Glaze Reactions
The matrix glaze is derived from Emmanuel Coopers glaze 404 from his book "The
Potters Book of Glaze Recipes",
The fluid inlay glaze has diffused a substantial distance into the matrix
glaze. The result is a large
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_PMZn; 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 0.07
Al2O3 0.33
SiO2 2.47
molecular percent Silica 65%
Added:
1.5% Nickel Oxide
K2O 0.10
Al2O3 0.35
SiO2 3.29
molecular percent Silica 70.58%
Added:
5.0% Copper Oxide
The matrix glaze is high in zinc, contains barium and minimal calcia; it also
has high alkali metals for
Re The contrasting colors in the matrix glaze; the deap blue crystals are
a second phase.
In the close-ups one sees that the inlay is partitioned between two zones, a
spicular cystal zone in
The green halos surrounding the inlay sections represent the last gasp of
diffusion from the
It's all a mass road race, each zone surrounding the inlay represents a
different composition
and has undergone considerable
modification to arrive at this family of zinc matte 'calico' glazes with
strong
contrasting markings.
region of the matrix glaze framing a
remnant of the glossy inlay glaze. That frame of modified
matrix glaze
features large needle shaped micro-crystals; having a distinct composition,
and now containing
copper as well, its color also is modified.
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_PMZn and inlay oribe-woof-PAl-PSiMg
bowl is ~6 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_PMZn :
Na2O 0.27
CaO 0.04
MgO 0.01
BaO 0.22
ZnO 0.39
Inlay Glaze:
Empirical Formula oribe-woof-PAl-PSiMg:
Na2O 0.04
CaO 0.61
MgO 0.25
P2O5 0.01
Remarks
a glaze with such low alumina. The inlay
glaze is low in alkali metals, high in calcia and silica. These
two
glazes belong to distant "glaze families," so can be expected to react
strongly when laid next to
each other.
The matrix glaze is a phase separated micro-crystalline
glaze. That one phase is the deap blue
characteristic of nickel in a high
zinc glaze suggests that the zinc disproportions itself unevenly
between the
two phases. The blue phase having a much higher concentration of zinc
than the
background yellow phase.
which sharply defined needle crystals are seen, and a
glassy crazed river. That crystal zone is as it were
the beach upon which the
ocean laps. The oxides in the inlay diffuse into the matrix at varying
speeds,
the further away from the inlay, the more diverse the composition of
the migrant inlay. The glassy
river is nearly pure inlay, the spicular
crystal zone, the region into which sufficient material has migrated
to
substantially alter the chemistry of the matrix glaze. The inlay glaze being
more fluid,
this beach zone is less viscous than the matrix glaze proper,
allowing larger visible crystals
to develop.
inlay glaze into the matrix glaze.
of matrix glaze laced with some components of inlay
glaze.