire profile cone 10
Down Fire Profile cone 10
Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.
glaze composition
Empirical Formula ironYellow:
Na2O 0.11
CaO 0.81
MgO 0.01
Fe2O3 0.07