The pattern on this pot was drawn with a pencil and the spots were filled in with wax resist. The salt migrated to the unwaxed areas, the matrix, and the effects of the sawdust firing went to the waxes areas after the wax had burned off in the salt firing. This is a pos/neg pattern, the matrix can be either foreground or background. This effect will only happen when you take the time to study the pot. All my pots operate this way.
Dimensions are 12.5" x 8.5"