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CAN/CGSB-4.175-2013 Part 7: Flammability Testing of Textile Materials – A Technical Guide
Understanding the test methods, classification, and compliance requirements for textile flammability in Canada
Scope and Application
CAN/CGSB-4.175-2013 Part 7 is a National Standard of Canada that specifies a laboratory method for assessing the flammability of textile fabrics and flexible sheet materials. It is applicable to woven, knitted, nonwoven, tufted, and coated textiles intended for apparel, upholstery, bedding, curtains, and other consumer applications. The method evaluates ease of ignition, flame spread rate, afterflame, and afterglow characteristics under controlled conditions.
The standard excludes materials that melt or shrink away from the ignition source before burning (e.g., unsupported vinyl films) and those with very low weight per unit area that disintegrate; such products require alternative procedures from other parts of the CAN/CGSB-4.175 series.
Note: CAN/CGSB-4.175 is a multi-part standard. Part 7 focuses exclusively on flammability behaviour; other parts cover dimensional change, colourfastness, and strength tests.
Technical Requirements and Test Methods
Specimen Preparation and Conditioning
- Dimensions: Each specimen is cut to 150 mm × 50 mm, with directions marked (warp, weft, or as agreed).
- Number of specimens: A minimum of five per direction per sample is required.
- Conditioning: Specimens are conditioned for at least 24 hours at 21 ± 1 °C and 65 ± 2 % relative humidity before testing.
Apparatus
| Component | Specification |
|---|---|
| Test cabinet | Fully enclosed, ventilated with a draft screen, internal dimensions approximately 300 × 300 × 750 mm |
| Specimen holder | Capable of clamping the specimen at a 45° angle to the horizontal |
| Ignition source | Butane gas burner with a needle orifice producing a 16 mm total flame (10 mm inner cone) |
| Timing device | Stopwatch or electronic timer with 0.1 s resolution |
| Marking threads | At 13 mm and 140 mm from ignition end to define spread distance |
Testing Procedure
- The conditioned specimen is clamped in the holder and placed inside the cabinet.
- The ignition source is applied to the bottom edge or, for raised-fibre surfaces, to the face of the specimen. Contact time is normally 1 s for plain fabrics and 2–3 s for surface flash tests.
- Record the following:
– Ignition time: time to achieve sustained burning;
– Flame spread time: interval for flame to travel between the two marking threads (127 mm gap);
– Afterflame time: duration of burning after removal of the burner;
– Char length: length of material damaged by flame. - If the specimen fails to ignite, a fresh specimen must be tested with a longer contact time.
- The mean and range of flame spread times are calculated for each direction.
Flammability Classification
Materials are assigned a flammability class based on the average flame spread time and ignited specimen behaviour:
| Class | Description | Flame Spread Time (s) |
|---|---|---|
| 1 | Low flammability – self-extinguishing; suitable for most apparel | ≥ 7 |
| 2 | Intermediate flammability – requires careful end-use evaluation | 4 – 6.9 |
| 3 | High flammability – rapid and intense burning; restricted use | < 4 |
For raised-fibre surfaces, an additional surface flame test must be performed; the lower of the two results governs final classification.
Warning: Inadequate conditioning is the leading cause of non-reproducible results. Always verify that specimens are conditioned in a closed chamber and tested within 2 minutes of removal.
Implementation and Industry Impact
CAN/CGSB-4.175 Part 7 is widely referenced in Canadian regulations, including the Textile Flammability Regulations under the Canada Consumer Product Safety Act (CCPSA). Manufacturers of children’s sleepwear, mattresses, furniture, and theatrical curtains use it to ensure compliance with federal safety requirements.
Key implementation points:
- Testing should be performed in an ISO/IEC 17025 accredited laboratory to guarantee regulatory acceptance.
- Products that do not meet Class 1 criteria for a given application may still be marketed with proper hazard warnings (e.g., “Not for use in public occupancies”).
- The standard is harmonised with some international methods but differs in specimen orientation and ignition details; direct substitution of test results is not advisable.
Tip: Always cross-reference the latest version of the standard with provincial fire codes, as some jurisdictions impose stricter requirements than the national baseline.
Compliance and Certification Notes
To achieve compliance, a product’s documented test report must show that the average flame spread time meets the threshold for its intended end-use (typically Class 1 for general apparel). The complete report should include conditioning records, ignition times, afterflame times, and char measurements. Self-testing is permitted only if the laboratory complies with ISO/IEC 17025 and participates in proficiency testing.
Since the 2013 edition introduced changes to raised-surface specimen preparation and classification borderline definitions, users must ensure that outdated testing procedures are not used. The standard is maintained by CGSB; queries and interpretations can be requested through the committee secretariat.
Important: Products that fail to meet the required classification may be subject to recall, seizure, or import prohibition by the Canada Border Services Agency. Always engage a recognised testing body for certification.
Frequently Asked Questions
Q: Which material types are excluded from testing under CAN/CGSB-4.175 Part 7?
A: Materials that melt, shrink, or drip away from the flame before igniting (e.g., common unsupported vinyl or polyethylene films) and those below a mass per unit area of 60 g/m² are not covered by Part 7. Such textiles should be tested according to CAN/CGSB-4.175 Part 8 (for melting materials) or a separate standard.
A: Materials that melt, shrink, or drip away from the flame before igniting (e.g., common unsupported vinyl or polyethylene films) and those below a mass per unit area of 60 g/m² are not covered by Part 7. Such textiles should be tested according to CAN/CGSB-4.175 Part 8 (for melting materials) or a separate standard.
Q: How does this standard relate to the US federal CS 191-53 test?
A: Both test specimens at 45° and classify by flame spread time, but the CGSB standard uses a slightly different support frame and a 16 mm vs. 22 mm flame. Values are not directly interchangeable; conversion charts are available but not official.
A: Both test specimens at 45° and classify by flame spread time, but the CGSB standard uses a slightly different support frame and a 16 mm vs. 22 mm flame. Values are not directly interchangeable; conversion charts are available but not official.
Q: What is the frequency of testing required for ongoing production compliance?
A: While the standard itself does not specify audit intervals, regulatory programs often require testing at least every major production batch or change in raw material. A risk-based approach (e.g., lot-by-lot for high-risk items) is recommended.
A: While the standard itself does not specify audit intervals, regulatory programs often require testing at least every major production batch or change in raw material. A risk-based approach (e.g., lot-by-lot for high-risk items) is recommended.
Last updated March 2026