Colourfastness
Dry passes and wet fails is not a dye problem — it is a washing-off problem. The gap between the two grades says which one you have.
— grades
The tighter of the dry and wet margins
A negative margin is a failure against the buyer specification. Grey scale grading is visual and observer-dependent, so a mean sitting within half a grade of the minimum should be re-read by a second assessor under standard illumination before the lot is dispositioned. A dry-to-wet gap beyond about one grade points at soaping and washing-off rather than at the dye.
Crocking (Rubbing) Colourfastness Assessment — free, with the formula and a worked example, at Textile School.