I always pre-wash using color catchers. When I started quilting 3 years ago, there was much discussion about fabric, where it has been, how it traveled, how it was created, how many hands touched it (by the way I touch every piece of fabric when I am checking it out to use in a quilt and I am sure others do the same thing, how many people touched it from factory to me) soooo, I wash all my fabric, starch it and iron it before I start working on a project. I just throw it in the wash with the clothes or sheets or towels, etc usually adding 2 color catchers in a net bag and yep, almost always there is color on the color catchers from just a tad to a solid color when the wash is done. My two cents!