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CAN CGSB 4.2 No. 9.5-M89 (2013) – Breaking Strength of Fabrics: The Strip Method for Textile Testing
A Technical Guide to the Canadian Standard for Determining Maximum Tensile Force in Woven and Nonwoven Fabrics by the Strip Test Procedure
Scope and Application
CAN CGSB 4.2 No. 9.5-M89 (2013) is a Canadian General Standards Board (CGSB) standard that specifies a test method for determining the breaking strength (maximum tensile force) of textile fabrics in the conditioned or wet state using the strip test principle. The method is primarily applicable to woven and nonwoven fabrics, including those with elastic properties, but excludes narrow fabrics (less than 100 mm wide) and industrial fabrics tested using specialized grips.
The strip method differs from the grab method in that the entire width of the specimen (normally 50 mm or 30 mm) is gripped in the clamps, ensuring that the fabric elements are uniformly loaded. This method is widely used in Canada for quality control, material acceptance, and research applications where the ‘true’ tensile behaviour of the fabric is required without edge effects. The standard is recognized as a mandatory reference in many procurement and regulatory documents for textile products sold in Canada.
Note: The standard was originally published in 1989 and reaffirmed in 2013 with minor editorial revisions. It remains current as of 2026 and is harmonized with international methods such as ISO 5081 and ASTM D5035, though specific conditioning and calculation differences exist.
Technical Requirements and Test Method
Specimen Preparation
The standard requires rectangular strips of fabric. For most woven fabrics, the width is 50 mm ± 1 mm, while for certain nonwoven or delicate fabrics, a width of 30 mm ± 1 mm may be used. The length must exceed the gauge length by at least 100 mm to allow proper clamping and pretension. A minimum of five specimens in the warp (machine) direction and five in the weft (cross) direction are required; for nonwoven materials, direction definitions follow the manufacturer’s designation.
Specimens must be cut with a sharp template or a cutting die to ensure parallel edges. Fraying at the edges may be controlled by using appropriate specimen widths that include frayed yarn allowance; usually fraying of loose yarns is acceptable except when the fabric is very loosely constructed, in which case the specimen width is measured after fraying.
| Parameter | Requirement (Conditioned Test) | Requirement (Wet Test) |
|---|---|---|
| Specimen width (woven) | 50 ± 1 mm | 50 ± 1 mm |
| Specimen width (nonwoven) | 30 ± 1 mm | 30 ± 1 mm |
| Gauge length | 200 ± 1 mm | 200 ± 1 mm |
| Rate of extension | 50 mm/min ± 10% | 50 mm/min ± 10% |
| Pre-tension | 0.5 N (or as agreed) | 0.5 N (or as agreed) |
| Minimum specimens per direction | 5 | 5 |
| Conditioning atmosphere | 20±2°C, 65±4% RH | Soak 1 h in 20±5°C distilled water |
Apparatus and Procedure
The tensile testing machine must be calibrated according to ISO 7500-1 Class 1 or equivalent. The constant-rate-of-extension (CRE) principle is used, with a movement rate of the pulling clamp of 50 mm/min ± 10%. The machine must record the maximum force (breaking strength) in newtons (N). A chart recorder or digital data system is acceptable.
Each conditioned specimen is mounted in the clamps with the specified pre-tension (0.5 N recommended). The specimen is then extended until rupture occurs. If a specimen breaks within 5 mm of the clamp edge, the result may be discarded and a retest performed on a new specimen. The breaking strength for each direction is reported as the arithmetic mean of the valid results, rounded to the nearest 1 N (or 0.1 N for values below 10 N).
Recommendation: When testing fabrics with high stretch (>20% elongation at break), ensure the extension rate and clamping pressure are adjusted to avoid slippage; rubber‑faced grips are often necessary.
Implementation Highlights
Laboratory Qualification
Testing laboratories seeking accreditation to CAN CGSB 4.2 No. 9.5-M89 must demonstrate proficiency through inter-laboratory comparisons. Key implementation aspects include:
- Conditioning: Fabrics must be conditioned in the standard atmosphere for at least 24 hours before testing, and the test itself should be conducted in the same environment unless the wet test is specified.
- Calibration: Force and elongation measurements must be traceable to national standards. Annual calibration of the testing machine is mandatory.
