Hobbs 80/20 stiffness ....about a 10 inch square sandwich will stay flat in your hand and not bend kind of like corrugated cardboard but you can easily bend or fold it with 2 hands. You can peel up the top or bottom and re-fuse if you get a wrinkle. I do not use steam to iron since the fusible is water solvable. If you are using another brand then I can't give you any pointers. I have no trouble machine quilting through the Hobbs.