It's no small feat.
The learning curve on just dealing with the clay body was a nightmare, but once that was figured out(ish), finding a glaze that would play well with this clay was even worse. Aardvark was up front and honest when I asked them about glazes that would work. They flatly stated that the blistering and pitting problems are a plague with this body. They did have a few in-house glazes that they could recommend, but other than that, they were receptive to any findings.
Personally, I like this lead.
It's from an archived post from 2011 by Aaron Britton.
All I can say up front is that it really works.
This glaze is different. It runs cone 4 to allegedly cone 14.
I'm going to let Aaron do the speaking on this one and have him give you the recipe.
"The liner glaze is a PB (Plastic Bitrox) Liner. This glaze works very well with this clay because the PB Liner is able to be fired with a range of cone 4 to cone 14. So if the cassius Basaltic clay still has gasses to be released, even after a longer bisque period, the PB Liner stays in a liquid / molten state for a longer time, giving the gasses from the clay time to escape without creating cratering in the glazing.
The PB Liner recipe with Percentage by Weight:
Colemanite (Gerstley Borate) 50%
Plastic Bitrox 50%
To fill a 5 gallon bucket only 3 quarters full you would use
Colemanite (Gerstley Borate) 3000 grams
Plastic Bitrox 3000 grams
Zircopax 600 grams"