I prewash all my fabric (unless they are small pieces). When complete, the quilt goes in the washer on a regular cycle, with normal laundry soap, usually Downey, and then in the dryer. I do not iron. I make bed sized quilts to be used so there's no way I'm ironing them. Plus I like the crinkled look so I don't prewash my batting. I would only use a color catcher if I had a questionable red. Although I had a green once that I prewashed and it ran forever. I gave the quilt to it's recipient along with a box of color catchers and told them never to wash the quilt without them.