I have found that if a fabric keeps bleeding after about 3 washes, if I let it dry then iron it, then wash again there will be no more color in the last wash. Gave this advice to BFF and saved her quilt which she was sure was ruined.
I always use very hot water and accordian fold fabric into the tub. When the water has cooled I lightly wring by hand then line dry. The very hot water takes care of shrinkage and color runs.
I've never had a problem and I wash every quilt when it is finished. Hand wash in wool mix.