Is it yardage or precuts? Precuts are best washed in a mesh bag or something similar to prevent fraying. Retayne sets the dye but needs hot wash water. Definately pre-wash to see if you have any bleeders and separate into lights and darks for different loads too. I quick pre-test is to rub a damp white paper towel or cloth on the fabric and see if there is any colour transfer onto the towel/cloth.