I have always been a prewasher but made Yellow Brick Road from FQ's. Told not to wash or they would shrink and not be enough for pattern. Then even though using black backing still told not to wash or my front would shrink differently than back when washed and pucker my quilt. OK so I obeyed only to have my black backing bleed badly when I washed the finished project even though I used color sheet. Washed twice with same results. Thankfully color sheet kept light color from top from being grayed but still those lights no longer pop with brightness they originally had and the cream colored label I made for the back turned dark gray mottled or marbled. I will definitely be prewashing from here on out no matter expect for charm squares that are precut for making purses.