I used to pre-wash.Then my fabric addiction grew immensely.I do not pre wash anything anymore.If I had to prewash it all -I would not have a life anymore.I have tested some dark colors and batiks in the sink in hot water-all has been fine.I have made and used many quilts-with grandkids,dogs ,etc-never ever had a problem yet.I just think I have to many quilts to make and less laundry is great.