Intarsia knitting is a knitting technique that uses multiple colors of yarn to create knitted pictures or multicolored patterns. Along with Fair Isle knitting, it is one of the most common multicolor knitting techniques. Intarsia knitting projects are usually knit flat on two needles, using a separate ball of yarn for each section of color in the pattern. The technique can be applied to any type of knitting project, including sweaters, shawls, bags, gloves, and socks. Almost any type of yarn can be used, as long as the different colors of yarn are of similar yarn weights, or strand thicknesses. Most intarsia patterns rely on a chart in the form of a grid of squares that provides a visual representation of which colors go where.
Each separate section of color in an intarsia knitting pattern requires a separate ball of yarn. For instance, if the pattern features a red apple centered on a green background, the necessary materials for knitting this pattern will include one ball of green yarn for the green section before the apple, one ball of red yarn for the apple itself, and a second ball of green yarn for the green section after the apple. Knitting with multiple balls of yarn at once can sometimes cause the yarn to become tangled, so many knitters wind their yarn around yarn bobbins to avoid this problem. Yarn bobbins are usually small plastic spools that can be purchased at craft stores, although homemade versions can also be created using a clothespin or even a small piece of stiff cardboard.
Intarsia knitting is a fairly easy technique to learn since it is usually knit in stockinette stitch, which is a simple and common knitting stitch that has all the knit stitches on the outside of the fabric and all the purl stitches, or knit stitches in reverse, on the inside of the fabric. The most complicated part of any intarsia knitting pattern is changing colors. When a new yarn is introduced, it is not actually connected to any of the existing knit stitches, so holes and gaps can appear in the knitting where the color changes are made. To fix this problem, a knitter will twist the new color of yarn over the last color used, trapping the old yarn between the new yarn and the knitting itself and eliminating any holes. The twist is always performed on the inside of the knit fabric so it can't be seen when the finished knit piece is worn.
Most intarsia knitting patterns are charted on knitting graph paper. Regular graph paper does not have the right proportions for knitting patterns, since it is made up of perfect squares and knitting stitches are wider than they are tall. On an intarsia chart, each square of the grid will be filled in with a particular color, so that the knitter can anticipate when and where in the knitting process she needs to change colors. Some knitters may choose to use the original color scheme presented in the pattern, while others may choose to substitute different colors to suit their tastes.