Soy yarn is yarn produced with fibers derived from soy. Companies that make this yarn usually use byproducts of food manufacturing that would normally be discarded, putting the waste through an extrusion and wet spinning process to create fibers that can be spun into yarn. Many knitting stores sell soy yarn and it is also possible to buy raw soy fiber to spin at home, for people who are interested in making their own versions of this yarn.
Industrial manufacturing of soy fiber dates to the 1930s, and experienced a resurgence in the early 2000s as crafters became more interested in using natural fibers for their projects. Soy fiber can be used to make fabric, as well as yarn, and in addition to being used as a standalone, it can be integrated into fiber blends. Soy/wool and soy/cotton blends are both readily available, bringing out the best traits of both fibers.
Pure soy yarn is very strong and soft. It is also highly stretchy and can feel slippery or slick, much like silk yarns. It can be spun in a variety of weights and is also available in the form of novelty yarns, such as yarn tubes or ribbons. Like many other yarns made from plant fibers, soy yarn takes dyes very well. Knitters should be aware that it is not always colorfast through the first few washings and may bleed slightly, although the color of the yarn usually remains crisp and clear.
Raw soy fiber for spinning is sometimes available at yarn and knitting stores. It can also be ordered directly from companies that make soy yarns. These companies also sell undyed yarns for people who would like to dye their own yarns. Dyes can be purchased from dye companies or made at home. Some dyes can cause the texture of the yarn to roughen slightly, an important consideration for yarn that will be used in knitted garments worn directly against the skin.
Working with soy yarn requires no special tools or skills. Knitters may find it helpful to make several test swatches first to get familiar with the yarn and the gauge. These swatches can also be washed to assess colorfastness. Unless the care directions say otherwise, products made with soy yarn can usually be washed in cool to warm water with gentle soaps. Handwashing may be recommended for hand knitted projects, and the piece should be blocked by laying it out flat after washing to help it retain shape.