Since its invention in 1958, spandex, also known as elastane or by its trademark name, Lycra, has revolutionized the textile industry and clothing design. Unlike its predecessors, rubber and elastic fibers, spandex can stretch up to 500 times its starting length and then return to its original size. It can also be spun into fine filament threads, making it ideal for blending with other fibers to add elasticity.

Knit fabrics can be manufactured with or without spandex. A typical example of a non-spandex knit is a sweatshirt knit. While comfortable, these knits lack “memory,” meaning over time, they bag out in places where the body bends: think knees, elbows, and the seat. Even washing and drying in high heat won’t coerce the fibers back into shape once they have stretched out. But with spandex added to the fibers, the same weight of knit retains its memory and goes back to its original dimensions. Spandex also has the advantage of strengthening many fibers.

Even in small percentages, spandex has been a game changer for knitted fabrics. The addition of spandex fibers has made possible many of the fabrics we use daily. Included in everything from underwear to outerwear, spandex has allowed the invention of fabrics that give freedom of movement while snapping back to their original shape. Because of its tensile strength, it adds longevity to certain fabrics and the garments made with them. Let’s examine some of the types, characteristics, and construction tips for fabrics containing this revolutionary fiber.

There are three general types of spandex knits available to the home sewing enthusiast: jersey, or single knits; double knits; and sweater knits. There are thousands of variations within these categories but we’ll concentrate on these. Although these knits behave differently from basic woven fabrics, with a few adjustments to your…