When you have spent time completing a sewing project, the last thing you want is for the edges of the fabric to fray. Most fabrics will fray when they are cut, with some being worse offenders than others, and some fabrics, like felt, do not fray at all. In a sewing project, such as a garment, the seam allowance provides a little extra fabric. This allows for neatening the edges which helps to prevent fraying. For projects such as applique, that have no stitched seam allowance, there are alternative methods to prevent fraying.
Sew the seam closed using the recommended seam allowance on your pattern.
Trim the seam allowance to half an inch away from the stitches, then either press the seam with the seam allowance closed, or open out both sides of the seam allowance and press the seam flat.
Set your sewing machine to the zigzag setting, then zigzag down the very edge of the seam allowance fabric. If you're finishing both layers of the seam allowance together, zigzag through both layers. If you're finishing each side of the seam allowance individually, zigzag along the edge of each side of the seam allowance in turn.
Pin your pattern to your fabric as normal.
Cut around the pattern with pinking shears. Pinking shears make a zigzag cut in the fabric, which helps to prevent fraying.
Remove the paper pattern from the fabric, and stitch the pattern pieces together as normal.
Alternative methods of preventing fraying on the edges of fabric include using fabric glue around the lines of the pattern before cutting. This technique may work for applique patterns, but may not work for garments intended to be worn as the glue can cause stiffening of the fabric. A second alternative is to use a product designed to prevent fabric fraying. Such products are widely available in haberdashery or crafts stores and can be bought as a spray-on product or as a liquid. These are handy to help prevent fraying in such areas as buttonholes or when sewing on motifs, and will normally withstand regular washing.