50 Frit 3110
25 Zinc
25 Silica
2 Red iron
2 Cobalt
Glaze was poured and is fairly thick and glossy glass near the bottom but started to bubble with thinner application, so desired effect might change with different application. The top picture was a range of different frits used with the same silica zinc ratio. I found frit 3110 to respond the best with no blistering or pin-holing. Cobalt comes out dark blue at 2% cobalt and crystals formed are a light blue. This was never applied to a larger surface so I would imagine with the larger surface more crystals would form.