What is Elastane (Spandex)?

Elastane is a synthetic fiber of which at least 85% by mass is segmented polyurethane, and which returns quickly and almost completely to its original length after being stretched to three times that length (Regulation (EU) 1007/2011, Annex I). It is usually used in low percentages together with other fibers, to give a fabric stretch and recovery. In Turkey it is commonly called likra (Lycra), while the Turkish form of the fiber name is elastan; in the US its generic name is spandex.

Elastane, spandex and Lycra

The three names describe the same fiber family, but not at the same level.

• Elastane: the EU fiber name.
• Spandex: the generic name in the US; the FTC defines it for fibers whose fiber-forming substance is at least 85% segmented polyurethane (16 CFR 303.7).
• Lycra (likra in Turkish): a brand name. LYCRA® is now a registered trademark of The LYCRA Company; the fiber was developed at DuPont in 1958. The company itself describes spandex and elastane as generic names for the same fiber class (The LYCRA Company). Cingü (2022) writes that in Turkey the name Lycra is used like a generic name. In specifications and on labels, write “elastane”.

Not every elastic fiber is elastane. In the EU list, elastodiene (no. 42), elastomultiester (no. 45) and elastolefin (no. 46) are separate fiber names; for the last two the criterion is stretching to one and a half times and recovering, not three times (Annex I).

Structure and properties

• Chain structure: The chains contain soft and hard regions. The soft regions let the fiber stretch and return to its original state; the hard regions bind the chains to one another (Saçak, 2002, cited in Cingü, 2022).
• Stretch: According to one source it can be stretched to about 4–7 times its length (Cingü, 2022, in a paragraph based on McCann, 2015).
• Moisture: It is a hydrophobic fiber with low water absorbency (Yeşil, 2003, cited in Cingü, 2022). The moisture allowance that the EU regulation accepts when calculating fiber content is 1.5% (Annex IX).

How elastane is used in fabric

Elastane is not used alone in a fabric; it sits next to another yarn.

• Bare elastane: Bare elastane yarn is generally used in circular knitting (Tezel, 2007, cited in Cingü, 2022). The count of elastane yarn is given in dtex; in Cingü’s research, bare elastane yarns of 22–78 dtex were used.
• Covered and core-spun yarns: Filament or staple fiber is wrapped around the elastane. The types include single-covered and double-covered yarn, air-entangled yarn and core-spun yarn (Cingü, 2022).
• Feeding in single jersey and rib: If elastane is fed on every course, the fabric is “full elastane” (colloquially full lycra’lı in Turkish); if on every second course, it is “half elastane”. In rib, elastane is fed only to the dial needles, or to both dial and cylinder needles (Tezel, 2007, cited in Cingü, 2022).
• Percentage: In trousers about 2% elastane can be enough to hold shape, whereas swimwear, corsetry and sportswear can use 15–40% (McCann, 2015, cited in Cingü, 2022).
• Effect on fabric behavior: In a study with cotton rib and single jersey, adding elastane increased fabric weight and reduced shrinkage and spirality (Halim and Fahad, 2019, cited in Cingü, 2022).

You can find spandex yarn suppliers in the Spandex Yarn category, and makers of swimwear and socks that use elastane in Swimwear and Beachwear and Socks and Hosiery.

How to verify the elastane content

1. Write it as a percentage. In specifications and on labels, write the composition like “95% cotton, 5% elastane”.
2. Ask for laboratory analysis. ISO 1833-20 determines the elastane percentage, by the dimethylacetamide method, in mixtures of certain elastane types with cotton, viscose, cupro, modal, lyocell, polyamide, polyester or wool; it does not apply if acrylic fiber is present. ISO 1833-12 or ISO 1833-21 is used for some mixtures.
3. Check on a sample. Cutting a sample from the fabric, unraveling the yarns, weighing the elastane and the other yarn separately and then working out the ratio is another method (Cingü, 2022).

Care

Do not use chlorine bleach on fabric containing elastane (spandex); if needed, choose a bleach suitable for colored laundry. Washing in warm water, by hand or machine, and drying on a line or at low heat in a dryer are recommended. Iron on a low setting, briefly, without leaving the iron in one spot (FabricLink). Always follow the product’s care label.

Frequently asked questions

What percentage of elastane should a fabric have?

There is no single right percentage; it is chosen by product. The sources cite ranges such as about 2% for trousers and 15–40% for swimwear and sportswear (McCann, 2015, cited in Cingü, 2022). Confirm the target percentage, and how the elastane is fed into the fabric, on a sample.

Are elastane and Lycra the same?

In everyday Turkish usage they describe the same fiber. Lycra is a brand name; the generic name of the fiber is elastane, and spandex in the US.