Aventurine Glaze

Derivation

This glaze, iron_8_R_C10_2 is an unexpected result of my work on cone 10 glazes. iron_8_R_C10_2 is high in alkali metals and in particular is high in Li2O. It is as low in CaO as is possible with common ceramic materials. It has alumina of .55 and is low in silica with a silica:alumina ratio of 5. I'd several cone 6 glazes which were covered in dense metallic crystals, yet had defects which I thought the result of firing the glazes too close to the bottom of their respective firing ranges.

My first attempts to adjust these glazes to mature at cone 10, fixed the defects and eliminated the gold metallic crystals. To recover those crystals, I increased the alkali metals, decreased the CaO, increased alumina and decreased silica. I increase the alkali metals to increase mobility in the glaze, thus I hoped to increase crystal growth. The increase in alkali metals required a decrease in some other base, which I chose to be CaO. The increase in alumina was a counterbalance to a large increase in alkali metals - to prevent excessive flow in the glaze. Finally, the decrease in silica was an additional encouragement of phase separation within the glaze.

The result is a glaze that separates into two compositionally distant glazes, one of which is substantially more fluid that the other. Only a relatively small volume of the more fluid phase forms.

That small bit of very fluid glaze forms the streaks that would define a Hare's fur glaze if consistently covering the body and the beginnings of which are to be seen in this glaze.

The glaze iron_8_R_C10_2

Inside and outside of a bowl ~3 inches in diameter

detailed close up's of glaze