With and without Mica
Two glazes, same empirical formula, sourced from different materials.
The first glaze satIron_ZG_1S_1Munge_3MMg_MLi contains 14% mica, the second
glaze
Mica seemed a convenient material as a source for potassium with little
sodium, yet I'd noticed that
I suspected the mica as the cause of its great difference from its origin, so
developed satIron_ZG_1S_Z3K,
bowl is ~ 4 inches in diameter.
bowl is ~ 4 inches in diameter.
The starting point, the original lithium bearing glaze.
This is a mug ~4.5 inches high. It has an inlay design, the orange and green oval.
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 1800 deg F then a 2 hr hold at 1800 deg F
300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F
50 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 0.24
Al2O3 0.49
SiO2 3.11
molecular percent Silica 63%
K2O 0.24
Al2O3 0.50
SiO2 3.13
molecular percent Silica 63%
The original lithium bearing glaze.
K2O 0.20
Al2O3 0.51
SiO2 2.97
molecular percent Silica 61.5%
satIron_ZG_1S_Z3K contains no mica.
mica bearing glazes would benefit
substantially from a soak near peak temperature. Replacing
LiO2 with a
combination of K2O and Na20 produced the glaze satIron_ZG_1S_1Munge_3MMg_MLi.
The original had no mica.
which has almost the same empirical formula and
no mica. The results are seen below.
Image of the glaze satIron_ZG_1S_1Munge_3MMg_MLi containing mica
inside
outside
Image of the glaze satIron_ZG_1S_Z3K without mica
inside
outside
Image of the glaze satIron_ZG_1S_1Munge_3MMg_0 containing lithium but no
mica.
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 satIron_ZG_1S_1Munge_3MMg_MLi :
Na2O 0.58
CaO 0.16
MgO 0.02
Fe2O3 0.17
P2O5 0.16
Empirical Formula satIron_ZG_1S_Z3K :
Na2O 0.59
CaO 0.16
MgO 0.01
Fe2O3 0.18
P2O5 0.16
Empirical Formula satIron_ZG_1S_1Munge_3MMg_0 :
Na2O 0.43
Li2O 0.20
CaO 0.16
MgO 0.01
Fe2O3 0.19
P2O5 0.17