Dry state breaking strength determination is a fundamental tensile test that measures the maximum force a textile fabric or yarn can withstand before rupture when tested under standard conditioned (dry) atmospheric conditions. This comprehensive guide covers the testing principles, internationally recognized standards such as ISO 13934, ASTM D5034/D5035, and GB/T 3923, specimen preparation, procedural requirements, and practical applications across the textile and materials industries.
Technical Overview
Dry state breaking strength determination is a core mechanical performance test used to evaluate the tensile integrity of textile materials. The test measures the maximum tensile force, expressed in newtons (N), that a specimen can resist before rupturing when tested in its conditioned, dry state. Because the vast majority of textile products are used and stressed under ambient dry conditions, this parameter serves as one of the most important indicators of fabric durability, processability, and overall quality.
The term "dry state" refers to specimens that have been conditioned in a standard laboratory atmosphere prior to testing, in contrast to wet breaking strength tests in which specimens are fully soaked in water before extension. Conditioning is typically performed according to ISO 139 or ASTM D1776 at 20 ± 2 °C and 65 ± 4 % relative humidity, ensuring that moisture content is at equilibrium and that results are reproducible between laboratories.
Dry state breaking strength is widely specified in product standards, purchase contracts, and certification schemes. The principal reference methods include the strip method described in ISO 13934-1, ASTM D5035, EN ISO 13934-1, and GB/T 3923.1, and the grab method described in ISO 13934-2, ASTM D5034, EN ISO 13934-2, and GB/T 3923.2. All of these procedures are performed on constant rate of extension (CRE) tensile testing machines in accredited third-party laboratories and in-house quality control facilities worldwide.
Testing Samples
Woven Fabrics
Woven fabrics are the most common substrate for dry state breaking strength testing. Specimens are prepared in both the warp (lengthwise) and weft (crosswise) directions, as the two directions frequently exhibit significantly different strength values due to yarn density, twist, and weave structure. Typical products include shirtings, denim, workwear fabrics, pocketing fabric, linings, and canvas.
Knitted Fabrics
Knitted fabrics can be tested using the strip method with appropriate modifications, since their high elasticity and tendency to curl at the edges can complicate specimen mounting. Ravel strip techniques, wider specimens, or specialized jaw liners may be employed to obtain valid results for T-shirts, underwear, sportswear, and hosiery materials.
Nonwoven and Coated Fabrics
Nonwoven fabrics used in medical, hygiene, filtration, and interlining applications are tested to verify web consolidation and bonding strength. Coated and laminated fabrics, such as those used for tents, awnings, protective clothing, and flexible membranes, are also evaluated, with the coating often contributing to the overall breaking force.
Technical and Industrial Textiles
Geotextiles, filter fabrics, conveyor belt fabrics, tire cord fabrics, and reinforcement textiles are routinely tested in machine and cross-machine directions. For these materials, dry state breaking strength is frequently a critical safety-related specification, and additional parameters such as elongation at maximum force and seam strength may be assessed alongside it.
Yarns and Sewing Threads
For linear textile materials, the equivalent property is typically determined as breaking force and breaking tenacity under standards such as ISO 2062 or ASTM D2256, using single-strand tensile testing equipment with appropriate pretension and gauge length settings.
Testing Items
A typical dry state breaking strength determination report includes the following measured and calculated parameters:
- Breaking force (maximum force) in the warp direction, expressed in newtons (N)
- Breaking force (maximum force) in the weft direction, expressed in newtons (N)
- Elongation at maximum force, expressed as a percentage of the initial gauge length
- Elongation at break, where applicable and distinguishable from elongation at maximum force
- Breaking tenacity for yarns, expressed in centinewtons per tex (cN/tex)
- Arithmetic mean value for each direction based on the required number of valid specimens
- Coefficient of variation and, where required, the 95 % confidence interval of the mean
- Details of the test method used (strip or grab), gauge length, extension rate, and specimen dimensions
- Conditioning atmosphere and any deviations or observations, such as jaw slippage or slippage-type failures
Testing Methods
Specimen Preparation and Conditioning
Specimens are cut representative of the bulk fabric, avoiding creased, damaged, or selvedge-adjacent regions. For the strip method, specimens are typically 50 mm or 25 mm in effective width with sufficient length to allow mounting in the jaws plus the specified gauge length. Specimens are then conditioned in a relaxed, freely hanging state in the standard atmosphere for a minimum period, commonly at least 24 hours, or until moisture equilibrium is reached.
Strip Method
The strip method, specified in ISO 13934-1, ASTM D5035, and GB/T 3923.1, involves clamping the full width of a narrow rectangular specimen in the upper and lower jaws of a CRE tensile tester. The specimen is extended at a constant rate until rupture, and the maximum force recorded by the force-measuring system is taken as the breaking force. A gauge length of 200 mm with an extension rate of 20 mm/min is commonly applied, although alternative gauge lengths of 100 mm with corresponding rates of 50 mm/min or 100 mm/min are permitted depending on the elongation characteristics of the material.
