I learned to always wash them. Although most don't bleed there are those that do, most don't shrink but there are those that do, and batting? Well it IS going to shrink! You can use a color catcher (which is a wise idea), always need a sharp needle and sharp rotary cutters, and don't forget 1/4" seams. Sometimes the shrinkage is in the seams and not in the fabric. Any fabrics bought at second hand shops or at garage sale wash, wash, wash. Hope this helps. Everyone here has great ideas.