I would just test a small corner of each color and see if when it hits the water it bleeds. if it doesn't or it is very minimal I would go a head and run with it. if there is bleeding. I would just set them all in luke warm water in the sink with retain or synthrope. then let them air dry. this will help keep the shrinkage to a min. this is how i was all my batiks that I think will bleed. and if you are in a cold area, then let them sit outside in the cold air. it will dry them faster. well as long as the humidity is low. hope this helps.

With Batiks it is my experience that there is almost no shrinkage. I had one shrink 1/4 inch over 1 yard and I chalked it up to a measure issue with me.
But the chances of a Batik running are VERY HIGH. Pretreat with Retayne, or soak and rinse before use.

I believe it is a major fabric sin to not prewash. But I started quilting with kits and well you just can't prewash some of those small pieces. Yesterday I washed my first NON-prewashed quilt....I sat on the floor next to the washer the entire time...the buzzer went off I was sick to my stomach as I opened the door, pulled out the quilt....not a problem, it looked perfect!

Glad you asked about Batiks, I want to make a purple and yellow one but I hear horror stories about bleeding. Im mentally storing everyone tips from this thread.

I would not prewash.

I would not prewash. I would use a color catcher and wash it upon completion.

I have never had a color bleeding problem with Hoffman batiks and I have Connecting Threads batiks and none of them have color bleeding problems so far. I like the colors of the CT batiks much better then the Hoffman.

I have had huge Issues with Hoffman batiks and bleeding/running, particulary the 1895 dark colors. Nothing would stop the running until I used Retayne.

I rarely buy dark batiks so that may be why I haven't had the bleeding problem. I have used the Bali Pops but if any of the strips have bleed after being sewn and washed, they bled on to each other so I haven't noticed.

I ordered a "jelly roll" of batik strips and asked one of my quilting teachers if I should wash them. I was worried about shrinking and distortion. Here were her directions, if I felt like I had to wash them. (1) Don't wash them in the washing machine (I was thinking about putting them in a lingerie bag), (2) fill your bathtub with the hottest water you can stand, (3) lay your fabrics in the water and let soak for a short time, (4) swish around gently, (5) gently squeeze out the water, (6) flatten the fabric and place on a towel to dry.

Of course, we were talking about 2-1/2" strips, but this would probably work with 1/4 yard pieces as well.