here are a couple of glaze tests I ran the other day fired to cone 05 on a stoneware body.
the ramp held at 1150F for 30 min then to 1700F at 500/hr then to shutoff at 125/hr to cone 05 with a kiln sitter.
Sample tiles have a black line drawn on the bisque ware and on top of the glaze to show slump and transparency. Glaze is brushed on with a second coat on the left side. I added talc to the standard "Jacky" glaze formula to get a little more hide and matte. The G20805 is not modified.
Flecks in the glaze are unmixed pigments, since I just mixed them into the base mix and did not attempt to completely blend
Jacky Mod 4
Gerstley borate 27.58
Nepheline syenite 10.84
Lithium carbonate 9.51
G2805 Cone 04-06 Matte
Frit 3134 44