I wash all the yardage in cold water detergent and use a color catchers after using the pinking rotary cutter on the raw edges leaving on the selvedges (trim those after the drying) and then I press it after it comes out of the dryer (that way I know it is ready to use). I don't wash the pre-cuts but always tell the recipient of the completed quilt to wash in cold water and dry on air only or low and take it out after 10 minutes. I am not sure but in our modern day, cold water detergents to a fine job and on something as time intensive as our quilt work - cold water detergent works nicely. Also, I made the decision to purchase an HE washing machine which gently washes all our clothes much better and our clothes simply don't wear out from washing. My suggestion.