I have seen this brought up before here and someone will surely give you the answer. But, just wanted to say that I have used Quilters Dream cotton in various thicknesses almost exclusive for my quilts and have never noticed which side was up or down. It always works very nicely. I love the feel of it and how it feels after quilting, too. For my current quilt I am useing QD wool for the first time and I like it, too. So my point is I don't think you can go wrong with it.