I got some older fabric from my MIL and washed it. Wish I had paid attention because the blues ran like the ocean. 9 washes later (when the quilt was done), and the water was still blue. My recommendation: Wash the stash and check along the way.
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Try something called Color Catcher. You should find it in the washing section
of your grocery store. I had to go to a bigger town to find it, mine didn't seem
to know what it was.