ISO 13934-1

What the test does

A 50 mm wide strip of woven fabric is clamped across its entire width in two flat jaws set a fixed distance apart. One jaw travels away from the other at a constant speed until the strip ruptures, while force and jaw separation are recorded continuously. The peak of that curve, and the extension reached at the instant of the peak, are the two reported results.

What it measures, and why it matters

The method reports maximum force in newtons and elongation at maximum force as a percentage, separately for the warp and the weft, because a woven fabric is anisotropic. Maximum force is the figure written into purchase specifications for apparel, furnishing and technical wovens, so it governs lot acceptance and supplier qualification. Elongation at maximum force distinguishes a stable construction from one that will distort under load, and both figures drop measurably after abrasion, laundering or UV exposure, which is what makes the pair useful in failure investigations.

Strip and directions

Specimen width

50 mmClamped across its FULL width, unlike a grab test.

Gauge length

200 mm, or 100 mm for high-extension fabrics

Both directions

Warp AND weft, reported separately

Fraying the edges

To an exact yarn countStrips are cut wider and yarns removed from each edge until exactly the right number remain — that is what makes the width a yarn count rather than a ruler measurement.

Specimen spacing

No shared yarns between replicates

Conditioning

Textile standard atmosphere

Discard

Any break within 5 mm of a jawThat is a grip failure and does not represent the fabric.

Test speed

200 mm gauge, elongation at maximum force below 8 %

20 mm/min (10 %/min)

200 mm gauge, elongation at maximum force 8 % to 75 %

100 mm/min (50 %/min)

100 mm gauge, elongation at maximum force above 75 %

100 mm/min (100 %/min)

Tolerances

Rate to ±10 %, gauge length to ±1 mmTable 1 picks the pair from the fabric's expected elongation, so the band has to be known or estimated before the run.

Pretension

Applied to remove slackSmall, and defined — enough to straighten the strip without stretching it.

Calculations

How the test runs

1. 01Condition the fabric in the textile standard atmosphere.
2. 02Cut strips wider than 50 mm in both warp and weft directions.
3. 03Fray each edge back until exactly the right number of yarns remain, giving a true 50 mm width.
4. 04Space specimens so no two share yarns.
5. 05Set the gauge length — 200 mm, or 100 mm for a high-extension fabric.
6. 06Clamp across the full width, square and without skew.
7. 07Apply the defined pretension to remove slack.
8. 08Run at the rate set by the expected elongation.
9. 09Record maximum force and the extension at that maximum.
10. 10Discard any break within 5 mm of a jaw and replace it.
11. 11Report warp and weft separately.

Grips and fixtures for this method

Two face setsTJ-26

100mm Wide Vice Action Grips

Wide vice-action jaws hold a 50 mm strip across its whole width without skew — a strip gripped unevenly loads one edge first and breaks low.

Specifications

Standard 25 mm

Pneumatic Vice Action Grip

Constant air pressure keeps clamping identical between specimens, which matters over the replicate counts textile testing uses.

Specifications

What the report has to contain

• Reference to ISO 13934-1
• Fabric identification, construction and finish
• DIRECTION for every result — warp or weft
• Gauge length used
• Rate of extension and the pretension applied
• Conditioning atmosphere
• Maximum force in newtons
• Elongation at maximum force
• Number of specimens per direction, mean and coefficient of variation
• Any specimen discarded, with the reason

What the machine must be capable of

The method calls for a constant-rate-of-extension frame — the moving jaw holds its speed throughout, rather than tracking load. Most apparel and furnishing wovens break between roughly 100 N and 1.5 kN on a 50 mm strip, so a 5 kN load string covers the great majority of the work; heavy technical wovens such as sailcloth, airbag fabric and coated industrial cloth can push past 5 kN, which is why textile laboratories handling them specify 10 kN. Force indication must meet ISO 7500-1 Class 1.

Gauge length is 200 mm, reduced to 100 mm where elongation at maximum force is expected above 75 %. Speed is keyed to that expectation: on the 200 mm gauge, 20 mm/min below 8 % elongation and 100 mm/min from 8 % to 75 %; on the 100 mm gauge above 75 %, 100 mm/min. Rate must hold to ±10 %, because fabric strength is rate-sensitive.

No extensometer is required — elongation is taken from jaw separation, so every millimetre of grip slip or frame compliance is counted as fabric stretch. Jaws must be flat-faced and at least 60 mm wide so the full 50 mm of fringed width is clamped uniformly; narrower faces load the centre of the strip and force an early edge failure. Capstan jaws are the fallback for fabrics that slip or break at the clamp. A pretension is applied to straighten the strip and define the starting length. The laboratory itself is part of the instrument: testing is done in the same conditioned atmosphere, and the alternative 23 °C / 50 % RH atmosphere may be used only by agreement between the parties and must be reported.

What goes wrong in practice

Jaw breaks are the standard invalidation — the strip fails at the clamp line, reads low, and must be replaced. Slippage is harder to catch, because with no extensometer the fabric creeping out of the jaws is recorded as extension and inflates elongation. Fringing errors are specific to this method: one thread too many leaves under 50 mm carrying the load, and maximum force falls proportionately. Conditioning drift is invisible — hygroscopic fibres change strength with moisture regain, so a warm, dry laboratory produces a consistent offset.

ISO 13934-1 or ASTM D5034

These give different numbers on the same fabric by design, and neither converts to the other. A specification that names a breaking force without naming the method has not specified anything a supplier can test against.

Questions we are asked about this test