Intertwined glazes
The interface of adjacent glazes.
Several closeups of the interaction region of the two glazes are shown and,
for context, a picture of the pot.
The background glaze is hiAl_4Z_3, the foreground design is
glazed with mashiko_ZJ_0_N.
The design is created by adhering a mask and then applying the main
glaze. After drying, the entire pot is coated in wax,
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 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 0.16
Al2O3 0.6
SiO2 3.24
molecular percent Silica 64%
K2O 0.11
Al2O3 0.82
SiO2 5.68
molecular percent Silica 73.4%
The background glaze and inlay glaze live in different regions of the land of
glaze. The background is a high titanium glaze,
Strikingly, the background glaze is here fired a bit above its natural firing
range, which is the likely cause of its heavy crazing.
Note the rutile crystals which form surrounding the inlay. These crystals
also form at the bottom edge where the glaze ends at the foot of the pot.
These crystals nucleate, i.e get their start at a dissimilar material, much
as rock candy, sugar crystals, form on a string dipped
The inlay glaze, mashiko_ZJ_0_N was applied thickly, and by itself forms oil
spots. Here, as a result of its thick application,
then the mask is removed
and the open area filled in with a second glaze.
Close up Images of the interaction region
Image of the piece
bowl with glaze hiAl_4Z_3 and inlay mashiko_ZJ_0_N
bowl is ~8 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
Background glaze
Empirical Formula hiAl_4Z_3 :
Na2O 0.41
Li2O 0.19
CaO 0.04
MgO 0.10
SrO 0.10
TiO2 0.22
Inlay Glaze
mashiko_ZJ_0_N :
Na2O 0.11
Li2O 0.1
CaO 0.26
MgO 0.42
Fe2O3 0.23
Remarks
high in alkali metals,
containing minimal CaO; the inlay glaze is an oil spot saturated iron
glaze
low in alkali metals and high in CaO.
This glaze matures
at cone 6, and at cone 6 is a titanium blue.
in supersaturated sugar
solution.
its surface froze,
i.e. solidified while the bulk glaze beneath remained fluid. The result, was a
missmatch in dimension
between bulk and surface. The bulk finally
solidified later and at a lower temperature, so it shrank while the surface size was
fixed,
leaving the surface to pucker up as it remained attached to the
bulk material. That puckering
of the surface produced the "washboard"
look which is seen in the close-up images.