Gathering may be worked by hand in running stitch or by using a long machine stitch. For a wide area of gathering, divide the edge in quarters and mark in the same way the piece to which the gathering is to be joined.
Work two rows of gathering stitches 3 mm (1/8 inch) each side of the seamline, leaving the ends loose. Repeat on each section.
Pin the edges together, matching right sides and divisions. Start to pull up the gathering threads from one end by holding the threads together and moving the fabric away from them until the gathering is tight enough to fit the opposite edge.
Arrange the gathers so they are evenly spaced across the width and secure the threads by winding a figure eight around a pin.
Baste and machine stitch along the seamline, keeping the gathered side facing up to avoid puckering.
Press carefully with the point of an iron. Pull out the gathering threads.
MAKING A FRILL
A frill is simple to make from a straight strip of fabric or from a purpose-made edging, such as broderie anglaise or lace, which needs no hem. The desired length should be 1 ½-2 times the length of the edge to which it is to be attached. Add on seam and hem allowances. If the frill is a shallow one in fine fabric, it is easier to make it in double fabric so that you do not need a hem along the outer edge. Fold the fabric double with right side out and treat the layers as one for the gathering process.
Finish by trimming the turning of the gathered edge to within 3 mm (1/8 inch) of stitching. Fold under flat edge and stitch to seamline.