I have bought FQ packs of batiks from JAF & I washed them without issue. I toss them in a sink with cold water & a Tbsp of Tide Free & swirl around a bit with my hands, then let soak with a Color Catcher for 20 minutes. Then, I rinse with clear, cool water before tossing in the dryer on low for 20 minutes, assuming they aren't still bleeding dye. I lay them on a rack to finish air drying before starching & pressing.
Like QuiltingCandy, I'm allergic to the sizing chemicals so I pre-wash everything no matter how small.