Lingerie elastics are much softer and smoother than regular elastics and often have a decorative edge. When attaching them using a serger to a fabric meant to be worn as lingerie, you create the effect of a lacy decorative seam. A serger is a device similar to a sewing machine that uses loopers instead of bobbins together with needles to stitch, cut and overlock a seam. To serge lingerie elastic, use an elastic foot attachment.
Set the serger to a three-thread overlock stitch program, or if available, a four-thread ultra-stretch mock safety stitch program. Depending on what type of serging or overlock machine you have, you may have different settings to adjust.
Set the stitch length to four millimetres, or in some machines, five millimetres. Set the stitch width to the width of your elastic.
Put the setting for the upper knife of the serger at "Engaged."
Place the tension settings of the serger at "Normal" or "Standard."
Snap on the elastic foot. For some machines, insert the left or right needle, depending on the width of the elastic and stitch type. Thread the machine.
Loosen the tension control screw on top of the elastic foot to open the front of the foot.
Insert the elastic into the foot, through the slot and under the foot, until it reaches the needles.
Sew the elastic for one inch or more to be sure the elastic is being caught. Tighten the tension control screw to stretch the elastic.
Insert the fabric under the foot and sew it together with the elastic. The fabric seam should face to your right. If your elastic has a lacy edge, that should be on the left. Adjust the tension control screw to the right for a tighter stretch and to the left for a looser stretch.
Finish the seam by slightly folding over the fabric edge with the sewn-on elastic to the left, and topstitching along the right fabric side. Your lacy edge should extend past the fabric edge and the finishing seam should not be visible. Use an elastic needle if your machine has this option.