What is Elastane Fiber?
Elastanes are elastomeric fibers, consisting of at least 85% polyurethane that are known by their trade names; usually Lycra in Europe and Spandex in the United States. They are segmented polyurethanes that are either melt or solvent extruded fibers after which they are either wet or chemical spun. The fibers are able to stretch up to seven times their length with an immediate full recovery to their original state without relying on being a crimped or coiled fiber. Elastane came to market in the late 1950s after being developed by DuPont, but it took a few years before it was widely accepted and became produced in a full-scale capacity by 1962. Elastanes have limited use when not blended with other fibers, but the sport swimwear industry capitalizes on the non-blended properties of pure elastane. When blended as a small percentage with other fibers, elastane give greater flexibility to a product.
Elastane is used in knitted and woven goods. Elastane yarn is incorporated in to the textile constructions where their high elastic extension and recovery are advantageous and increases property of the garments in the garments in which the fabric is used. Elastane yarns are never used alone in fabrics, but rather in combination with other yarns. Blended with other fibers like Nylon, Polyester, Cotton, Silk, Wool and other fibers either as bare yarns or as covered elastic yarns: Co-twisted, core spun, covered or co-tangled.
Typical elastic percentages in the elastane fabrics:
- Woven fabrics: 2–8%
- Swim/sportswear: 12–20%
- Corsetry: 10–45%
- Under wear: 2–5%
- Ladies hosiery: 2–12%
- Medical hosiery: 35–50%
Properties of Elastane Fiber
Elastane fibers are quite weak in comparison to other textile fibres, but they possess good resistance to chemical attack.
- Elasticity: This is the prime property of elastanes; they can be stretched four to seven times their original length with excellent holding power. The length of elongation is determined by the diameter of the yarn; the greater the weight of yarn the less extension.
Fig: General structure of elastane fibers - Resilience: The fibers are very flexible, and their rapid recovery rate ensures a flat, crease-free fabric.
- Absorption: Given elastane’s low absorption rate, a product made with 100% elastane will feel clammy next to one’s skin, which is why it is often blended with other fibers or core spun to enhance its absorbency e.g. with cotton.
- Strength: The breaking point of elastane will not be reached until it has reached full extension, which seldom happens under normal circumstances so, it is relatively strong and durable.
- Draping: As the fibers are flexible and lightweight they have good draping properties.
- Resistance: Elastanes are resistant to seawater, sunlight, shrinkage, mildew, insects, perspiration and most acids. An important aspect of elastane is that it is resistant to body oils, cosmetics and suntan lotion.
- Susceptible: Bleach can yellow and weaken the fibers. However, swimming pools use a mild form of calcium hypochlorite that is not strong enough to damage the fabric; plus, the temperature of the pool water tends to be relatively warm, not hot. Elastanes are thermoplastic and will melt at high temperatures becoming tacky at 175ºc whilst at 150ºc they yellow and lose their elasticity. Ironing elastane quickly on a low temperatures setting is advisable.
- Density (g/cm3): 1.21
- Moisture regain (%): 1.3
- Tenacity (cN/tex): 5–14
- Elongation at break (%): 400–650
- Abrasion resistance: Medium
Production Flow Chart of Elastane Fiber
Elastanes can be melted, wet, or dry spun; the latter method makes up approximately 90% of the elastane market. The commonest method is dry spinning. The solvent used is either dimethyl formamide or dimethyl acetamide. The solid filaments formed when the solvent evaporates are sticky and come together on touching. This property has the advantage that yarn of required linear density can often be readily produced. Once the required linear density is attained, yarns are treated with a finishing agent such as magnesium stearate or polydimethyl siloxane, to prevent further yarn adhesion.
Dry-Spun Process
Prepolymers are made from macroglycol that has been mixed with di-isocyanate.
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That solution is mixed with diamine to produce a diluted solvent.
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It is blended with delustre agents or coloured pigments before being filtered.
