I always prewash and have had some shrinkage that is amazing. I lost 4" on the width of a red solid. For this reason, I always purchase at least 1/4 yd more than I need or up to a yard for a 3 to 4 yd length or more. Have also had bleeding problems with LQS quality fabrics. I purchased a beautiful blue Patrick Lose Moda marble that has been washed several times and still bleeds. I guess it is time to give up on it. I always prewash due to the shrinkage and bleeding issues I have come across.