Gail Nichols was a visiting artist at the Utah State ceramics program for about two months while she was in the united states.  During that time, Reilly studied with Nichols.  Nichols stayed in Logan for about 2 months, during which Reilly assisted in approximately 10 firings.  This firing process, using dry soda material and whiting, is outlined in her canonical book and it seems like she didnt deviate from the process much.  The critical thing with atmospheric firing like this and good surfaces is really the clay body used, which requires a lot of experimentation and Nichols was secretive about.

ALWAYS WEAR EYE PROTECTION WHEN WORKING NEAR KILNS AND WTH DRY MATERIAL.  WEAR NITRILE OR SIMILAR HEAVY DUTY GLOVES.  SODA ASH IS CAUSTIC.
Dry Mix for 11-ish pound batch (5-ish pound dry weight 
1500 g whiting
1000 g baking soda
1000 g soda ash
Mix dry then add 1800 g water.
Stir rapidly for about 60 seconds and the mix should setup rapidly.  Feels like plaster.
For cone6 add 200 g borax to the dry mix before adding water.