Synthetic Elastomeric Yarn is commonly referred to as spandex yarn which was first produced in the 1950s by the German textile manufacturer Bayer Fibers. Spandex was originally designed to be a synthetic replacement for natural latex rubber. Bayer Fibers produced their brand of spandex under the name of Dorlastan.

Subsequently, DuPont Fibers produced their brand of spandex under the name Lycra. In some parts of the world today, the name Lycra has become the generic name for elastomeric spandex yarn. DuPont Fibers sold their spandex business unit to the company Invista which now owns the brand Lycra. In today’s world of elastomeric fibers, there are many companies producing spandex yarns all around the world.

Spandex yarns are produced as a filament yarn, meaning the fiber is continuous and with very large percentage of elongation and recovery. Spandex yarns are sold using the unit of measures of denier or decitex. The common deniers for spandex yarns range from 10 denier to 1,680 denier. At one point, some manufacturers of spandex made a denier past 5,000 denier.

Spandex yarns are used in a wide range of textile applications. Spandex yarns can be direct knit into a fabric. Spandex yarn can be introduced into a fabric as a “covered spandex” meaning the spandex yarn has a component yarn wrapped around the spandex. An example of a covered spandex application is the production of knit pantyhose and socks. Spandex yarn also is placed into elastic narrow fabrics. Examples of an elastic narrow fabric are: the elastic in a waist-band in underwear or in a bra strap.

Spandex yarns have been a primary component of baby diapers and adult incontinent products. The spandex yarns give these products their stretch and recovery attributes. If you read “latex free” on a textile garment, this usually means there is no natural latex rubber in the product and spandex is the replacement for the rubber.

Spandex yarns can be sensitive to light and humidity. If the elastomeric spandex fibers are not stored properly, there can be some degradation in the performance of the yarn. There has been a textile industry practice of discounting spandex fibers if they appear to have any age to them. However, providing the spandex yarns are stored correctly, spandex yarns with some age have been able to knit without any imperfections. The larger the denier, typically, the more “shelf life” the spandex yarn may have.

The interesting point of first quality elastomeric yarn is the size or the denier of the yarn is exact when sold as a first quality product. If the 40 denier spandex yarn is first quality, it is indeed a 40 denier—not a 39 or a 41 denier, but a 40 denier. When a spandex yarn does have a variation in the denier, it must be classified as a substandard or second-quality yarn.

A substandard or second-quality spandex yarn can still be used on a knitting machine; however, it is highly recommended the downgraded yarn be used in conjunction with a spun yarn such as cotton, cotton blended yarns, spun polyester or spun rayon, for example. If the substandard or second-quality spandex yarn is knit with a 100% filament yarn, there is a substantial possibility of bare or streaks to appear in the fabric.

A substandard or second-quality spandex yarn can be run successfully into a yarn covering application. This process will typically cover the imperfection of the denier variation of the elastomeric yarn. When using a substandard or second-quality spandex yarn in covering, it helps to have the covering machine run at a slower speed.

It is recommended to place substandard or second-quality spandex yarn into non-critical products like unbranded product lines. Products designed for the informal markets or promotional markets or for the budget-minded product category are ideal homes for substandard or second-quality spandex yarns.