About 2 months ago I made a terra sig from local clay. It's a magnesium and iron rich bentonite. In its raw state it is purple and chocolate brown in oxidation. I don't know what it looks like in reduction yet. It melt at cone 4-5. I did triaxial blending of Gerstley borate, Nepheline syenite, and the clay with the results below. The glaze has a satin finish with two coats and semi gloss finish with one coat. It has a pleasing texture. I like the tile that has the hole in the test tube. Lemon juice test showed no discolorations. There is no crazing.
Recipe: Gerstley bborate 6.52
Neph syenite 15.22
local clay/bentonite 78.26
It was applied on bone dry clay and single -fired to reduce problems with the high bentonite and its COE. I think I have my first stable home grown base glaze.
What colorants do you think I should try next?
I have thought about adding RIO 6 - 8% to see if it will make a nice satin tenmuko that I could use as the base glase for a cone 6 oil spot or hares hair glaze. That is my aspiration.
Imput, critique, gut reactions are greatly appreciated.