Fabric Stretch and Recovery Testing for Leggings: A Buyer's Guide
When a legging fails in the market, the complaint is rarely about the seam. It is about see-through panels, sagging knees or a waistband that stops holding after two months. All three trace back to how stretch and recovery were specified, tested and controlled at the fabric stage.
The three numbers that matter
- Elongation at specified load – how far the fabric stretches, measured in both course and wale direction, typically at 5 kg or 10 kg.
- Growth (permanent deformation) – how much length remains after the load is removed and the sample rests.
- Recovery after cycling – behaviour after repeated extension and relaxation, which simulates real wear.
A common industry target for leggings is 180–250% elongation in the width direction and 90–140% in the length direction, with growth under 5% and recovery above 90% after ten cycles of 80% elongation.
Why opacity is a stretch issue
See-through fabric is usually a density problem. When elastane content is too low, or the stitch is too open, the fabric thins dramatically at maximum stretch. Raising GSM, tightening the stitch density or moving to a double-knit construction solves the issue more reliably than simply adding elastane.
Testing procedure in practice
- Condition samples for at least 4 hours at 20 ±2 °C and 65 ±4% RH.
- Cut specimens with a width of 50 mm and a gauge length of 100 mm.
- Apply a fixed load, hold for 60 seconds, measure, then release and allow 60 seconds of recovery.
- Repeat the cycle ten times and record the residual growth.
- Record the direction of testing, because a four-way stretch knit is rarely symmetric.
Fabric specification tips
- Specify a range rather than a single value, for example 210–240 GSM.
- State the elastane type, since heat-stable and chlorine-resistant options behave differently.
- Request a burst strength test alongside stretch; it predicts seam failure at the hip.
- Validate on a finished garment, not only on the greige roll.
Stretch standards written into the fabric specification at development stage are the cheapest quality control a brand can buy.
