Firing Effects

The glaze satIron_mashiko_neph_Imerys with three different firing protocols.

The first firing drops from top temperature to 1750 deg F at 300 deg F an hour. This rate of temperature
drop is an approximation to "dropping like a stone", yet slow enough that the multiple zones in the kiln can maintain
nearly the same temperature.

The second firing drops only to 2210 deg F at that rapid rate of 300 deg F an hour. It then has a one hour hold,
then drops to 1900 deg F at only 80 deg F an hour.

The third firing has a two-hour hold on the way up, before maturation, at 2250 deg F, 60 degrees below the
top temperature.

The primary difference between these three firings is that slowing down of the firing at a temperature
near the top, but not so high that a higher cone would thereby be reached.

The first firing has no hold, in the second firing, the hold is on the way down, and in the third,
on the way up.

I have previously noticed that glazes high in mica seem more "melted" with a hold near maturation.



Image of the glaze satIron_mashiko_neph_Imerys in Firing 1

full view

inside



full view

outside

bowl is ~ 4 inches in diameter.



Image of the glaze satIron_mashiko_neph_Imerys in Firing 2

full view

inside



full view

outside

bowl is ~ 4 inches in diameter.



Image of the glaze satIron_mashiko_neph_Imerys in Firing 3

full view

inside



full view

outside

bowl is ~ 4 inches in diameter.



oxidation firing to cone 10 in an electric kiln

Firing profile 1

Up Fire profile

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

Down Fire Profile

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



Firing profile 2

Up Fire profile

150 deg F an hour to 250 deg F

400 deg F an hour to 2050 deg F then a hold of 20 min

120 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F

Down Fire Profile

300 deg F an hour to 2210 deg F then a one hour hold at 2210 deg F

80 deg F an hour to 1900 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 Two hour hold at 1700 deg F

300 deg F an hour to 1600 deg F then a Two hour hold at 1600 deg F



Firing profile 3

Up Fire profile

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 2250 deg F then a two hour hold at 2250 deg F.

120 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F

Down Fire Profile

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



Clay body is a grolleg porcelain from Tacoma Clay Art Center.



glaze compositions

Empirical Formula satIron_mashiko_neph_Imerys :

K2O        0.08
Na2O       0.11
Li2O       0.28
CaO        0.51
MgO        0.02

Al2O3      0.61
Fe2O3      0.25

SiO2       4.0
P2O5       0.15

molecular percent Silica 66.7%



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