High Alkaline Glazes
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.
Both of these glazes have bases dominated by alkali metals, and contain minimal CaO. These glazes contain a small amount of iron and rutile.
These glazes, considered as cone 6 glazes are high in alumina. The silica alumina ratio for these glazes is below 6.
glaze alk_179_2_Zn on a bowl diameter ~4.5 inches
The non-alkali metal bases in this glaze is predominantly ZnO
Commentary
This glaze is narrowly balanced between un fused and liquid like water, in a narrow window such that it matures to a full gloss glaze.
Any of several changes in composition will either prevent fusion or cause this glaze to stream off the pot as if it were water.
The full gloss of this glaze is in this case not an indication of a fluid non-viscous glaze. The high viscosity of this glaze is what allows it to take a sharp crisp leaf print.
glaze alk_179_1Li
The non-alkali metal bases in this glaze are MgO, and BaO, with MgO almost twice that of BaO
Commentary
This glaze is viable only if applied thin, the varigated colors however hold up to that restriction.