I never pre-wash my fabric. I like to sew on it while it still has some body and I like the look after it is washed as it puckers some. If I am concernd about colors running I put in a color catcher sheet for the first wash. You can find these in the detergent section of the grocery store. If you do have a quilt that runs, you can still save it by washing it with color remover that is sold with the fabric dies.