Piping is an edge treatment that can turn an ordinary cushion or pillow into a designer creation. Fabric for piping is cut on the bias -- the diagonal grain -- then sewn together in a long strip. The fabric strip is folded in half and inserted into the seams of the cushion during construction to provide a crisp finishing detail. You can add cording -- small or large -- to give the piping a rounded shape, and choose a fabric that matches or contrasts with your cushion fabric. Gathering the piping is another way to make your cushion stand out from the ordinary.
Cut 2-inch-wide bias strips from your fabric. Cut enough strips to go around the edges of your cushion. Add 1/4 inch for seam allowances where the strips will be joined, plus 1/2 inch for the seams at the very ends.
Stitch the fabric strips together. Iron open the seam allowances, then fold the strip in half and iron it. At one end of the strip, fold the edge 1/2 inch toward the wrong side and iron it.
Place your cording inside the folded fabric, positioning it about 1 inch below the end fold you created. Align the edges of the fabric, wrong sides together, with the cord inside. Stitch along the right side of the fabric, next to the cord, with your zipper foot. This will hold the cord in place.
Place the piping on the right side of the cushion cover's front piece. Match the raw edges of the piping with the raw edge of the cover, or place the stitching of the piping strip on the cushion cover's seam allowance line. Secure the piping with straight pins. For a square cushion, snip into the piping fabric at each corner, up to your stitching, to help form sharp corners. For a round cushion, clip into the piping seam allowance every inch so the piping will ease around the curves.
Stitch the piping in place with your zipper foot, stopping the stitches 2 inches from the end. Trim the piping so it overlaps the opposite end by 1 inch. Remove 1 inch of the stitching from each end of the piping. Trim the cord so the ends butt together. Turn under the last 1/2 inch of the piping strip and overlap the opposite end. Secure it with pins, then stitch it in place. Finish the cushion as usual, being sure not to stitch through the piping when you join the front and back cushion covers.
You can gather the piping by stitching through the cord at one end of the folded strip, then using machine basting stitches. Pull on the threads to get the desired gathering, then attach the piping to the cushion cover as before.