I only prewash questionable fabric, reds, batiks, and unknowns....I use my wavy rotary blade and get next to no ravels, I also do use the delicate cycle.....and only hot water if I really question the fabric.....always dryer....if the fabric is either muslin or flannel I have been know to do this twice, but never if for a rag quilt that will be made with
all flannel....