I read on here that you can even prewash jellyrolls by hand then spin them out using a salad spinner a few at a time. I'm going to try it on a jelly roll sometime in June. I would definitely prewash the batiks in straight hot water and Retayne checking for colorfastness with a color catcher. Another post suggested putting the color catcher in a mesh bag so it can't clog up washer. Especially in front loader. Have fun with your project.