iron colors in firings with several holds
The glaze, wisskirchen-crystals-PAl in simplified firings is
Those firings has holds only at the temperatures 1650 degF and 1900 degF.
Here we elaborate on
This is a continued exploration of the effect of holds in the down-fire of a
saturated iron glaze. All of
I wish to see the effects of two down-fire holds, and in particular
explore the effect of
I fired this glaze, wisskirchen-crystals-PAl in four distinct firings. All
four firings have the same
Firing 1:
In the down-fire, there is one four hour hold at 1900 degF, followed by a four
hour hold at 1650 degF.
Firing 2:
In the down-fire, there is one four hour hold at 1650 degF, followed by a
four hour hold at 1900 degF.
Firing 3:
In the down-fire, there is one four hour hold at 1650 degF, followed by a four
hour hold at 1900 degF,
Firing 4:
In the down-fire, there is one eight hour hold at 1650 degF followed by a four
hour hold at 1900 degF.
The down-fire of Firing 2 reverses the order of the holds of the down-fire of
firing 1. Likewise the
Firings 1 and 2 are a pair of firings which differ only in the order of the
down-fire holds. Likewise
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
300 deg F an hour to 1900 deg F then a 4 hour hold at 1900 deg F
300 deg F an hour to 1650 deg F then a 4 hour 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 hour hold at 1650 deg F
400 deg F an hour to 1900 deg F then a 4 hour 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 hour hold at 1650 deg F
400 deg F an hour to 1900 deg F then a 4 hour hold at 1900 deg F
300 deg F an hour to 1650 deg F then a 4 hour 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 an 8 hour hold at 1650 deg F
400 deg F an hour to 1900 deg F then a 4 hour hold at 1900 deg F
K2O 0.10
Al2O3 0.55
SiO2 3.45
molecular percent Silica 64.6%
These are some of the additional firings with distinct down-fire protocols,
and distinct results,
Comparing wisskirchen-crystals-PAl in firing 2 to firing 1:
There is a greater degree of intermixing of dark and light colored markings,
and a greater preponderance of
comparing wisskirchen-crystals-PAl in firing 4 to firing 3:
Markings resembling dendritic growths are seen on the outside of the firing 4
bowl, and the surface
shown here .
those firings by including both of those holds in
various orders in each of these firings.
the down-fire holds in these firings are at
either 1650 deg F, or at 1900 deg F. These firings however
will have a hold
at both of these temperatures.
interchanging the order of the holds.
up-fire protocol.
followed by a four hour hold at 1650 degF.
Firing 7 has all of the hold time at 1650 degF
preceding the hold at 1900 degF.
Firing 6 and Firing 7. I ask if the order of
the holds is relevant or only the time in the holds?
The answer for this
glaze seems to be yes.
Image of the glaze wisskirchen-crystals-PAl in Firing 1
Image of the glaze wisskirchen-crystals-PAl in Firing 2
Image of the glaze wisskirchen-crystals-PAl in Firing 3
Image of the glaze wisskirchen-crystals-PAl 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 wisskirchen-crystals-PAl:
Na2O 0.24
CaO 0.62
MgO 0.04
Fe2O3 0.31
TiO2 0.03
Remarks
to which I aluded in my prior note.
dark markings. In the inside of the firing
2 bowl there are matte yellow clusters in a dark glassy matrix,
which are not
seen in firing 1.
of the outside has a waxy near gloss, all in contrast to
that seen in Firing 3. Additionally, the matte yellow
clusters in the dark
glassy matrix as seen in Firing 2 are seen here.