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CAN CGSB 4.2 No. 10-M87 (2013): Breaking Strength of Fabrics – Grab Method
A Comprehensive Guide to the Canadian Standard for Tensile Testing of Textile Fabrics
Introduction
The Canadian General Standards Board (CGSB) standard CAN CGSB 4.2 No. 10-M87 (2013) specifies a method for determining the breaking strength and elongation of textile fabrics using the grab test procedure. As part of the CAN/CGSB-4.2 series of textile test methods, this standard is widely referenced in procurement specifications, quality assurance programs, and regulatory compliance across Canada and internationally. Reaffirmed in 2013, it remains a cornerstone for evaluating the tensile properties of woven, nonwoven, and knitted fabrics where the fabric construction or end-use does not require the strip test (CAN/CGSB-4.2 No. 9.2).
Key point: The grab method tests a wider fabric width (100 mm) with only the central 25 mm being stressed, simulating the resistance of a fabric to concentrated loads such as those encountered in seams or fasteners.
Scope
CAN CGSB 4.2 No. 10-M87 (2013) applies to most textile fabrics, including woven, nonwoven, and certain knitted materials. It is intended for use in acceptance testing of commercial shipments and for quality control in manufacturing. The standard covers:
- Measurement of maximum force (breaking strength) in the warp (lengthwise) and weft (widthwise) directions.
- Measurement of elongation at break, expressed as a percentage of the original gauge length.
- The grab test principle: only a portion of the specimen width is gripped, while the full width is present between the clamps.
The method is not suitable for fabrics that are highly extensible (e.g., elastic fabrics) or those that cannot be conditioned in a standard atmosphere. For such materials, alternative methods such as the strip test or the CRE (constant rate of extension) principle may be specified.
Limitation: Results obtained from the grab method are not directly comparable to those from the strip method (CAN/CGSB-4.2 No. 9.2) because the grab test engages fewer yarns and includes lateral constraint effects.
Technical Requirements
Test Specimen
Each specimen shall be 100 mm ± 2 mm wide and at least 150 mm long. The width is measured after conditioning in the standard atmosphere (20 °C ± 2 °C, 65 % ± 4 % relative humidity) for at least 24 hours. A minimum of five specimens per direction (warp and weft) is required, taken from different areas of the fabric to ensure representativeness.
Testing Machine
The tensiometer must operate on the constant rate of extension (CRE) principle, with a rate of traverse of 50 mm/min ± 5 mm/min. The force indicator shall have an accuracy of ±1 % of the indicated value or ±0.5 % of the full-scale load, whichever is greater. The gauge length (distance between clamps at the start) is set to 75 mm ± 1 mm.
Clamping and Gripping
The upper and lower clamps must have faces at least 25 mm wide and 50 mm high. The specimen is inserted such that only the central portion of the width (approximately 25 mm) is gripped by the clamp faces, while the outer edges remain free. This is the defining feature of the grab method.
Procedure Summary
- Condition specimens in the standard atmosphere for at least 24 hours.
- Mount the specimen centrally in the clamps, ensuring the outer edges are not gripped.
- Apply a pre-tension of 0.1 % of the expected breaking force (or a maximum of 2 N) to remove slack.
- Start the machine and record the maximum force and the elongation at break.
- Discard any results where the specimen slips in the clamps or breaks at the edge of the clamp face.
- Calculate the average breaking strength (in N or lbf) and the average elongation (in mm or %) for each direction.
Key Parameters Table
| Parameter | Value / Description |
|---|---|
| Specimen width | 100 ± 2 mm (full width) |
| Gripped width | Approx. 25 mm (central portion) |
| Gauge length | 75 ± 1 mm |
| Rate of extension | 50 ± 5 mm/min |
| Number of specimens per direction | Minimum 5 |
| Conditioning atmosphere | 20 ± 2 °C, 65 ± 4 % RH |
| Pre-tension | ≤ 2 N or 0.1 % of expected breaking force |
| Reporting units | Newtons (N) or pound-force (lbf); elongation in mm or % |
Implementation Highlights
Comparison with Strip Method (CAN/CGSB-4.2 No. 9.2)
The grab method differs from the strip method primarily in specimen gripping. In the strip test, the entire width (usually 50 mm) is held between the clamps, while the grab test holds only the centre 25 mm of a wider (100 mm) specimen. This makes the grab method more representative of in-service stresses where a fabric is loaded over a small area (e.g., at a button or seam). The grab test tends to yield higher breaking forces than the strip test for the same fabric because the unclamped outer edges contribute to lateral support and load distribution.
