Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
CAN CGSB 4.2 No. 23-M90 (2013): Standard Test Method for Breaking Strength of Textile Fabrics – Grab Method
A comprehensive overview of the Canadian standard for assessing tensile properties of woven and nonwoven fabrics using the grab test procedure
Scope
CAN CGSB 4.2 No. 23-M90 (2013) establishes a standardised procedure for determining the breaking strength and elongation of textile fabrics using the grab method. This method is primarily intended for woven fabrics, but it may also be applied to nonwoven or knitted structures where the fabric construction allows the grab test to produce meaningful results. The standard is part of the Canadian General Standards Board (CGSB) series on textile test methods.
The grab method differs from the strip method (CGSB 4.2 No. 22) in that the specimen is clamped only in the central portion of its width, thereby involving more fabric structure in the test and providing a better measure of the “in-use” breaking strength. The method is applicable to most textile fabrics that can be held in a tensile testing machine, including those with finishes, coatings, or other treatments.
The standard was originally published in 1990 and reaffirmed in 2013 with minor editorial updates, ensuring its continued relevance in the Canadian textile industry.
Technical Requirements
Apparatus
- Tensile testing machine: Constant-rate-of-extension (CRE) type, capable of maintaining a constant rate of extension of 300 ± 10 mm/min (12 ± 0.5 in/min). The machine must have a recording device to plot force vs. elongation.
- Jaws: Two clamping faces, each 25.4 mm × 25.4 mm (1 in × 1 in). The jaws must be smooth-faced, without scoring, to avoid damaging the specimen. The front edge of each jaw must be precisely aligned.
- Specimen cutter: Template or die to cut specimens exactly 100 mm wide by 150 mm long (4 in × 6 in).
Specimen Preparation
- Cut a minimum of five specimens in the warp (machine) direction and five in the weft (cross) direction.
- Specimens shall be cut with the longer dimension parallel to the direction being tested.
- Condition specimens in a standard atmosphere of 21 ± 1°C and 65 ± 2% relative humidity for at least 24 hours prior to testing.
- Specimens must be free of creases, wrinkles, or off-grain distortions.
Test Procedure
- Mount the specimen centrally between the jaws with the long edges parallel to the direction of pull. The jaws clamp only the central 25 mm of the specimen width, leaving the edges free.
- Apply a pre-tension of approximately 10 N or enough to straighten the fabric without loading it significantly.
- Start the test machine and apply the tensile force at the specified rate until the specimen breaks.
- Record the maximum force (breaking load) in newtons (N) or kilograms-force (kgf). Record the elongation at break to the nearest millimetre.
- Discard any results where the break occurs at the edge of the jaws (jaw break) – at least five valid breaks are required per direction.
| Parameter | Value |
|---|---|
| Specimen size (width × length) | 100 mm × 150 mm (4 in × 6 in) |
| Jaw clamping area | 25.4 mm × 25.4 mm (1 in × 1 in) |
| Gauge length (distance between jaws) | 75 mm (3 in) |
| Rate of extension | 300 mm/min ± 10 mm/min (12 in/min ± 0.5 in/min) |
| Number of specimens (per direction) | Minimum 5 valid breaks |
| Pre-tension | ~10 N (enough to straighten fabric) |
| Conditioning atmosphere | 21 ± 1 °C, 65 ± 2 % RH, ≥ 24 h |
Implementation Highlights
Alignment and Jaw Grip
Proper alignment of the jaws is critical to avoid off-angle pulls that can cause premature jaw breaks or skewed force readings. The flat surfaces of the jaws must be parallel and squarely aligned relative to the line of pull. Check alignment using a machinist’s square before each series of tests.
Warning: Off-grain specimens can lead to highly variable results. Always ensure the specimen is cut and mounted with the warp or weft yarns parallel to the direction of force.
Conditioning
Because textile breaking strength is highly sensitive to moisture and temperature, strict adherence to the standard conditioning atmosphere is essential. Laboratories should monitor and record prevailing conditions during testing. Even short exposures outside the standard environment can change fibre properties, especially in moisture‑sensitive materials like cotton or rayon.
Tip: Use a humidity‑controlled chamber or a conditioning rack with air circulation to ensure all specimens equilibrate uniformly.
