Glaze Reactions
The background glaze is variegated pale yellow with a salt and pepper dusting
of pale aqua, pale
The inlay, from inner to outer, is in bands of several shades of aqua,
pewter, and finally pale aqua.
A variant of this glaze has been seen previously
The glaze seen here, cooper_404_1Na_Z45_lZn, has slightly higher ZnO, lower
BaO, and lower silica than the
The inlay glaze is high in silica and alkaline earths and a full gloss. The
thin ribbon of this high silica
The matrix (i.e. background) glaze and inlay glaze do not overlap before
firing. The width of the
The background glaze is cooper_404_1Na_Z45_lZn; the inlay design is glazed with
oribe-woof-PAl-PSiMg.
The design is created by adhering a mask and then applying the main
glaze. After drying,
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 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 hour hold at 1650 deg F
K2O 0.08
Al2O3 0.41
SiO2 2.37
molecular percent Silica 62.7%
added:
1.5% nickel oxide
K2O 0.10
Al2O3 0.35
SiO2 3.29
molecular percent Silica 70.58%
Added:
5.0% Copper Oxide
yellow-brown, and white. There are larger ovoid strongly
colored aqua disks with raggedy nearly
black-aqua tinted interiors. A
slightly sparkly effect is created by an overall covering of needle shaped
zinc crystals. Where the glaze is thick in the bottom of the bowl
coffee-colored markings are visible.
The layers of aqua and metallic pewter are
interleaved. It is a most complex confection.
prior glaze. Both glazes are high in zinc
and even higher in alkali metals. A small shift in the composition
of
the bases in the empirical formula has created a large shift in the density of
the markings,
which here are distinctly more prominent. The tendency to
blister is unchanged.
inlay glaze eats into the background
glaze, creating undulating textured bands unlike anything seen
individually
in either glaze.
original inlay varied from an eighth of an inch to
three eighths of an inch.
the mask is removed and the open area filled in with a
second glaze, using a bulb syringe
with a needle applicator.
Close up Images of the interaction region
Image of the piece
bowl with glaze cooper_404_1Na_Z45_lZn and inlay glaze oribe-woof-PAl-PSiMg
bowl is ~7 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
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 cooper_404_1Na_Z45_lZn :
Na2O 0.40
CaO 0.02
MgO 0.01
BaO 0.15
ZnO 0.34
Inlay Glaze:
Empirical Formula oribe-woof-PAl-PSiMg:
Na2O 0.04
CaO 0.61
MgO 0.25
P2O5 0.01