Typical Applications
- Quality control for woven apparel fabrics
- Acceptance testing for industrial textiles (e.g., tarpaulins, geotextiles)
- Verification of supplier specifications
- Benchmarking in research and development
Pro tip: Always condition specimens immediately before testing. Even a short exposure to ambient conditions can alter moisture content and significantly affect breaking strength results.
Compliance Notes
Standard Reaffirmation
CAN CGSB 4.2 No. 10 was originally published in 1987 and reaffirmed without technical changes in 2013. The current designation is CAN CGSB 4.2 No. 10-M87 (2013). While the core method remains unchanged, users should verify that no newer revisions or amendments have been issued by the CGSB. Compliance with the standard is typically specified in procurement contracts or referenced in technical regulations.
Laboratory Accreditation
Testing laboratories performing this method for regulatory or contractual purposes should be accredited to ISO/IEC 17025. Accreditation ensures that the laboratory follows the correct procedure, maintains appropriate equipment calibration, and participates in proficiency testing. Many jurisdictions require that textile product testing be carried out by an accredited laboratory using this standard.
Common Non‑conformities
- Incorrect gauge length or rate of extension.
- Specimens not conditioned for the required time.
- Use of worn or incorrectly sized clamp faces, leading to specimen slippage or premature jaw breaks.
- Failure to reject results from edge breaks or slip.
Critical compliance: If the breaking force difference between the five specimens in one direction exceeds 20 % of the average, the results may not be reliable. Additional specimens should be tested, and the cause of variation investigated.
Frequently Asked Questions
Q: What is the main difference between the grab method and the strip method in fabric tensile testing?
A: The grab method (CAN CGSB 4.2 No. 10) grips only the central 25 mm of a 100 mm wide specimen, leaving the outer edges free. The strip method (No. 9.2) grips the full specimen width (usually 50 mm). The grab method simulates localized loading and generally gives higher breaking strength values due to lateral support from the ungripped fabric.
A: The grab method (CAN CGSB 4.2 No. 10) grips only the central 25 mm of a 100 mm wide specimen, leaving the outer edges free. The strip method (No. 9.2) grips the full specimen width (usually 50 mm). The grab method simulates localized loading and generally gives higher breaking strength values due to lateral support from the ungripped fabric.
Q: Is CAN CGSB 4.2 No. 10-M87 (2013) still current?
A: Yes, the standard was reaffirmed in 2013 and continues to be the active version. Users should periodically check the CGSB website or the Canadian National Standards System (NSS) for any future reaffirmations or amendments.
A: Yes, the standard was reaffirmed in 2013 and continues to be the active version. Users should periodically check the CGSB website or the Canadian National Standards System (NSS) for any future reaffirmations or amendments.
Q: Can the grab method be used for knitted fabrics?
A: It can be used for some knitted structures, but caution is needed because high extensibility may cause the fabric to slip or distort in the clamps. The standard recommends evaluating on a case-by‑case basis and, if necessary, using a suitable strip or modified method.
A: It can be used for some knitted structures, but caution is needed because high extensibility may cause the fabric to slip or distort in the clamps. The standard recommends evaluating on a case-by‑case basis and, if necessary, using a suitable strip or modified method.
Q: What units are typically used for reporting?
A: The standard allows reporting in either newtons (N) or pound‑force (lbf). In Canadian and international contexts, SI units (N) are preferred. Elongation is reported as a percentage of the original gauge length or in millimetres.
A: The standard allows reporting in either newtons (N) or pound‑force (lbf). In Canadian and international contexts, SI units (N) are preferred. Elongation is reported as a percentage of the original gauge length or in millimetres.
© 2026 – This article is prepared for informational purposes. Always refer to the official standard document for complete and authoritative test procedures.