The effect of lithium on a local reduction Celedon glaze
Replacing the lithium in a celedon glaze with K2O + Na2O transforms a greenish
grey celedon glaze to an aqua celedon.
The second glaze has the same mole fraction of alkali metals as the first, the
lithium oxide has been replace by K2O + Na2O.
glaze.
The glaze containing lithium
A translucent pale grey-green glaze, full gloss, the translucent results from
small bubbles traped beneatht the glaze surface.
glaze with no lithium.
A translucent pale aqua glaze, full gloss, the translucent results from
small bubbles traped beneatht the glaze surface.
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 .11
Al2O3 .4
SiO2 3.82
molecular percent Silica 72.8%
glaze has 0.2% silicon carbide added for local reduction of iron.
K2O .18
Al2O3 .4
SiO2 3.82
molecular percent Silica 73%
glaze has 0.2% silicon carbide added for local reduction of iron.
The glaze celedon_PA_Z2D also has slightly less Fe2O3 than glaze celedon_PA_0,
did that deficit in iron contribute to the change in color?
Glaze celedon_PA_0
bowl is ~4 inches in diameter
Glaze celedon_PA_Z2D
bowl is ~4 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 celedon_PA_0 :
Na2O .15
Li2O .1
CaO .49
MgO .06
ZnO .09
Fe2O3 .02
Empirical Formula Glaze celedon_PA_Z2D
Na2O .18
CaO .49
MgO .06
ZnO .09
Fe2O3 .013
TiO2
Remarks