Fabrics with four-way stretch are called knit fabrics, as opposed to woven fabrics which can have two-way stretch or no stretching properties at all. To maximise the stretch of a knit fabric, it is best to use a serger or overlock sewing machine, which produces stretchy seams and neatly finished edges. Conventional sewing machines with a zigzag stitch work well, but the seams will not be as stretchy as those produced by a serger.
Choose an appropriate pattern. Four-way stretch fabrics are generally used for close-fitting garments such as exercise clothes, bike shorts and swimsuits. Make sure your pattern suits the fabric by checking the suggested fabrics on the pattern's envelope and instructions.
Sew a test swatch. Testing out your machine on a small swatch of fabric is critical when sewing with four-way stretch fabrics. This will help determine the proper thread tension, feed dogs settings and presser foot pressure. Doing these preparations will ensure your fabric won't gather, pucker or bubble and the seams won't pull out when stretched.
Cut out your pattern pieces, using ballpoint pins to secure the pattern to the fabric. Ballpoint pins slide through knit fabrics easily and are less likely to damage knits. Pin the pieces together to prevent them from sliding as you sew. Pin stabilising tape into shoulder seams if necessary.
Stretch fabrics slightly as you sew to ensure the threads don't pop while the garment is worn. Use the same technique while hemming a garment, to prevent threads from breaking.
Finish your garment. Seams on knit fabrics do not need to be finished because they don't ravel, unlike woven fabrics. Sergers produce finished seams, but for a more finished look, use your serger's roll hem function, or create a clean finish hem using a zigzag stitch. According to Threads Magazine, the double-needle topstitched hem is the one most commonly used on commercially made garments.
Use tissue paper between fabric pieces to prevent slippage. You can easily rip out the paper when you finished sewing.