Clothing Fabric Breaking Strength Testing: Standards, Methods, and Applications

Clothing fabric breaking strength testing measures the maximum tensile force a woven textile can withstand before rupture, making it one of the most fundamental indicators of garment durability and fabric quality. This guide explains the testing principles, specimen preparation, key international standards such as ISO 13934 and ASTM D5034/D5035, and the practical applications of breaking strength evaluation for apparel fabrics.

Technical Overview

Breaking strength, also known as breaking force or maximum force, is the greatest tensile load that a fabric specimen can resist before it ruptures when stretched to failure. For clothing fabrics, this property directly reflects the ability of a garment to withstand pulling, stretching, snagging, and everyday mechanical stress without tearing or seam failure.

The test is performed on a constant-rate-of-extension (CRE) tensile testing machine. A rectangular fabric specimen is clamped between two jaws and extended at a defined speed until it breaks. During the process, the instrument records a force-elongation curve, from which the maximum force (expressed in newtons, N, or pound-force, lbf) and the elongation at maximum force (expressed as a percentage) are determined.

The principal standards governing this test are the ISO 13934 series (adopted in Europe as EN ISO 13934 and in China as GB/T 3923), which distinguishes between the strip method (Part 1) and the grab method (Part 2), and the equivalent North American standards ASTM D5035 (strip method) and ASTM D5034 (grab method). Because breaking strength is sensitive to moisture, temperature, specimen geometry, and machine settings, strict adherence to the selected standard is essential for obtaining comparable and reproducible results.

Testing Samples

Applicable Fabric Types

• Woven apparel fabrics such as shirting, suiting, poplin, and twill
• Heavy-duty woven fabrics including denim, canvas, and workwear materials
• Lining fabrics and interlinings used in garment construction
• Home textile and technical woven fabrics where tensile performance is specified

Knitted fabrics are generally not evaluated by this tensile method because their structure deforms excessively under uniaxial loading; they are instead assessed by bursting strength methods such as ISO 13938 or ASTM D3786.

Specimen Dimensions

For the strip method, specimens are cut with an effective width of 50 mm ± 0.5 mm (or 25 mm for narrow fabrics) and a length sufficient to allow a 200 mm gauge length, typically at least 300 mm in total. If yarns fray during cutting, a wider specimen may be cut and raveled down to the exact width. For the grab method, specimens are typically 100 mm wide and at least 150 mm long, because only the central portion of the width is gripped by the jaws.

Sampling Rules

A minimum of five specimens is tested in each fabric direction (warp and weft). Specimens must be taken diagonally across the fabric width, away from the selvedge and cut edges, and no two adjacent specimens should contain the same set of yarns. Areas with folds, creases, visible damage, or irregularities must be avoided.

Conditioning

Specimens are conditioned in the standard atmosphere defined in ISO 139 (20 °C ± 2 °C and 65 % ± 4 % relative humidity) until moisture equilibrium is reached, typically at least 24 hours. Conditioning is critical because hygroscopic fibers are strongly affected by moisture content: cotton becomes stronger when wet, whereas regenerated cellulosic fibers such as viscose lose considerable strength.

Testing Items

The principal parameters reported in a breaking strength test include:

• Breaking force (maximum force) in the warp direction, in N or lbf
• Breaking force (maximum force) in the weft direction, in N or lbf
• Elongation at maximum force, expressed as a percentage of the initial gauge length
• Elongation at break, where required by the specification
• Statistical treatment of results, including the arithmetic mean, coefficient of variation, and minimum values for each direction

Testing Methods

Strip Method (ISO 13934-1 / GB/T 3923.1 / ASTM D5035)

The full width of the specimen is gripped in the jaws, so every yarn across the width contributes to the measured force. Under ISO 13934-1, the gauge length is 200 mm and the rate of extension is 20 mm/min for fabrics with elongation at maximum force of 75 % or less, and 100 mm/min for more extensible fabrics. A pretension is applied according to the fabric mass per unit area: 2 N for fabrics up to 200 g/m², 5 N for fabrics between 200 g/m² and 500 g/m², and 10 N for fabrics above 500 g/m². ASTM D5035 typically uses a 75 mm gauge length with a testing speed of 300 mm/min.

