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CAN CGSB 4.2 No. 8.3-M89 (2013): Tearing Strength of Textile Fabrics – Trapezoid Method
A Comprehensive Technical Guide to the Canadian Standard for Trapezoid Tearing Testing
Scope and Field of Application
CAN CGSB 4.2 No. 8.3-M89 (2013) is a test method developed by the Canadian General Standards Board (CGSB) to determine the tearing strength of textile fabrics using the trapezoid tearing procedure. The standard is part of the CAN/CGSB-4.2 series, which comprises uniform test methods for textile materials. Originally published in 1989 and reaffirmed in 2013, this method provides a reproducible and objective measure of a fabric’s resistance to tear propagation when a force is applied to a specially prepared trapezoid-shaped specimen.
The test method is applicable to woven, nonwoven, and felted fabrics, though it is primarily intended for woven textiles. It is widely used in textile quality control, material specification, and product certification programs within Canada. The results obtained using this method often serve as a basis for verifying performance claims and for conformity assessment under Canadian regulations.
Note: Compliance with CAN CGSB 4.2 No. 8.3-M89 (2013) is frequently required for textiles sold or used in Canada, particularly in sectors such as protective clothing, geotextiles, industrial fabrics, and home furnishings.
Technical Requirements
Apparatus
The test requires a constant-rate-of-extension (CRE) or constant-rate-of-traverse (CRT) tensile testing machine equipped with an appropriate load cell and clamps capable of gripping the specimen without slippage. The clamps must have faces at least 50 mm wide and be aligned to hold the specimen securely during the test. The machine must record the force continuously throughout the test with an accuracy of ±1% of the full-scale load.
Specimen Dimensions and Preparation
Each test specimen is cut to the dimensions shown in Table 1. The length direction of the specimen shall be parallel to either the warp (wale) or filling (course) direction, depending on the property of interest. At least five specimens per direction are tested. A small incision is made from the centre of the 50 mm side to initiate the tear.
| Parameter | Requirement |
|---|---|
| Total specimen length | 200 ± 1 mm |
| Total specimen width | 150 ± 1 mm |
| Length of parallel sides of trapezoid | 100 mm and 50 mm |
| Distance between trapezoid sides (perpendicular height) | 100 mm |
| Cut length (from 50 mm side toward 100 mm side) | 15 ± 0.5 mm |
| Gauge length (distance between clamp edges) | 100 mm |
| Rate of extension (CRE machine) | 300 ± 10 mm/min |
| Rate of traverse (CRT machine) | 300 ± 10 mm/min |
| Number of specimens per direction | At least 5 (warp/wale and filling/course) |
Conditioning
Specimens must be conditioned prior to testing in the standard atmosphere specified in CAN/CGSB-4.2 No. 2, i.e., 20 ± 2 °C and 65 ± 4 % relative humidity, for a minimum of 24 hours. The actual testing shall be conducted promptly after conditioning to avoid moisture re-equilibration.
Tip: For materials sensitive to moisture, such as cellulosic or polyamide fabrics, strict humidity control is essential. Even small deviations in RH can cause measurable changes in tear resistance.
Procedure
- Mount the specimen in the clamps so that the 100 mm side is in one clamp and the 50 mm side in the other, with the cut centred between the clamps and the specimen approximately parallel to the direction of force.
- Activate the tensile tester at the specified rate of extension or traverse.
- Allow the specimen to tear across the remaining width. Record the force required to propagate the tear. The tearing strength is taken as the average of the highest peaks observed during the tear propagation (typically over a defined region, e.g., the central portion of the tear).
- Discard any result where the tear deviates more than 10° from the intended direction, and test an additional specimen.
Caution: The trapezoid method may produce erroneous results with highly extensible fabrics (e.g., knits) because the initial incision may not propagate cleanly. For such materials, consider alternative methods such as the tongue tear (CAN/CGSB-4.2 No. 8.2) or the Elmendorf tear (CAN/CGSB-4.2 No. 8.1).
Calculation and Expression of Results
The individual tearing strengths are calculated as the arithmetic mean of the peak forces recorded for each valid specimen, expressed in newtons (N). The final result is the average of all individual values for each direction, reported separately for warp/wale and filling/course. If required, the coefficient of variation may also be calculated to assess precision.
Results should be rounded to the nearest 0.1 N. Test reports must include the number of specimens tested, conditioning details, and any deviations from the standard procedure.
Implementation and Practical Considerations
In a production environment, the trapezoid tear test is valued for its simplicity and relatively low consumption of fabric. However, operators must be trained to recognise improper tear paths and to ensure the machine is correctly set up. Regular calibration of the load cell and verification of the extension rate are mandatory for accredited laboratories.
