Traditional double knitting is a form of knitting in which two colors or types of yarn are stitched on the same pair of knitting needles at the same time. Double-knit fabrics may be made by machinery, but still follow the same principle of using two threads at once. This provides a warmer and denser fabric and allows the knitter to make double-sided pieces without having to knit each side individually.
A popular way to use double knitting is to create pieces which are reversible, meaning one side has a different pattern than another on the same piece. This means one sweater, for example, can be worn with one pattern on the outside, or turned inside out to display another pattern for a different look. Doing this with single-stitch knitting would require knitting one side of the piece, then the other and then binding them together.
Double knitting begins with casting on one stitch in one color, then the next stitch in the other color and staggering the stitches in that way until he or she has as many as desired. The more colors or types of yarn added, the more complicated the double knitting process might become and the more complex the pattern will be. It is suggested that beginners start with two colors and a simple pattern to practice before going for complex pieces.
While working the pattern, the knitter will start the first row by knitting one stitch in one color and then purling one stitch in the other color. The next row will begin by purling one stitch in one color and then knitting in the next, and the whole piece is created by alternating the rows in this way. For example, a person knitting with blue and white yarn will begin by casting on the yarn in an alternating pattern of blue and white. Then he or she will begin by knitting one stitch in white and then purling one stitch in blue until the end of the first row. The second row will begin with purling one white and then knitting one blue.
Double knitting has also found its way into commercial fabric production. Many garments and blankets sold by small and large retailers may feature double-knit fabrics created by machines for added durability, comfort, and warmth. Fabric blends are often double knit fabrics with two or more strands of different types of threading, such as cotton and polyester.