First, remove any mustard remaining on the fabric using a blunt knife. Try not to rub it any deeper into the fibers. Treat the stain with a heavy-duty liquid detergent and then rinse thoroughly. Soak the garment in a dilute solution of all-fabric or oxygen bleach like OxiClean. Launder as usual in cool water. Do not dry the garment if the stain remains. Repeat the steps until stain is removed.
If the garment is dry clean only, point out and identify the stain to your professional cleaner. If you are using a home dry cleaning kit, be sure to treat the stain with the provided stain remover before putting the garment in the dryer bag.
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