Bark Yarn · Blog
What is elastane? Choosing yarn for stretch and recovery
Elastane, spandex and elastic yarn terminology: stretch, permanent extension and care checks for socks, ribbing and knitted fabrics.
Elastane and spandex
Elastane is a synthetic fibre based on segmented polyurethane, used for high extension and recovery. It is also known as spandex. It is usually combined with other fibres; its percentage in a blend is not the same measure as a fabric’s percentage stretch.
Covered yarn and knit construction
Elastane can be used in structures covered with other yarns. Fabric behaviour depends on feeding, tension and knit design as well as the fibre. Two fabrics with the same elastane percentage should therefore not be assumed to have identical tightness.
Two separate questions for the sample
How far does the product stretch, and how well does it recover when released? Assess these separately. For ribbing, a sock cuff or fitted knitwear, define the target dimensions and duration of use. Measure residual extension after the trial; do not use the initial feeling when stretched as the sole acceptance criterion.
Care, sizing and the technical specification
Record measurements again after the intended washing and drying conditions. Match the yarn specification, blend percentage and production settings to the sample. A trade name is not the generic name for every elastane fibre. Specifying elasticity expectations does not constitute a guarantee of finished-product comfort or medical performance.