She should definately test for colorfastness on the batik strips. She can do this by wetting a q tip with water and rubbing it across the fabric and see if any colors lift off. The strips could be hand washed gently to see if any of the colors run. I wouldn't get too vigorous with them. I would keep rinsing them until the water is clear. Someone had suggested once that when she washed pre cuts she did it by hand in the sink and then put them into a salad spinner to remove the excess water.