I seldom prewash fabrics - shocking I know - but I do prewash batiks especially if mixing them with quilting cotton weight fabrics. Washing makes the batiks a bit softer. It doesn't change the basic fact that it has a tighter weave than quilting cottons though. I find it easier to sew them and as IceBlossom recommended used a Microtex needle. And like IceBlossom, I am also a rebel when it comes to seams. I've been pressing them open for years. And have never encountered an issue by doing so. Pressing seams open does relieve some of the bulk where seam meet.