Yes that is the question. After cutting out some squares for a wall quilt I found some fabric that would go well for sashing. All the other fabric (batiks)were washed but the sashing fabric was not. It was a black ish fabric and I almost didn't wash it. But I am from the old school of wash all fabrics before use ...so I did AND I am so glad I did. I bled terribly. I rinsed and rinsed to get the water to run reasonably clear.
Yep, I am so glad I listened to my inner voice. Wash before using..... :)