I wash any fabric that could bleed or could absorb the color that may bleed -- I have been doing this more and more and I hate the time it takes since I frequently want to use the new fabric right away. (I don't use pre-cuts, but these you don't want to pre-wash). I had a Moda fabric fade from a brilliant blue to a faded gray blue and a red RJR fabric that went to pink/orange when I washed it and I have tried to wash the intense colors ever since. I have since found that I need to wash the light colors that will be in a quilt as well, so I am trying to make sure everything gets washed first.