Sewing elastic can be tricky, but a few tips can help. Many different kinds of elastics are available for use in all types of garments. Two ways elastic can be applied to a garment are in a casing or by direct application to the seam allowance. Stretching the elastic first will ensure it bounces back after sewing. A ballpoint needle is best for sewing elastic.
Packaged elastics will say on the wrapping what they are best suited for. There are sturdy elastics for waistbands and thinner, softer ones made for pajamas and baby clothes. They range in width from 1/8 inch (3.18 mm) to two inches (5.08 cm) or more. Clear elastic is made of polyurethane rather than rubber and can be used for people who have latex allergies. It isn't visible and is much thinner than regular elastic.
Accurate measurement is important because sewing elastic to fabric will make it stretch. The elastic should be stretched a few times before sewing to allow it to “warm up” and be certain it retains its recovery properties. It’s a good idea to test it this way before buying if possible. A length of roughly ten percent less than the actual measurement will allow for this during sewing if the elastic is to be applied directly to the fabric.
A zigzag stitch and a longer stitch length should be used when sewing elastic. Fashioning a sleeve or leg opening is easier if the elastic is made into a circle first. Overlapping the ends will make a lump in that spot. The best way to fasten them is to butt them together and zigzag stitch over the seam a few times. The elastic can then be pinned at quarterly intervals to the seam allowance and sewn onto it using the zigzag stitch.
Once the elastic is fastened to the seam allowance, it can be turned under and the bottom edge sewn shut to finish it. If sewing elastic directly to the fabric, a ballpoint needle is a good choice. This particular needle has a blunt edge that won’t catch or cut threads in knits or elastic.
Making a casing in the fabric instead of sewing elastic directly to it allows for easy adjustment later, as in the case of a waistband. A good tip for threading elastic through a casing is to use a safety pin on one end and push it through. The ends can then be sewn together and the opening in the casing closed. When using this method, the elastic measurement can be a bit longer to allow for comfort.
