The wax resist brushstrokes (done right after glazing) are clearly defined. This indicates that soda migration to the surface during drying is an important mechanism of the effect. Some carbon trapping is also visible on the lower section of the large bowl (and other pieces in other places in the kiln). The glaze has been applied fairly thinly so no whiter areas are visible.
Traditional Japanese high feldspar glazes having cream to orange color flashing or blushing. Potters today seek to emulate the Shino appearance using a wide range of recipes.