Place the laundered and ironed gossamer fabric face side down over the seat back so that the edge of the fabric overlaps the chair seat by 1 inch. Pinch the front and back side of the fabric together with your fingers. Pin through both layers of fabric along the sides of the fabric at the width of the widest part of the seat back. Remove the fabric.
Trim the bottom back of the fabric even with the bottom front. Trim away from your pins 1/2 inch for seam allowances. Remove the pins. Open your piece and draw a pattern onto paper for additional covers.
Fold the fabric in half with face sides together. Sew your side seams with a 1/2-inch seam allowance. Turn the bottom edge under 1/2 inch and sew with a hem stitch. Turn the cover right side out and iron the seams.
Position the gossamer cover on the chair. Cut tulle 18 inches wide and 6 feet long. Gather the tulle and wrap it centered on the front of the chair. Pull the tulle firmly to the back and tie a bow. Reach up under the back center of the gossamer cover and safety pin the bow in position.