I always iron my seams open.When you are working on minis the raised edge you get from pressing to the dark is so much more noticable in minis. The open seam works so much better for me. Some seams will tend to fold over but I get the majority to lay flat. I spray with sizing and iron if it doesn't. I iron the dickens out of mine. I don't press I iron it within an inch of it's life because I want it flat! I never seem to have a distortion problem at least not one I have noticed.