Elastane yarns are characterised by their ability to recover from stretch. BISFA describes them as "a fibre composed of at least 85% by mass of a segmented polyurethane which, if stretched to three times its unstretched length, rapidly reverts substantially to the unstretched length when the tension is removed". Although elastane was first synthesised in 1937, it was not commercialised as a fibre until 1958.

Properties and End-Uses
In addition to their remarkable stretch and recovery properties, elastanes resist perspiration and cosmetic oils, are easily washable, are dyeable and have moderate abrasion resistance. Elastane yarns are often covered with another fibre before use. This provides more bulk and improves abrasion resistance. The main end-uses for the yarns are garments and other products, where comfort and/or fit are important.