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CAN CGSB 4.160-75 (2013): Tearing Strength of Textile Fabrics — Falling Pendulum (Elmendorf) Method
A comprehensive guide to the Canadian standard for determining the tear resistance of woven and nonwoven fabrics using the Elmendorf apparatus
The standard CAN CGSB 4.160-75 (2013) — reaffirmed by the Canadian General Standards Board in 2013 — provides a definitive method for determining the tearing strength of textile fabrics using the falling pendulum (Elmendorf) apparatus. This test is critical for evaluating the resistance of fabrics to the propagation of a single-rip tear, a property essential for applications in protective clothing, upholstery, industrial textiles, and other technical fabrics. The method is widely adopted by textile laboratories across Canada and recognized internationally for its reproducibility and simplicity.
Scope and Application
This standard specifies a procedure for measuring the tear strength of most woven and nonwoven textile fabrics. The test is applicable to fabrics that are stable enough to allow a clean tear propagation and excludes highly extensible knitted fabrics or those that exhibit plastic deformation during the tearing process. The method is designed for use in quality control, material specification verification, and research and development contexts. It is referenced by numerous downstream product standards, including those for protective clothing (e.g., CAN/CGSB 155.1) and geotextiles (e.g., CAN/CGSB 148.1).
The test principle involves a pendulum that falls from a fixed starting height, tearing the test specimen which is clamped between the pendulum and a stationary clamp. The energy absorbed in tearing the fabric reduces the pendulum’s subsequent rise, and the scale reading (in grams-force or millinewtons) directly indicates the average tearing force. The standard details each element of the method to ensure consistent results across different laboratories.
Technical Requirements and Test Method
Apparatus
The core instrument is the Elmendorf tear tester, equipped with a sector-shaped pendulum carrying a clamping jaw. The apparatus must include a stationary clamp mounted on the tester frame, a mechanism for releasing the pendulum from a predetermined angular position, and a scale that records the tearing force in the appropriate units. Pendulum capacities are selected based on fabric type; common capacities range from 400 gf (3.92 N) to 6400 gf (62.8 N). The standard requires that the tester be calibrated at least once every 12 months using certified reference masses and that daily verification checks be performed.
Test Specimens
Specimens are cut to standard dimensions: 100 mm ± 1 mm in length and 75 mm ± 1 mm in width. A 20 mm ± 1 mm precut slit is made from the center of the short side toward the opposite edge, creating two tabs for clamping. For woven fabrics, specimens are cut separately in the warp (longitudinal) and weft (transverse) directions; for nonwovens, in the machine direction (MD) and cross direction (CD). The number of specimens per direction is as follows:
| Fabric Type | Direction | Number of Specimens | Conditioning |
|---|---|---|---|
| Woven | Warp / Weft | 5 per direction | Standard atmosphere (20 ± 2 °C, 65 ± 4 % RH) for 24 h |
| Nonwoven | MD / CD | 5 per direction | Standard atmosphere for 24 h |
All specimens must be conditioned in the standard atmosphere for textile testing (20 °C ± 2 °C and 65 % ± 4 % relative humidity) for a minimum of 24 hours prior to testing. The standard also specifies that no two specimens in the same direction contain the same warp or weft yarns to ensure representative sampling.
Procedure
The conditioned specimen is mounted with the slit aligned vertically and the two tabs clamped into the stationary and pendulum jaws respectively. The pendulum is released, and the tear propagates across the width of the specimen. The maximum scale reading at the moment of full tear is recorded. For each direction, the average tear strength (in grams-force or millinewtons) is calculated from the individual readings, and the coefficient of variation is reported. If any specimen tears at the clamp edge or exhibits anomalous elongation, the result is discarded and an additional specimen tested.
Tip: Verify the pendulum friction daily using a friction-checking template provided by the instrument manufacturer. Even small increases in friction can lead to significant underestimation of tear strength.
Warning: When cutting the initial 20 mm slit, use a sharp template and a single smooth cutting motion. Jagged or angled slits can cause premature tearing or skewed propagation, invalidating the test.
