CAN CGSB 4.2 No. 8.1-M89 (2013): Breaking Strength of Textile Fabrics – Strip Method – Comprehensive Technical Analysis

Scope and Purpose

CAN CGSB 4.2 No. 8.1-M89 (2013) is a Canadian national standard that specifies a strip method for determining the breaking strength (maximum force) and elongation at break of textile fabrics. The method is intended for woven, nonwoven, felted, and knitted fabrics (where applicable) and is widely used in quality control, product certification, and material acceptance testing. The strip method (also known as the cut-strip method) differs from the grab method in that the specimen is cut to a specified width and frayed (ravelled) to a defined number of yarns, ensuring that all yarns in the test area are engaged during the tensile test.

This standard is part of the CAN/CGSB 4.2 series of textile test methods published by the Canadian General Standards Board (CGSB). The 2013 reaffirmation confirms that the technical content of the 1989 edition has been reviewed and remains current. It is harmonized with ASTM D5035 (Strip Method) and ISO 13934-1 (Strip Method) in many respects, though differences exist in conditioning, specimen dimensions, and calculation procedures.

Technical Requirements

Apparatus

• Tensile testing machine: Constant-rate-of-extension (CRE) or constant-rate-of-traverse (CRT) types are permitted. The machine must be capable of maintaining a specified rate of extension (usually 300 ± 10 mm/min) and recording force with an accuracy of ±1% of the indicated value.
• Clamps: Flat, smooth-faced clamps with a minimum width of 50 mm (2 in.) are required. The front clamp (moving) should be wider than the specimen to prevent edge damage. Clamp face size and gripping pressure must be sufficient to prevent slippage without causing jaw breaks.
• Cutting template or cutter: For preparing strips of exact width, typically 50 mm (2 in.) or 25 mm (1 in.) depending on fabric type.
• Fraying device (optional): A comb or pointed instrument to remove yarns from the specimen edges to reach the specified number of yarns.
• Conditioning chamber: Standard atmosphere for textile testing (20 ± 2 °C, 65 ± 4% RH).

Test Specimens

Specimens are cut in the warp (lengthwise) and weft (crosswise) directions. The number of specimens per direction is usually 5, or as specified in the material specification. Two specimen types are allowed:

Note: For fabrics where fraying would cause damage (e.g., coated or fused fabrics), the standard allows testing without fraying, but the specimen width must be measured exactly before test.

Conditioning and Atmosphere

All specimens must be conditioned for a minimum of 24 hours in the standard atmosphere (20 ± 2 °C, 65 ± 4% RH) before testing. The standard does not permit testing under ambient conditions unless the material specification explicitly allows it.

Procedure

1. Select specimens from a representative sample, avoiding folds, creases, or warp distortions.
2. Cut specimens to the required length (≥ 150 mm for Type I).
3. For Type I, fray the edges by removing complete yarns until exactly 50 yarns remain (or the nearest number to achieve the specified width). For Type II, reduce to 25 yarns.
4. Mount the specimen centrally in the jaws with an initial gauge length of 75 mm.
5. Apply a pre-tension load as specified (usually 0.5% of expected breaking load, max 5 N) to remove slack.
6. Start the tensile machine at 300 ± 10 mm/min and record the maximum force and elongation at break.
7. Report the average breaking force (N) and average elongation at break (mm or %) for each direction separately.

Calculation and Expression of Results

The breaking strength is expressed as the force in newtons (N) required to break the specimen. Elongation may be reported as absolute extension (mm) or as a percentage relative to the original gauge length. Results for warp and weft are reported separately. The report must also include the number of specimens, any deviations from the standard, and details of conditioning.

Implementation Highlights

When implementing CAN CGSB 4.2 No. 8.1-M89 (2013) in a laboratory setting, the following points are critical:

• Harmonization with other standards: While the strip method is similar in principle to ASTM D5035 and ISO 13934-1, differences exist in gauge length (75 mm vs. 200 mm in ISO for some fabrics) and in the fraying requirement (ASTM often uses a nominal cut width without counting yarns). Laboratories that test to multiple standards must ensure method-specific validation.
• Calibration and verification: The tensile tester must be calibrated at least annually, and daily verification with a certified weight or load cell should be performed. Jaw alignment and speed must be checked per manufacturer instructions.
• Sample rotation: To avoid directional bias, specimens from different areas of the fabric should be rotated. For narrow fabric testing (Type II), sampling from the roll width is especially important.
• Data interpretation for acceptance: Many Canadian procurement documents set minimum breaking strength values for warp and weft based on this standard. For example, a heavy-duty workwear fabric may require ≥ 800 N in warp and ≥ 400 N in weft.

Compliance Notes

Compliance with CAN CGSB 4.2 No. 8.1-M89 (2013) is mandated when referenced in Canadian federal procurement contracts, safety regulations, or product standards (e.g., for personal protective equipment, firefighter clothing, or military textiles). Third-party testing by an accredited laboratory is often required.

Key compliance considerations include:

• Accreditation: Laboratories must be accredited to ISO/IEC 17025 by a recognized body (e.g., SCC, A2LA, or UKAS). The standard must be included in the accredited scope.
• Measurement uncertainty: The laboratory must estimate and report measurement uncertainty for breaking force and elongation, typically using a bottom-up approach (e.g., GUM method) or interlaboratory data. This is especially important for regulatory limits.
• Quality control samples: Use of control fabrics of known breaking strength should be run daily or weekly to check consistency; Shewhart control charts are recommended.
• Method modifications: Any deviation from the standard (e.g., different gauge length, non-standard temperature/humidity, or use of a different tester type) must be documented and justified; the client must be informed, and the report must note the deviation.

Frequently Asked Questions

Last updated: 2026. This article is prepared for informational purposes based on the published CAN CGSB 4.2 No. 8.1-M89 (2013) standard. For official compliance, always refer to the current version from the Canadian General Standards Board.