With most batiks, you can use either. Before you use your fabric, look closely at both sides, fold one side up against the other and see if you can see any significant difference. If you can't, just go ahead and use the fabric and not worry about it. If you can see a difference, and want to definitely use one side only, then do something to mark on the back side of the pieces so you will be using the side you want for the right side of the quilt.