Test Speed Verification
The constant‑rate‑of‑extension (CRE) machine must be verified periodically to confirm the crosshead speed is maintained within ±10 mm/min at the specified 300 mm/min. If the machine is used for other methods requiring different speeds, a thorough verification of speed accuracy should be performed before testing per No. 23-M90.
Calculation of Results
Report the mean breaking strength (in N) separately for warp and weft directions, along with the standard deviation and coefficient of variation. The elongation at break is normally reported as the percentage increase in gauge length at the moment of rupture. If five or more specimens are tested, the median may also be reported when outliers are present.
Good practice: CAN CGSB 4.2 No. 23-M90 is technically equivalent to ASTM D5034, which facilitates acceptance of results between Canadian and U.S. markets.
Compliance Notes
Conformance with the Standard
To claim conformance with CAN CGSB 4.2 No. 23-M90 (2013), all aspects of the procedure must be strictly followed, including specimen conditioning, jaw alignment, rate of extension, and reporting. Deviations, such as using a different jaw size or a faster extension rate, void the conformance claim.
Critical: Non‑standard jaw faces (e.g., serrated or rubber‑coated) can alter the grip behaviour and produce results that are not comparable with those obtained in inter‑laboratory studies.
Precision and Bias
The standard provides a precision statement based on an inter‑laboratory study conducted during the original development. For woven fabrics, within‑laboratory coefficients of variation typically range from 3% to 8%, while between‑laboratory variations may be up to 15%. Laboratories are encouraged to participate in proficiency testing to benchmark their performance.
Quality Assurance
For routine quality control, the standard recommends testing per production lot (e.g., one specimen direction per roll) and comparing results with material specifications. When disputes arise, the referee procedure of the standard – involving an increased number of specimens and careful outlier handling – shall be used.
Frequently Asked Questions
Q: Can CAN CGSB 4.2 No. 23-M90 be used for knitted fabrics?
A: The method was primarily designed for woven fabrics. For knits, the grab test may still be applicable if the fabric can be clamped without distortion and the break occurs within the gauge length. However, results may show higher variability, and a different standard (e.g., CAN/CGSB 4.2 No. 21 Strip Test) may be more appropriate.
A: The method was primarily designed for woven fabrics. For knits, the grab test may still be applicable if the fabric can be clamped without distortion and the break occurs within the gauge length. However, results may show higher variability, and a different standard (e.g., CAN/CGSB 4.2 No. 21 Strip Test) may be more appropriate.
Q: How does this standard differ from ASTM D5034?
A: CAN CGSB 4.2 No. 23-M90 and ASTM D5034 are technically equivalent in terms of specimen size, jaw dimensions, gauge length, and rate of extension. Differences are mainly in formatting and national references. A fabric tested under one standard should produce comparable results under the other, provided conditioning and equipment are identical.
A: CAN CGSB 4.2 No. 23-M90 and ASTM D5034 are technically equivalent in terms of specimen size, jaw dimensions, gauge length, and rate of extension. Differences are mainly in formatting and national references. A fabric tested under one standard should produce comparable results under the other, provided conditioning and equipment are identical.
Q: Why is the grab method preferred over the strip method for some fabrics?
A: The grab method clamps only the central portion of the specimen, leaving the edges free. This better simulates the stress distribution a fabric experiences during actual use (e.g., at seams or in tension). It also avoids edge‑damage effects and is often easier to perform on heavy or coated fabrics.
A: The grab method clamps only the central portion of the specimen, leaving the edges free. This better simulates the stress distribution a fabric experiences during actual use (e.g., at seams or in tension). It also avoids edge‑damage effects and is often easier to perform on heavy or coated fabrics.
Q: What are the consequences of not conditioning specimens properly?
A: Failure to condition specimens to the specified atmosphere (21 ± 1 °C, 65 ± 2 % RH) will lead to moisture‑dependent changes in fibre properties. For hygroscopic fibres like cotton, a difference of 5% RH can alter breaking strength by 5‑10%, making results non‑repeatable and non‑compliant with the standard.
A: Failure to condition specimens to the specified atmosphere (21 ± 1 °C, 65 ± 2 % RH) will lead to moisture‑dependent changes in fibre properties. For hygroscopic fibres like cotton, a difference of 5% RH can alter breaking strength by 5‑10%, making results non‑repeatable and non‑compliant with the standard.
© 2026 Technical Article on CAN CGSB 4.2 No. 23-M90 (2013). This article is provided for informational purposes and does not replace the official standard document.