Like the others who have replied here, I do not wash my quilt tops until quilted and bound, but I will soak some pieces or fabrics in hot water to shrink them. Roll the pieces in a towel to absorb excess water and then lay flat to dry. That way, the fabric will shrink but not fray since you are not agitating it in the washer. The fabrics will be pretty flat and won't need to be ironed if you roll them carefully. Good luck.