Implementation Highlights
Implementing CAN CGSB 4.160-75 (2013) in a testing laboratory requires careful attention to apparatus maintenance and operator training. Key implementation tips include:
- Choose the correct pendulum capacity: As a rule of thumb, select a capacity such that the tearing force falls between 20 % and 80 % of the scale. Using a capacity that is too high reduces resolution; too low may cause the pendulum to go past the full-stop position.
- Monitor clamp pressure: Both the stationary and pendulum clamps must provide uniform, reproducible pressure to avoid slippage. Clamp faces should be cleaned regularly and replaced when worn.
- Conduct periodic interlaboratory comparisons: Participate in proficiency testing programs (e.g., those organized by CGSB or ASTM) to ensure your results are consistent with other accredited laboratories.
Success: Laboratories that implement this standard in conjunction with ISO/IEC 17025 accreditation demonstrate reliable tear strength data that meets the requirements of major buyers and regulatory bodies.
Compliance and Quality Assurance Considerations
Compliance with CAN CGSB 4.160-75 (2013) is often mandated in contracts for textile products supplied to Canadian federal departments (such as Public Services and Procurement Canada) and in general industrial procurement. To demonstrate compliance, a laboratory must:
- Maintain the Elmendorf tester in calibrated condition with records traceable to the National Research Council of Canada (NRC) or equivalent.
- Retain detailed test reports that include specimen identification, conditioning duration, pendulum capacity, individual tearing forces, averages, and coefficients of variation.
- Follow the standard’s prescribed sampling plan — at minimum, five specimens per direction — and document any deviations.
The standard also includes informative notes on precision and bias, referencing interlaboratory studies that provide repeatability (r) and reproducibility (R) limits. These limits are useful for interpreting differences between test results.
Danger: Never handle conditioned specimens with bare hands. Oil and moisture from skin can significantly alter tear propagation, leading to non‑representative results. Use lint‑free gloves or tweezers at all times.
Frequently Asked Questions
Q: What is the principle of the Elmendorf tear test?
A: The test measures the energy required to propagate a tear through a fabric specimen. A pendulum of known mass falls from a fixed height, and the reduction in its kinetic energy after tearing the fabric is directly related to the average tearing force. The scale reading is calibrated to show the tearing force in grams-force or millinewtons.
A: The test measures the energy required to propagate a tear through a fabric specimen. A pendulum of known mass falls from a fixed height, and the reduction in its kinetic energy after tearing the fabric is directly related to the average tearing force. The scale reading is calibrated to show the tearing force in grams-force or millinewtons.
Q: What types of fabrics are excluded from this standard?
A: The method is not suitable for highly stretchable knitted fabrics, elastic woven fabrics, or materials that undergo plastic deformation during tearing. For those materials, alternative test methods such as the trapezoidal tear or the double‑rip tear may be more appropriate.
A: The method is not suitable for highly stretchable knitted fabrics, elastic woven fabrics, or materials that undergo plastic deformation during tearing. For those materials, alternative test methods such as the trapezoidal tear or the double‑rip tear may be more appropriate.
Q: How many test specimens are required for a complete evaluation?
A: The standard requires a minimum of five specimens per test direction (warp and weft for wovens; machine and cross direction for nonwovens), giving a total of ten specimens per fabric. Additional specimens may be tested if the coefficient of variation exceeds 15 % or if any result is discarded due to anomalous failure.
A: The standard requires a minimum of five specimens per test direction (warp and weft for wovens; machine and cross direction for nonwovens), giving a total of ten specimens per fabric. Additional specimens may be tested if the coefficient of variation exceeds 15 % or if any result is discarded due to anomalous failure.
Q: Why was the standard reaffirmed in 2013 rather than revised?
A: The technical committee determined that the existing test method remains technically valid and consistent with current industry practice and international standards (e.g., ASTM D1424, ISO 1974). No substantive changes were required, so the standard was reaffirmed to maintain its availability for regulatory and contractual reference.
A: The technical committee determined that the existing test method remains technically valid and consistent with current industry practice and international standards (e.g., ASTM D1424, ISO 1974). No substantive changes were required, so the standard was reaffirmed to maintain its availability for regulatory and contractual reference.
© 2026 Canadian General Standards Board. All rights reserved. This article is for informational purposes and does not replace the official standard document.