I've got a request for a blue/blue green glaze for a cone 6 cassarole. I'm thinking of using Frogpond's sapphire blie but changing the colorants to about 3/4%cobalt carb and about 1 or 2 % copper carb instead of the 1.5% cobalt carb and the 4% rutile.
The glaze I'm trying to match is a clear dark bluebreaking to green blue.
I'm hoping someone her has testes different colorants in this base.
Please let me know some thoughts on this, if you can.