High Sodium Glazes fired at cone 10 and cone 7
Two glazes fired at cone 10 and cone 7.
In replacing Lithium Oxide, with the mole equvalent of Sodium Oxide,
many glazes had pinholes and unhealed blisters.
Here are two glazes, extreme examples, exhibiting patches of bubble froth.
Their appearance suggested that
Here I show the result of two glazes, fired to cone 10 and cone 7. At cone 10,
the bubble froth is seen. At cone 7,
bowl is ~ 4 inches in diameter, Tile is 4 inches across.
bowl is ~ 4 inches in diameter, Tile is 4 inches across.
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 4 hr hold at 1750 deg F
25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F
150 deg F an hour to 200 deg F
400 deg F an hour to 1949 deg F
120 deg F an hour to 2170 deg F with a hold of 30 minutes at 2170 deg F
300 deg F an hour to 1850 deg F then a half hour hold at 1850 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 0.16
Al2O3 0.60
SiO2 3.2
molecular percent Silica 63.63%
K2O 0.13
Al2O3 0.63
SiO2 3.15
molecular percent Silica 62.1%
some part of the glaze might have boiled.
That peaked my curiosity, and I wondered at what cone the glaze
started to
melt.
there are neither pitting nor bubbles.
Image of the glaze hiAl_4Z_3MLi at cone 10 and cone 7
fired at cone 10
fired at cone 7
Image of the glaze hiAlk_Z3K_0PSi
fired at cone 10
fired at cone 7
oxidation firing to cone 10 and cone 7 in an electric kiln
Firing profiles
Up Fire profile cone 10
Down Fire Profile cone 10
Up Fire profile cone 7
Down Fire Profile cone 7
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Empirical Formula hiAl_4_3MLi:
Na2O 0.60
CaO 0.05
MgO 0.10
BaO 0.09
P2O5 0.07
TiO2 0.18
Empirical Formula hiAlk_Z3K_0PSi :
Na2O 0.82
CaO 0.03
MgO 0.02
P2O5 0.11
TiO2 0.18