Glaze Interactions
This is a further exploration of a firing which has a slow up-fire in
addition to having the usual holds
The matrix is a variegated saturated iron glaze, the two inlay glazes are
variants of David Woof's
What are those crystals? malayaite, a tin-silicate crystal has been
found in chrome tin glazes,
The matrix (i.e., background) glaze and inlay glaze overlap minimally before
firing. The width of the
The background glaze is hiAlk_satIron_Z4J; the inlay design is
glazed with oribe-woof-PAlkAl-PSiMg
The design is created by adhering a mask and then applying the main
glaze. After drying,
The close-up images were heavily edited to enhance detail. The colors of the
full image of the bowl
150 deg F an hour to 250 deg F
300 deg F an hour to 2050 deg F
210 deg F an hour to 2210 deg F then a 1 hr hold at 2210 deg F
90 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F
300 deg F an hour to 1850 deg F then a 2 hr hold at 1850 deg F
300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F
300 deg F an hour to 1700 deg F then a 3 hr hold at 1700 deg F
25 deg F an hour to 1650 deg F then a 1 hr hold at 1650 deg F
K2O 0.20
Al2O3 0.64
SiO2 3.77
molecular percent Silica 65.7%
Added:
5.0% Copper Oxide
K2O 0.17
Al2O3 0.35
SiO2 3.3
molecular percent Silica 70.68%
Added:
5.0% Copper Oxide
K2O 0.13
Al2O3 0.35
SiO2 2.73
molecular percent Silica 63.84%
Added:
0.4% Chrome Oxide
This firing features a 'rounded at the top' firing profile; with a hold
of an hour 100 degreesF
on the way down.
oribe glaze, one of which contains chrome, Tin
and rutile. The fascination is the occurrence of white crystals
in the
interaction region between the chrome bearing glaze and the matrix glaze. No
such crystals
are visible between the copper bearing glaze and either of
the other glazes, the chrome glaze or
the matrix glaze.
might the malayaite have lost its chrome in the
interaction region with the matrix glaze? Wollastonite crystals
likewise have
been found in chrome tin glazes - has that migrated into the interaction zone
and been
left behind by the departing waves, so to speak?
original inlay, which varied from an eighth of
an inch to three quarters of an inch, is considerably thicker than my
usual inlay.
and oribe-woof-PAl-Cr-0.
the mask is removed and the open area filled in with a
second glaze, using a bulb syringe
with a needle applicator.
are as they appear in bright light.
Close up Images of the interaction region
Image of the piece
bowl with glaze hiAlk_satiron_Z4J
and inlay glazes oribe-woof-PAl-Cr-0
and oribe-woof-PAlkAl-PSiMg
bowl is ~6 inches in diameter
oxidation firing to almost cone 11 in an electric kiln
Firing profiles
Up Fire profile hot cone 10
Down Fire Profile hot cone 10
Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.
glaze composition
Empirical Formula hiAlk_satIron_Z4J :
Na2O 0.47
CaO 0.31
MgO 0.02
Fe2O3 0.10
P2O5 0.07
TiO2 0.15
Inlay Glazes:
Empirical Formula oribe-woof-PAlkAl-PSiMg:
Na2O 0.05
CaO 0.49
MgO 0.29
P2O5 0.01
Empirical Formula oribe-woof-PAl-Cr-0 :
Na2O 0.04
CaO 0.82
MgO 0.01
TiO2 0.12
SnO2 0.06
Remarks
below top temperature, and a slow climb from there to
the top temperature.