If you’ve used something that will keep the dye from running, like vinegar, you should be okay. I would do a test with a towel or something that you don’t mind ruining if it happens.
Well it turned out great. I did put a Shout Color Catcher in the pillow case and it caught all the color. (Pink. :?? I thought for sure the blue would run) But the bag looks good and my white pillow case is still white. :lol:
Before you felt the item heat set it with vinegar by soaking your item in HOT water (180-195, not quite boiling) for awhile until it is wet through. Add a glug of vinegar-~ 1/4 cup- or another type of acid (specifically acetic acid)- any vinegar or citric acid will do as will lemon juice in a pinch. Heat item in a hot water bath with the vinegar as you would to mordant for about 30-45 minutes being careful not to felt. Test colorfastness by rinsing and extracting the water in a washing machine. If after 4-5 rinses it still bleeds, mordant (heat with vinegar) again.