Just because they're pre-cuts, don't assume they won't bleed. One of the worst bleeds I've had was with a quilt top made with jelly rolls. I washed it in cold water, small amount of orvus soap, and 3 color catchers. The darks bled into the lights, and it was unsalvageable. I was sick! I now pre-wash ALL my pre-cuts. Mainly I let them soak overnight with quilt soap and slightly warm water. Hand agitation only. I use vinegar in the rinse just to get the soap out. I know it doesn't "set" anything. If there's any color on the color catchers, I try to identify what colors, and those go back in for more washing. The rest are dried flat on a sheet outside. They are also tested for bleeding before being used (anything that came from a wash where there was bleeding is re-tested). Even after drying and pressing (not ironing), they are again tested for bleeding. I'm a fanatic about this. I work hard on my quilts, and to have one ruined by bleeding is just sickening. And I do blame the manufacturers for this. They're making cheaper fabric, and taking less care of it, so they can sell it to us cheaper, so we can spend money and time on excessive pre-washing and products like color catchers, retayne and synthrapol. I'd spend more money on the fabric if I knew it was true quality fabric, but you can get bleeding fabric from the knock off manufacturers, as well as the very best manufacturers.