Glaze Thickness and Texture
A dense black second phase dominates the apprearance with a thick glaze
application.
Three faces of one glaze.
With a moderate glaze application this glaze has a dense covering of
non-metallic micro-crystals, with a dusting of metallic micro-crystals.
A thinner application produces only metallic micro-crystals.
A thick glaze application produces a dense black second phase in which a few
dense patches of micro-crystals are visible in a lustrous black sea.
With a medium application (slighly less than 1/8 inch thick), this glaze has a dense
cover of metallic micro-crystals in a dark orang-y brown matrix with small
patches
The glaze satIron_ZG_1Munge_2 is seen in the inlay decoration at the top
left. The outside is glazed with satIron_ZG_1S_1MMgP,
The pattern is created by adhering a mask and then applying the main
glaze. After drying,
Between the gunmetal lines created by fill-in of the crawl lines,
satIron_ZG_1Munge_2 is black with scattered dense bits of gold and orange.
The multitude of iron colors seen in a more moderate application are gone, as
are the dense metallic micro-crystals.
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 2300 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 .06
Al2O3 .54
SiO2 2.65
molecular percent Silica 58%
K2O .16
Al2O3 .53
SiO2 3.2
molecular percent Silica 64%
The application on the plate of satIron_ZG_1S_1Munge_2 was nearly three
sixteenth of an inch thick, more than twice that on the bowl.
This thick layer of glaze has volume, which allows vigorous movement
within the glaze, like that of boiling water.
The surface appearance and crystal formation are determined by the movement of
oxide components within the glaze.
By contrast, the thinner glaze application on the bowl has surface properties,
less movement within the glaze allows crystals to grow Glaze satIron_ZG_1S_1Munge_2
With normal application
of red and black. With a thin application, as seen on the
outside of the bowl, it has a dense cover of metallic gold micro-crystals
on a black background.
bowl is ~4 inches in diameter
A thick application and a background glaze satIron_ZG_1S_1MMgP
The inlay decoration
is framed by the interaction layer of the two glazes.
the entire pot is coated in wax, then the mask is
removed and the open area filled in with a second glaze.
plate is ~6 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Empirical Formula glaze satIron_ZG_1S_1Munge_2 :
Na2O .55
Li2O .19
CaO .19
MgO .01
Fe2O3 .22
P2O5 .17
Empirical Formula Glaze satIron_ZG_1S_1MMgP
Na2O .42
Li2O .19
CaO .21
MgO .02
Fe2O3 .2
P2O5 .05
Remarks
The altered pattern of transport
modifies the rate of crystal growth. It is this altered movement within the
glaze that makes
the black phase dominant on the plate.
after they
neucleate, giving a surface appearance with a variety of diverse crystals,
and metallic micro-crystals.