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It is then extruded through a spinneret.
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The fibers are heated by nitrogen and a solvent gas to set the fibers.
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The fibers are then washed in magnesium stearate to prevent the fibers from sticking to each other.
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The fibers are dried and the solvents are condensed and recycled.
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Filament fibers are created.
Finishes of Elastane Fiber
Fabric that contains elastane may have these finishes added, but care should be taken due to the fiber’s susceptibilities.
- Bleaching: Used to imbue the fabric with more whiteness. Care should be taken to use bleaches that do not contain chlorine.
- Calendering: Used to create smoother, more lustrous fabric. Temperatures should be kept low to ensure that the elastane does not lose its elasticity.
- Heat Set: Usually, this is carried out to enhance dimensional stability. Care should be taken with the temperature to ensure a minimal loss of elasticity.
- Water Resistant: Required for fibers with a high absorption rate.
Variations of Elastane Fiber
- Bare Yarns: It is used when a lightweight and flexible fabric is required. These fabrics are cheaper to produce, and they are incorporated into knitwear for tricot and circular-knit products e.g. swimwear, foundation garments, sock tops and stockings.
- Covered Yarns: The elastane is stretched to its maximum or near-maximum length before being covered with filament, textured or spun yarn. The covering may be single or double-layered; in the latter case, one yarn is wrapped in the S direction, and the other is wrapped in the Z direction. The elastane is then relaxed, which allows the covering yarns to extend with the elastane in use. These variations are used on Raschel and circular knitwear that require elasticity and good holding power for swimwear, foundation garments and hosiery.
- Core-Spun Yarns: A roving is twisted to make a sheath of staple fiber around the elastane. The texture of the yarn is determined by the sheath, and it has limited elasticity due to the twist in the staple sheath. The method is used for heavier fabrics, including both knitted and woven fabrics for dresses, tops, trousers, sportswear coats and uniforms.
Uses of Elastane Fiber
Elastane fiber is used in lightweight support hosiery, men’s hosiery and swimwear and foundation garments. It is widely used in clothing, including socks, tights, stockings, bra straps and side panels, underwear, jeans, leggings etc. It is often used more in women’s wear than in men’s wear due to the tight-fitting garments women require. It is also used for sportswear, where high stretch and holding power is required, including dance wear, cycling wear, swimwear, rowing gear, wrestling tops and aerobics outfits. Usually, only a small proportion of elastane is present in a fabric (2–5%), to provide the elasticity required. In foundation garments, however, as much as 45% elastane may be present. Lycra FreshFX is used for products that require all-day freshness. It can also be used in the medical field; for example, support stockings, bandages and orthopaedic braces. It can also be used for soft furnishings, such as mattress covers and three-piece suite covers. Covered elastane yarns are used extensively in cotton and woollen garments, often at a level of 2–5%.
Conclusion
Elastane fiber, also known as spandex or Lycra, is a synthetic fibre famous for its exceptional stretch and recovery properties. Elastane has reshaped modern clothing. Its ability to stretch, recover, and resist wear makes it indispensable across fashion, sportswear, and technical textiles. Elastane not only improves the functionality and aesthetics of clothing but also contributes to wearer confidence and mobility, making it a vital fiber in modern apparel and textile products.
References
[1] Ashford, B. (2016). Fibers to Fabrics.
[2] Kolanjikombil, M. (2018). The substrates: fibers, Yarn and Fabric. Woodhead Publishing.
[3] Sinclair, R. (2014). Textiles and fashion: Materials, Design and Technology. Woodhead Pub Limited.
[4] Kolanjikombil, M. (2019). Pretreatment of textile substrates. Woodhead Publishing.
[5] Kiron, M. I. (2024, December 24). Elastomeric fibers: Types, properties and uses. Textile Learner. Retrieved November 16, 2025, from https://textilelearner.net/elastomeric-fibers-types-properties-and-uses/
