I don't prewash my fabrics (unless I am doing a red & white or blue & white), normally use an 80 - 20 batting. I wash all of my quilts (cold or warm water) use a color catcher and then put in the dryer like everything else. I have quilts on my beds and we have a large dog so they get washed a lot and I have never had an issue. That being said I would as others suggest look at the color catcher and go from there