The standard is harmonised with several international methods. For example, ASTM D4533 uses a similar trapezoid geometry but with different specimen dimensions and cut length; ISO 4674-2 describes a related method for coated fabrics. Laboratories that need to demonstrate equivalency between CAN CGSB 4.2 No. 8.3-M89 and these other methods must conduct a robust comparison study.
Critical: If the test machine is not calibrated regularly per CAN/CGSB-4.2 No. 0-series requirements, the measured tearing forces may be systematically inaccurate. This can lead to false passes or failures in product qualification and regulatory compliance.
Best Practice: Many Canadian buyers and specifiers explicitly call out CAN CGSB 4.2 No. 8.3-M89 in purchase orders. Demonstrating compliance with this standard can streamline market access and reduce the need for duplicate testing.
Compliance and Certification Notes
CAN CGSB 4.2 No. 8.3-M89 (2013) is maintained by the CGSB Committee on Textile Test Methods and is published in English and French. The “M89” in the designation indicates the original publication year (1989), and “2013” is the reaffirmation year. Although the technical content has not been revised, users should always check the CGSB website for any corrigenda or amendments that may have been issued.
For compliance with Canadian regulations (e.g., in personal protective equipment or children’s sleepwear), the test method must be followed without deviation. Third-party testing by laboratories accredited under ISO/IEC 17025 and listed with the Standards Council of Canada (SCC) is often required. The test report should clearly state the standard designation and the date of reaffirmation.
Q: What is the difference between the trapezoid tear test (No. 8.3) and the tongue tear test (No. 8.2)?
A: In the trapezoid test, a trapezoidal specimen is used and a small cut is made from the narrow side toward the wide side. The tear propagates across the entire width as the clamps separate. In the tongue tear test, a rectangular specimen is slit lengthwise to create two tongues, which are clamped in separate jaws so that the tear advances along the slit. The trapezoid method typically requires a simpler specimen preparation and is better suited for tightly woven fabrics, while the tongue method is often preferred for coated or laminated fabrics because it better simulates in-service damage.
A: In the trapezoid test, a trapezoidal specimen is used and a small cut is made from the narrow side toward the wide side. The tear propagates across the entire width as the clamps separate. In the tongue tear test, a rectangular specimen is slit lengthwise to create two tongues, which are clamped in separate jaws so that the tear advances along the slit. The trapezoid method typically requires a simpler specimen preparation and is better suited for tightly woven fabrics, while the tongue method is often preferred for coated or laminated fabrics because it better simulates in-service damage.
Q: Can this method be used for nonwoven fabrics?
A: Yes, CAN CGSB 4.2 No. 8.3-M89 is also applicable to nonwoven fabrics, provided they are sufficiently stable to be cut into the required trapezoid shape and the tear propagates in a consistent manner. For highly fibrous or stretchable nonwovens, alternative methods such as the trapezoid tear described in ASTM D5735 may be more appropriate. The specifier should indicate which standard is governing.
A: Yes, CAN CGSB 4.2 No. 8.3-M89 is also applicable to nonwoven fabrics, provided they are sufficiently stable to be cut into the required trapezoid shape and the tear propagates in a consistent manner. For highly fibrous or stretchable nonwovens, alternative methods such as the trapezoid tear described in ASTM D5735 may be more appropriate. The specifier should indicate which standard is governing.
Q: Is the standard still current? Was it updated in 2013?
A: The standard was reaffirmed in 2013 with no technical changes. It remains the active Canadian national standard for trapezoid tearing strength of textiles. Users should monitor the CGSB website for any future reaffirmations or revisions. Always confirm the latest status before specifying this test method in contracts or regulations.
A: The standard was reaffirmed in 2013 with no technical changes. It remains the active Canadian national standard for trapezoid tearing strength of textiles. Users should monitor the CGSB website for any future reaffirmations or revisions. Always confirm the latest status before specifying this test method in contracts or regulations.
Q: What are the typical units and reporting requirements?
A: The tearing strength is reported in newtons (N) for metric use or, in some historical contexts, in pounds-force (lbf). Modern practices require SI units. The test report must include the number of specimens tested in each direction and the calculated average tear strength, along with the conditioning parameters and any deviations. Statistical data such as standard deviation may also be provided.
A: The tearing strength is reported in newtons (N) for metric use or, in some historical contexts, in pounds-force (lbf). Modern practices require SI units. The test report must include the number of specimens tested in each direction and the calculated average tear strength, along with the conditioning parameters and any deviations. Statistical data such as standard deviation may also be provided.
Last updated January 2026. This article is for informational purposes and does not replace the official standard. Always refer to the latest version published by the Canadian General Standards Board.