Also called an "appliqué stitch," a fell (or "felling") stitch is used to appliqué one layer of fabric (generally a folded or selvage edge) to another. It's quick, strong, and flexible-the piece sewn on with a fell stitch can move somewhat like a hinge, and that makes it good for installing linings. It is also used to sew lace-either as appliqués or appliqué seams. The fell stitch is seen in millinery work as well as clothing; it is used to attach hat bodies to brims and to attach hatbands to hats. The stitches themselves typically sit 90 degrees to the edge, or they can be angled slightly.
1. Emerge on the folded edge. The stitch should be about 1mm away from the fold.
2. Insert the needle directly into the fabric next to the fold. Run it diagonally so that it emerges beyond the first stitch.
3. Pull the stitch closed. See how the stitch sits 90 degrees to the fold? Sew the stitches between 1⁄8 to 1⁄4 inch apart.
Except from Threads, Issue 135, p. 65.