Grab Method
The grab method, specified in ISO 13934-2, ASTM D5034, and GB/T 3932.2 (GB/T 3923.2), uses a wider specimen, typically 100 mm, of which only a central width (commonly 25 mm) is actually gripped by the jaws. This approach better reflects the performance of fabrics containing high-strength yarns that are prone to cutting or slipping in narrow clamps, and it is often preferred for heavy, coated, or strongly constructed fabrics. The gauge length is typically 100 mm with an extension rate of 50 mm/min.
Equipment and Test Procedure
Testing is conducted on a calibrated constant rate of extension (CRE) universal tensile testing machine equipped with pneumatic or mechanical grips and an appropriate force transducer, selected so that the anticipated breaking force falls within the calibrated range, ideally between 15 % and 85 % of full scale. The general procedure is as follows:
- Verify instrument calibration and select the force range appropriate to the expected breaking force
- Set the gauge length and extension rate according to the applicable standard
- Mount the conditioned specimen centrally in the jaws, aligned parallel to the direction of force application, applying the specified pretension where required
- Start the test and extend the specimen at constant rate until rupture occurs
- Record the maximum force and elongation values, discarding results from specimens that slip in the jaws or break within the jaw faces
- Repeat testing for the required number of specimens in each direction, typically at least five valid results per direction
- Calculate the arithmetic mean, coefficient of variation, and confidence interval for each direction
Expression of Results and Reporting
The final breaking strength is reported in newtons, rounded according to the requirements of the governing standard, together with the statistical summary and a full description of the test conditions. A complete report identifies the test method and standard used, specimen dimensions, gauge length, extension rate, conditioning atmosphere, number of specimens tested, and any anomalous failures. Comparisons against specification limits, such as minimum breaking force requirements in product standards or contractual agreements, are then performed to determine conformity.
Applications
Dry state breaking strength data supports decision-making across the entire textile value chain:
- Quality control during weaving, finishing, and dyeing to verify that mechanical properties meet internal and customer specifications
- Product development and comparative evaluation of new fibers, yarn counts, fabric constructions, and finishing recipes
- Compliance verification against national and international product standards for apparel, bed linen, and furnishing fabrics
- Assessment of degradation after treatments such as bleaching, mercerizing, resin finishing, or accelerated aging
- Input for technical textile design in geotextiles, filtration media, medical textiles, automotive textiles, and personal protective equipment
- Acceptance testing for incoming fabric lots and arbitration testing in commercial disputes, commonly performed by accredited third-party laboratories
- Support for eco-label and product certification schemes where minimum mechanical durability requirements apply
FAQ
What is the difference between dry and wet breaking strength?
Dry breaking strength is measured on specimens conditioned in a standard atmosphere, while wet breaking strength is measured on specimens fully soaked in water. Some fibers, notably cotton and other cellulosics, may gain strength when wet, whereas many regenerated and synthetic fibers lose strength. Comparing both values reveals how a fabric will perform in laundering or wet service conditions.
When should the grab method be used instead of the strip method?
The grab method is preferred for fabrics with high-strength yarns, dense constructions, or coatings that tend to slip, cut, or fray in narrow strip clamps. The strip method measures the strength of the full specimen width and is better suited to general-purpose woven fabrics and research comparisons.
How many specimens are required for a valid test?
Most standards require a minimum of five valid specimens per direction, with additional testing if specimens slip in the jaws or break at the jaw line. Results from invalid breaks are discarded and replaced so that the reported mean is statistically sound.
Why do specimens sometimes fail inside the jaw faces?
Jaw-line breaks occur when local stress concentration, excessive clamping pressure, or unsuitable jaw liners damage the specimen at the grip interface. They can be mitigated by adjusting clamping pressure, using padded or rubber-faced jaws, adding tab materials, or switching to the grab method.
What factors most commonly cause low breaking strength results?
Frequent causes include fiber degradation from over-bleaching or over-dyeing, weak or irregular yarn, low fabric cover factor, improper finishing chemistry, inadequate conditioning, and incorrect specimen width. Systematic investigation of raw materials, process records, and test conditions is recommended before drawing conclusions.
Which standards are most widely referenced for this test?
The most commonly cited methods are ISO 13934-1 and ISO 13934-2, EN ISO 13934-1 and EN ISO 13934-2, ASTM D5034 and ASTM D5035, and the Chinese national standards GB/T 3923.1 and GB/T 3923.2. All are equivalent in principle and rely on CRE tensile testers operated by trained personnel in controlled laboratory conditions.