I love batiks. I generally don't prewash. But every once and a while, there will be yardage that feels stiff with dye. Dark blues, reds, hunter greens contain a lot of dye so they get prewashed. I have found that the occasional bleeder doesn't really show much. The lightest batik is usually an almond color so if it is pinker or bluer, it doesn't matter. However, if I made a batik quilt with snow white solid, I would prewash everythingl It all depends on the pattern.