I don't prewash unless it's a dark batik (blue, red, green, etc.) I don't use a lot of batiks so this normally is not an issue for me. Also, if you prewash, the washing/drying will shrink the fabric a bit. I like the crinkled look of a washed quilt & figure that if I prewash the fabric I won't get as much of a crinkle look that I like.