I hand wash the fabrics now to get the sizing out, then rinse and wash again in a vinegar water mix, rinse it again, put it though the salad spinner and then heat set in the dryer. I notice the dark and red colors are the most susceptible to bleeding, though have started the process with every bit of fabric. I note also that there is a heck of a lot less fraying when done by hand.
Picked up a couple more yards this morning to practice the paper piecing with. I want to see how batik will hold up against regular cottons when done this way, though imagine there will be little problem on that score.