I am with Onebyone, I wash my fabric with my regular laundry detergent. I use warm water (don't know anyone that uses hot when washing colored items anymore) and I do throw in Color Catchers if there are different colors. Since I found Color Catchers at Big Lots for $3 a box of 54 they get used a lot. Since my great-nephew is a big Star Wars fan I have made quilts and pillow cases for him and none of the fabric ran. The main reason I prewash is to remove the chemicals from the fabrics, they destroy my fingers and finger nails.