Grab Method (ISO 13934-2 / GB/T 3923.2 / ASTM D5034)

Only the central portion of the specimen width is clamped, with jaw faces of approximately 25 mm × 25 mm at the front and 25 mm × 50 mm at the rear. This modification reduces yarn fraying and concentrates the stress in the gripped region, which better simulates localized stress on a garment. ISO 13934-2 specifies a 100 mm gauge length and an extension rate of 100 mm/min, while ASTM D5034 uses a 100 mm gauge length at 300 mm/min. Grab results are typically higher than strip results for the same fabric because the unclamped side yarns reinforce the stressed zone.

Equipment Requirements

Testing must be carried out on a calibrated CRE tensile testing machine conforming to the requirements of ISO 13934 or ASTM D76. The force-measuring system should be accurate to within ± 1 % of the indicated value, and jaw faces must grip the specimen securely without slippage. Regular calibration and verification by accredited third-party laboratories ensure traceability of the results.

Invalid Results and Retesting

If a specimen slips in the jaws, or breaks within 5 mm of the jaw edge and yields a result below the mean of the valid breaks, the result is considered invalid and an additional specimen must be tested. This practice prevents jaw-related artifacts from artificially lowering the reported breaking force.

Data Processing and Reporting

The arithmetic mean breaking force and elongation are calculated separately for the warp and weft directions, together with the coefficient of variation. The test report should state the standard used, the specimen type and dimensions, the gauge length, the extension rate, the conditioning atmosphere, and any deviations or invalid results encountered.

Applications

• Incoming fabric inspection and supplier qualification for garment manufacturers and brand owners
• Process control in weaving, dyeing, and finishing, since excessive chemical or thermal treatment can significantly reduce fabric strength
• Compliance verification against product specifications and procurement requirements for uniforms, workwear, and protective clothing, many of which define minimum breaking force limits or graded performance classes
• Research and development of new fiber blends, fabric constructions, and finishing recipes
• Evaluation of strength retention after repeated laundering, abrasion, aging, or UV exposure
• Failure analysis and dispute resolution, where accredited third-party laboratories provide objective evidence of whether a fabric meets the contracted technical requirements

FAQ

What is the difference between breaking strength and tear strength?

Breaking strength measures the force required to rupture a fabric under continuous uniaxial tension applied across its full width, while tear strength measures the force needed to propagate an existing cut or tear. Both properties are important for garments, but they describe different failure modes and are tested by separate methods.

How do I choose between the strip method and the grab method?

The choice depends mainly on the target market and the applicable specification. ISO-oriented and GB-oriented requirements typically reference the strip method, whereas many North American specifications reference the grab method. The grab method is often preferred for fabrics that fray easily or when a coated fabric is tested, while the strip method evaluates all yarns across the width and is preferred for comparative fabric analysis.

What breaking force values are typical for clothing fabrics?

Values vary widely with fiber content, yarn linear density, and fabric construction. Commercial specifications for lightweight shirting fabrics commonly reference minimum breaking forces in the range of approximately 150 N to 250 N, whereas denim and heavy workwear fabrics frequently exceed 600 N to 1000 N. The applicable limit should always be confirmed against the specific product standard or purchase contract.

Why do different laboratories sometimes report different results?

Differences can arise from the standard and method version applied, the conditioning atmosphere, specimen preparation, applied pretension, jaw type and pressure, extension rate, and sampling location. Using harmonized test methods and properly calibrated equipment minimizes interlaboratory variation.

Can breaking strength testing be performed after washing?

Yes. Testing fabrics after a defined number of laundering cycles is a common way to assess strength retention and the durability of finishes. The same strip or grab procedure is applied, but the preconditioning history must be documented in the report.