Alumina and Texture
First and third column components of the empirical/seger formula of these two
glazes are nearly identical, only alumina
The low alumina glaze
It is a transparent, textured full gloss glaze that is a cool pale green in
color, with sharply delimited iron brown speckles.
The high alumina glaze
It is a smooth waxy matte glaze that is a warm pale ivory in color, with fuzzy
golden brown specks. Where thick,
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 0.21
Al2O3 0.52
SiO2 2.9
molecular percent Silica 65%
glaze has 0.2% silicon carbide added for local reduction of iron.
K2O 0.21
Al2O3 0.56
SiO2 2.8
molecular percent Silica 64%
glaze has 0.2% silicon carbide added for local reduction of iron.
A speckled glossy glaze, and a satin matte glaze which differ in alumina
is substantially different.
The higher alumina glaze has a lower silica:alumina ratio.
Glaze tsabar-harris-celadon
bowl is ~3.5 inches in diameter
Glaze tsabar-celadon-PAl
it shows opaque glassy white
inclusions framed by dense dark brown iron spots.
bowl is ~3.5 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
Empirical Formula Glaze tsabar-harris-celadon
Na2O 0.07
CaO 0.65
MgO 0.01
ZnO 0.06
Fe2O3 0.01
Empirical Formula glaze tsabar-celadon-PAl :
Na2O 0.07
CaO 0.65
MgO 0.01
ZnO 0.06
Fe2O3 0.01