Reactions at the interface between two glazes
The interaction at 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_Z2H_0PSi; the foreground design is
glazed with iron_8_R_C10_13PSi.
The background glaze is grey in an oxidation firing as it contains silicon
carbide as a local reducing agent.
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 0.14
Al2O3 0.54
SiO2 3.41
molecular percent Silica 68.6%
0.02% Silicon Carbide added
K2O 0.11
Al2O3 0.56
SiO2 3.12
molecular percent Silica 63%
The background glaze and inlay glaze are from disparate regions in the land of
glaze. The background glaze is high in alkaline earths,
The high viscosity of the background glazes is a consequence of the
combination of low alkali metals with
Both the alkali metals and iron have diffused from the inlay glaze into the
background glaze, but at different rates.
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 longquan_n_song_Z2H_0PSi and inlay iron_8_R_C10_13PSi
bowl is ~6.5 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_Z2H_0PSi :
Na2O 0.07
CaO 0.58
MgO 0.12
ZnO 0.09
Fe2O3 0.02
Inlay Glaze
iron_8_R_C10_13PSi :
Na2O 0.45
Li2O 0.25
CaO 0.17
MgO 0.02
Fe2O3 0.28
Remarks
particularly
calcia; the inlay glaze is a saturated iron glaze high in Alkali metals.
The background glaze is nearly a clear celadon, but it contains more
alumina and less alkali metals than
a clear celadon glaze.
relatively high alumina.
That difference in the rate of
flow of the alkalies and iron has generated a range of compositions in the
interaction zone, creating the range of
colors and textures seen here.