Migrating abutting 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 iron_8_R_C10_13PSi; the foreground design is glazed with paperWhite_P_celedon.
The design is created by adhering a mask and then applying the main
glaze. After drying, the entire pot is coated in wax,
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
mug with glaze iron_8_R_C10_13PSi and inlay glaze paperWhite_P_celedon
mug is ~5.5 inches high
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
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
Down Fire Profile
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
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
background Glaze
Empirical Formula iron_8_R_C10_13PSi :
K2O 0.11
Na2O 0.45
Li2O 0.25
CaO 0.17
MgO 0.02
Al2O3 0.56
Fe2O3 0.28
SiO2 3.12
molecular percent Silica 63%
Inlay glaze
Empirical Formula paperWhite_P_celedon :
K2O 0.05
Na2O 0.17
Li2O 0.19
CaO 0.06
MgO 0.05
BaO 0.24
SrO 0.24
Al2O3 0.58
SiO2 3.40
TiO2 0.15
molecular percent Silica 66%
added:
1% Cobalt Carbonate
Remarks
The background is a saturated iron glaze high in alkali metals containing CaO;
the inlay glaze contains Barium,
Strontium, Titanium, and moderate
alkali metals.
The inlay glaze is viscous,
the background glaze fluid.
Iron from the backgound flowed down into the inlay creating a range of iron
colors.
The range of colors reflects the changes in iron concentration.
Micro-crystals grew in the background glaze near the inlay, yet beyond the
iron-induced color changes. This would indicate
that other components, in
addition to iron, are moving.
Note the asymmetry in the interface between matrix below inlay, vs matrix
above inlay. The fluid matrix glaze flows
down into the inlay, the inlay
glaze moves primarily by diffusion.