- Data reporting: Individual and mean results are recorded. The standard deviation and coefficient of variation should be calculated for each set of specimens to assess test precision.
Important: The strip method is sensitive to specimen alignment. Misalignment (skewed clamping) can cause premature failure at the clamp edge, leading to underestimated breaking strength. Use of alignment guides is strongly recommended.
Comparison with Other Methods
While the strip method often yields higher strength values than the grab method (since more yarns are loaded simultaneously), the choice between test methods depends on the end-use application. CAN CGSB 4.2 No. 9.5-M89 is preferred when the fabric will be subjected to uniform tensile loading across its width (e.g., conveyor belts, parachute webbing). The standard also provides guidance for ‘ravelled strip’ testing where edge yarns are removed to create a precise width, minimising edge effects.
Compliance Notes
Regulatory and Contractual Use
The standard is referenced in the Textile Labelling Act (Canada) for performance claims related to breaking strength. Manufacturers must ensure that fabrics advertised as “high‑strength” meet the minimum values established using this method. Contracts between suppliers and purchasers often specify CAN CGSB 4.2 No. 9.5-M89 as the method for acceptance testing. Discrepancies in test results can be resolved by arbitration testing at an accredited laboratory.
Common Non‑Compliances
Frequent findings during audits include:
- Use of incorrect specimen width (e.g., 30 mm for woven fabrics without justification).
- Failure to conduct wet tests when the product may be exposed to moisture during its lifecycle.
- Insufficient number of replicates (less than five per direction).
- Not recording the exact breaking location (edge breaks must be reported).
Critical: Using an extension rate other than 50 mm/min without documented justification invalidates the test. The standard does not permit alternative rates unless agreed upon in the product specification.
To maintain compliance, laboratories must follow the standard precisely, including any amendments or errata. The 2013 reaffirmation did not alter technical content but clarified the calculation of wet test conditioning time.
Frequently Asked Questions
Q: Can this standard be used for knitted fabrics?
A: CAN CGSB 4.2 No. 9.5-M89 is primarily designed for woven and nonwoven fabrics. For knitted fabrics, a different method (such as the grab method or a loop test) is typically recommended because the strip method may produce high variation due to fabric structure and edge curling. However, if the specification calls for it, the strip method can be used on knits with caution—report all anomalies.
A: CAN CGSB 4.2 No. 9.5-M89 is primarily designed for woven and nonwoven fabrics. For knitted fabrics, a different method (such as the grab method or a loop test) is typically recommended because the strip method may produce high variation due to fabric structure and edge curling. However, if the specification calls for it, the strip method can be used on knits with caution—report all anomalies.
Q: What is the difference between the strip method and the grab method?
A: In the strip method, the entire width of the specimen is clamped (e.g., 50 mm), exerting tensile force on all yarns in that width. In the grab method, only the central portion of the fabric is gripped, leaving the edges free. The strip method generally gives higher breaking strength and less variation because it eliminates edge effects, but it requires more fabric and is less representative of actual seam loading in apparel.
A: In the strip method, the entire width of the specimen is clamped (e.g., 50 mm), exerting tensile force on all yarns in that width. In the grab method, only the central portion of the fabric is gripped, leaving the edges free. The strip method generally gives higher breaking strength and less variation because it eliminates edge effects, but it requires more fabric and is less representative of actual seam loading in apparel.
Q: Is there a conversion factor between breaking strength measured by CAN CGSB 4.2 No. 9.5-M89 and values reported per ISO 5081?
A: No universal conversion factor exists because differences in specimen width (50 mm vs. 30 mm), conditioning, and calculation methods (incl. SI vs. non‑SI units) can affect results. However, when identical test conditions are applied (same width, same conditioning), the two standards are expected to yield comparable results. It is always recommended to test using the exact method specified in the contract or regulation.
A: No universal conversion factor exists because differences in specimen width (50 mm vs. 30 mm), conditioning, and calculation methods (incl. SI vs. non‑SI units) can affect results. However, when identical test conditions are applied (same width, same conditioning), the two standards are expected to yield comparable results. It is always recommended to test using the exact method specified in the contract or regulation.
Standard reference: CAN CGSB 4.2 No. 9.5-M89 (2013)
Copyright: Canadian General Standards Board – This article is for informational purposes only. Always refer to the latest official version of the standard.
Year: 2026