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CAN/CGSB 4.2 No. 56.1-M87 (2013): Vertical Flame Resistance Testing for Textiles
Understanding the Scope, Technical Requirements, and Compliance Criteria of the Canadian Standard for Textile Flammability
Scope and Application
CAN/CGSB 4.2 No. 56.1-M87 (2013) is the Canadian national standard that specifies a vertical flame resistance test method for textile materials. Published by the Canadian General Standards Board (CGSB) and reaffirmed in 2013, this standard is part of the comprehensive CAN/CGSB 4.2 series of textile test methods. It is primarily used to assess the response of textile fabrics, coatings, and assemblies when exposed to a small open flame under controlled laboratory conditions.
The method applies to woven, knitted, and nonwoven fabrics, including those with surface finishes or coatings, used in applications such as protective clothing, upholstery, curtains, and industrial textiles. It does not apply to textiles that are intended to be laundered or dry-cleaned repeatedly unless specifically noted, nor does it cover flame propagation over large surfaces or fire resistance of structural elements.
The standard is referenced in Canadian regulations for occupational health and safety, transportation, and consumer product safety. It is also used by manufacturers and laboratories to qualify materials for flame-retardant performance and to ensure consistency in quality control.
Technical Requirements
Test Specimen Preparation
Specimens are cut to a standard size of 70 mm × 300 mm. A minimum of five specimens in the warp (lengthwise) direction and five in the weft (crosswise) direction are required. Prior to testing, specimens are conditioned in an atmosphere of 21 ± 1 °C and 65 ± 2 % relative humidity for at least 24 hours. For materials that are sensitive to moisture, additional conditioning or a different atmosphere may be specified.
Apparatus and Ignition Source
The test chamber is a ventilated metal cabinet that shields the specimen from air drafts. The specimen is held vertically in a metal frame. The ignition source is a standardized methane gas burner with a flame height of 38 mm (measured from the tip of the burner). For most textile surfaces, the flame is applied to the lower edge of the specimen for 12 seconds. For raised-surface fabrics (e.g., pile, fleece, or napped fabrics), a shorter application of 3 seconds is used to avoid excessive melting or dripping that could invalidate the test.
Measurements and Criteria
After the ignition source is removed, the following parameters are recorded:
- Afterflame time (A): The duration in seconds for which the specimen continues to flame after removal of the burner.
- Afterglow time (G): The duration in seconds of glowing combustion after flaming ceases.
- Char length (L): The distance in millimetres from the bottom edge of the specimen to the top of the charred or melted area, measured after the specimen has cooled.
| Parameter | Requirement / Description |
|---|---|
| Specimen dimensions | 70 mm × 300 mm |
| Conditioning atmosphere | 21 ± 1 °C, 65 ± 2 % RH for ≥ 24 h |
| Burner gas | Methane (99 % minimum purity) |
| Flame height | 38 mm (1.5 in) |
| Flame application time (flat fabrics) | 12 s |
| Flame application time (raised surfaces) | 3 s |
| Number of specimens per direction | 5 (warp) + 5 (weft) |
| Recorded values | Afterflame time (s), afterglow time (s), char length (mm) |
Tip: Always verify that the specimen conditioning chamber is maintained within the specified tolerance. Out-of-tolerance humidity can significantly alter the flammability behaviour of many textiles, especially those containing cellulosic fibres.
Implementation Highlights
Test Setup and Calibration
To obtain reproducible results, the test cabinet must be level and free of air currents. The burner must be positioned so that the flame contacts the centre of the bottom edge of the specimen. Calibration of the flame height is performed using a jig or a ruler; any variation beyond ±2 mm may invalidate the test. The methane supply must be filtered and at a consistent pressure, typically 0.3 ± 0.05 bar at the burner inlet.
Acceptance Criteria
The standard does not prescribe pass/fail limits; these are typically established by product performance specifications or regulatory authorities. However, common industry practice for protective clothing applications, for example, often requires:
- Average afterflame time ≤ 2 s for any specimen
- Maximum afterflame time for any single specimen ≤ 10 s
- Average char length ≤ 150 mm
- No melting or dripping that ignites cotton batting placed below the specimen.
Users should consult the relevant regulatory standard (e.g., CSA Z96, NFPA 1971, or applicable building codes) for specific thresholds.
Caution: The vertical flame test is a small-scale flammability test and does not represent a large-scale fire scenario. A material that passes this test may still ignite in a real fire situation, especially if exposed to radiant heat or larger ignition sources.
Reporting
Each test report must include the standard designation, specimen identification, conditioning details, flame application time, and the individual and average values for afterflame time, afterglow time, and char length. Any anomalies (e.g., specimen shrinkage, tearing, or melting behaviour) should also be documented. The report must state whether the test was conducted on a fabric as received or after a specified number of cleaning cycles.
