It couldn't be as simple as YB + OB in the same snake makes graphite could it (sort of like YB + Specter makes super stripe while YB + YB makes ivory)? I guess that could be disproven if Ian G's isn't a graphite (does he have a single white snake that produces both YB and OB bred to normal?). Wonder if graphite could vary on quality and show late making it even harder to figure out. But if this is another allele complex with YB, OB, specter (and whirlwind if different than specter) it might be pretty easy to predict. Maybe homozygous OB X Ivory would produce 100% graphite.