Cobalt colors at cone 6
Glazes are fired at cone 6 in an electric kiln.
The kiln is cooled slowly, at a rate of 25 deg F an hour in the temperature interval 1750 deg F to 1650 deg F, with a 1 hour hold at 1650 deg F.
We consider two families of glazes containing 1 % cobalt. These two families are #1 Family: zinc_181_n, n = 0, 1, 2 and #2 Family zincSr_181_n, n= 0, 1, 2.
The glazes in both families contain substantial MgO, and minimal CaO.
The glazes in the first family have moderately high alkali metals and zinc_181_0 contains BaO in addition to ZnO and SrO.
The glazes in the second family, have uniformly higher alumina, and lower silica alumina ratio.
The dark/light coloring of the leaves is the result of utilization of distinct leaf washes on the two halves of the leaf as divided longitudinally.
One side of each leaf has redart clay wash, the other a wash consisting of a thinned feldspathic glaze, which is nearly 80 % feldspar.
The dark edge at the upper rim of several bowls is the result of downward flow of the pots outside glaze into the inside of the pot.
The zinc_181_n, n = 0,1,2 family of glazes
glaze zinc_181_0 on a bowl diameter ~4 inches
glaze zinc_181_1 on a bowl diameter ~4 inches
glaze zinc_181_2 on a bowl diameter ~4 inches
The zincSr_181_n, n = 0,1,2 family of glazes
glaze zincSr_181_0 on bowl ~4 inch diameter
glaze zincSr_181_1 on a bowl ~4 inch diameter
glaze zincSr_181_2 ~4 inch diameter