Tensile Strength and Elongation Testing for Knit and Woven Fabrics
Tensile testing defines the force a fabric withstands before breaking, and elongation at break is often the more useful figure.
This article sets out what the requirement involves, how to specify it and how to verify it before bulk production.
Grab versus strip testing
The grab test suits woven and knit fabric behaviour in garments, while the strip test characterises the material itself.
Experience shows that small specification decisions here have an outsized effect on the customer experience.
Specimen preparation
Cutting direction, width, gauge length and edge fraying all affect the measured breaking force.
Write the requirement into the fabric specification as a numeric range with the test method named, so buyer and mill measure the same thing.
- Confirm the numeric range and the test method in the specification
- Keep an approved physical standard at the machine
- Retest after the agreed care regime before shipping
Interpretation for apparel
High elongation with moderate force suits knitwear, while low elongation with high force suits structural wovens.
Escalate deviations immediately, as a small change early in the run is cheap to correct and costly to fix later.
After-treatment comparison
Tensile results before and after finishing show the strength cost of brushing, calendering or bleaching.
Where a claim will be published, check that the test method supports the exact wording used in marketing.
- Request test reports on production fabric, not on development samples
- Verify the sampling plan and the number of specimens
- Store reports with roll or lot identification for traceability
Reporting requirements
Record the test standard, specimen dimensions, clamp speed and both breaking force and elongation.
Keep a buffer in the schedule for one additional approval round, because most programmes use it.
Summary
Used as a checklist in development and again before shipment, the points above prevent the most common and most expensive failures.
