I wash my coored fabrics... not white on white for example. I just bought some red and blue fabric to finish out my red/white/blue pinwheel quilt. Washed the red and blue... blue was fine. Had to use almosta whole box or Shout Color Catchers to clean up the red. Wow! Red does not always run but this cloth was a marathon. Think I have it clean and ready to add to my quilt. I pick and choose what I prewash. I would have been devastated if I had not washed the red.