Polyester knit fabrics contain man-made fibers that provide comfortable stretch. When you wear clothing made of polyester knits, you can enjoy the combination of comfort and style. Keep in mind, as you hem polyester knit fabric, it has some degree of stretch incorporated into the fibers. When you hem this material properly, it should stay neat and attractive.
Sew a zigzag stitch or an overlock stitch along the raw edge of the knit fabric to finish the fabric edge and prevent it from stretching and fraying.
Place the item on a hanger and allow it to hang vertically for 24 hours. Hanging will allow the knit fibers to stretch out slightly before hemming, ensuring that you hem the item at the proper length.
Determine the proper length of the hem. Try the item on, if possible, and ask an assistant to help you mark the hemline. Measure up from the floor with the ruler to the point on the fabric where you want the hem, and place a mark at this point with the fabric pen. Make similar marks along the entire hemline with the ruler and fabric pen.
Iron the fabric under with the iron and pin it in place with the pins.
Insert a twin needle into the sewing machine and thread the needles with standard thread according to the configuration of the sewing machine. Wind the bobbin with the textured nylon thread and insert the bobbin into the machine. Set the stitch length to 3.0 or 3.5 stitches per inch.
Place the knit fabric into the sewing machine, positioning it to sew the double row of topstitching, 1/2 to 5/8 inch away from the hemmed edge.
Stitch slowly and carefully along the hemline, taking care not to stretch the fabric as you sew the hem.
Remove the pins to finish hemming the polyester knit.