You noted in your response to the poster to use Retayne ....This is not the course of action for any item that has been constructed . Retayne should only be used prior to construction/cutting and used to set the dyes. Sythropol is the recommened method once a item has been completed and the option to pretreat and set the dyes is past.
Using Retayne once an item is completed will work to set the running dyes that have migrated to other fabrics.