Firing Effects
The glaze iron_Alex_0_Z38 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
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,
The third firing has a Two-hour hold on the way up, before maturation, at 2250
deg F, 60 degrees below the
The primary difference between these three firings is that slowing down of the
firing at a temperature
The first firing has no hold, in the second firing, the hold is on the way
down, and in the third,
I have previously noticed that glazes high in mica seem more "melted" with a
hold near maturation.
bowl is ~ 4 inches in diameter.
bowl is ~ 4 inches in diameter.
bowl is ~ 4 inches in diameter.
The third firing is a hot cone 10, perhaps cone 10 and a half.
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
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
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
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
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
K2O 0.09
Al2O3 0.57
SiO2 3.34
molecular percent Silica 65.3%
In the first firing iron_Alex_Z38_0 has a variegated brick red matrix with
small coppery-colored metallic crystals
In the second firing, with a hold after the peak temperature is reached, the
crystals are nearly gone. They
In the last firing, with a hold before peak temperature is reached, both the
coppery-colored crystals and the
For this glaze, slowing the firing near peak temperature, either on the way
up or down, reduces crystal formation.
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.
then drops to 1900 deg F at only 80
deg F an hour.
top temperature.
near the top, but not so high that a higher cone
would thereby be reached.
on the way up.
This is an exploration of the effect of such a
hold on glazes not containing mica. such as this one.
Image of the glaze iron_Alex_0_Z38 in Firing 1
inside
outside
Image of the glaze iron_Alex_0_Z38 in Firing 2
inside
outside
Image of the glaze iron_Alex_0_Z38 in Firing 3
inside
outside
oxidation firing to cone 10 in an electric kiln
Firing profile 1
Up Fire profile
Down Fire Profile
Firing profile 2
Up Fire profile
Down Fire Profile
Firing profile 3
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Empirical Formula iron_Alex_0_Z38 :
Na2O 0.42
Li2O 0.15
CaO 0.32
MgO 0.02
Fe2O3 0.16
P2O5 0.03
Remarks
and larger disk-shaped
translucent crystals.
are replaced by a range of swirled flows
and disks of varied iron colors.
translucent crystals are present, yet fewer,
and less dense. A dark, nearly black, phase where the glaze is thin,
has become
prominent.