I learned from an expert on fabric that most shrinkage occurs in the hot dryer from the POUNDING. You can't depend on the water in the washer or even a hot iron. I don't use detergent and just use the rinse cycle on gentle wash. If you cut little marks around the edge it won't fray. Different cottons shrink at different percentages so it is important to pre-wash in order to keep the fabric from shrinking after it is made into a quilt. For this reason I use Dream Green Polyester batting so it doesn't shrink. Some say it is hot. I say turn the heat down at night.