Compliance Notes
CAN/CGSB 4.2 No. 56.1-M87 (2013) is widely recognized by Canadian regulatory bodies for compliance with the Canada Consumer Product Safety Act (CCPSA) and various provincial fire codes. Textile products intended for sale in Canada are often required to meet the performance criteria referenced in this standard, particularly for:
- Protective clothing for industrial workers (e.g., welding, metallurgy, electrical utilities)
- Upholstery fabrics in public occupancies (e.g., hospitals, schools, theatres)
- Bedding and drapery in institutional settings
- Fabric components in motor vehicles and aircraft interiors (together with other applicable standards)
It is essential to note that the standard was reaffirmed in 2013 without modification. Laboratories accredited to ISO/IEC 17025 can include this test method in their scope of accreditation. The standard is harmonized with several international methods but differs in details such as specimen dimensions and flame application times from ASTM D6413 (USA) or ISO 6940 / ISO 6941 (international).
Compliance benefit: Testing to CAN/CGSB 4.2 No. 56.1-M87 reduces the risk of product liability claims, improves market access in Canada, and ensures a consistent level of flammability performance for end-users.
Important: Always ensure that the test is performed on representative production samples, including those that have undergone the expected number of laundering or cleaning cycles. Flame-retardant treatments may degrade over time, and a material that initially meets the criteria may fail after repeated cleaning.
Relationship with Other Standards
While CAN/CGSB 4.2 No. 56.1-M87 is similar in principle to ASTM D6413 (Standard Test Method for Flame Resistance of Textiles (Vertical Test)), there are notable differences in sample preparation and reporting format. ASTM D6413, for example, uses a 12-second application for all fabrics and a 100% polyester thread for tying, whereas the CGSB method may specify different tie materials. Organizations that trade internationally should be aware that Canada Customs or the UL Certification (Canada) may require direct compliance with the CGSB method rather than a foreign equivalent.
For materials that also require testing for resistance to radiant heat or large-flame exposure, additional standards such as CAN/CGSB 4.2 No. 57.1 or ISO 15025 (flame spread) may be referenced in combination with No. 56.1.
Frequently Asked Questions
Q: Is CAN/CGSB 4.2 No. 56.1-M87 mandatory for all textiles sold in Canada?
A: No, it is not mandatory for all textiles. However, its use is required or recommended in many federal and provincial safety regulations, especially for textiles used in protective clothing, public spaces, and transportation. Manufacturers should verify which standards are referenced in their specific product regulations.
A: No, it is not mandatory for all textiles. However, its use is required or recommended in many federal and provincial safety regulations, especially for textiles used in protective clothing, public spaces, and transportation. Manufacturers should verify which standards are referenced in their specific product regulations.
Q: What is the difference between the “12-second” and “3-second” flame application?
A: The 12-second application is the standard for most flat fabrics. The shortened 3-second application is used only for raised-surface fabrics (e.g., fleece, terry, pile) that may melt or shrink away from the flame quickly, causing a misleadingly long afterflame or a molten drip. Using the 12-second application on such fabrics would not provide an accurate assessment of their fire behaviour.
A: The 12-second application is the standard for most flat fabrics. The shortened 3-second application is used only for raised-surface fabrics (e.g., fleece, terry, pile) that may melt or shrink away from the flame quickly, causing a misleadingly long afterflame or a molten drip. Using the 12-second application on such fabrics would not provide an accurate assessment of their fire behaviour.
Q: Can the test be performed on finished products or only on fabric swatches?
A: The standard is intended for testing flat textile specimens. For finished products (e.g., garments, curtains, upholstered furniture), specimens should be cut from representative areas of the product. If the product has seams or multiple layers, separate tests on each layer may be required. The standard does not cover testing of assembled products, but the results from flat specimens are generally used to infer product compliance.
A: The standard is intended for testing flat textile specimens. For finished products (e.g., garments, curtains, upholstered furniture), specimens should be cut from representative areas of the product. If the product has seams or multiple layers, separate tests on each layer may be required. The standard does not cover testing of assembled products, but the results from flat specimens are generally used to infer product compliance.
Q: How often should the methane purity be checked?
A: Methane purity should be verified at least quarterly, or whenever a change in supply occurs. Contaminated or impure gas can affect flame temperature and height, leading to non-reproducible results. Using industrial-grade methane (≥99% purity) and a density-specific flow regulator is recommended.
A: Methane purity should be verified at least quarterly, or whenever a change in supply occurs. Contaminated or impure gas can affect flame temperature and height, leading to non-reproducible results. Using industrial-grade methane (≥99% purity) and a density-specific flow regulator is recommended.
— This article provides general guidance on the application of CAN/CGSB 4.2 No. 56.1-M87 (2013). For definitive interpretation, consult the official standard published by the Canadian General Standards Board. Last revised 2026.