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 longquan_n_song_Z2S_1; the foreground design is
glazed with ru_P_tsabar_PMg.
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 0.11
Al2O3 0.44
SiO2 3.8
molecular percent Silica 72%
Added:
0.02% Cobalt Carbonate
0.2% silicon carbide for local reduction
K2O 0.15
Al2O3 0.5
SiO2 2.54
molecular percent Silica 62%
0.5% silicon carbide for local reduction
The
matrix glaze is higher in alkali metals and silica.
Silica migrates from the matrix into the inlay and very nearly absorbs the
inlay into the matrix.
Trapped bubbles beneath the surface are common in viscous glazes. The
magnification makes
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
plate with glaze glaze longquan_n_song_Z2S_1 and inlay ru_P_tsabar_PMg
plate is 10 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 longquan_n_song_Z2S_1 :
Na2O 0.13
Li2O 0.09
CaO 0.48
MgO 0.10
ZnO 0.09
Fe2O3 0.015
Inlay Glaze
Empirical Formula ru_P_tsabar_PMg :
Na2O 0.07
CaO 0.59
MgO 0.17
ZnO 0.02
Fe2O3 0.02
P2O5 0.01
Remarks
the bubbles look huge.