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CAN CGSB 4.2 No. 39-2004 (2013): Standard Test Method for Resistance of Textile Fabrics to Weathering
A Comprehensive Guide to Evaluating Textile Durability Under Natural and Accelerated Weathering Conditions
Scope and Purpose
CAN CGSB 4.2 No. 39-2004 (2013) is a Canadian standard developed by the Canadian General Standards Board (CGSB) within the CGSB 4.2 series of textile test methods. This standard specifies a procedure for determining the resistance of textile fabrics to weathering, including the effects of sunlight, temperature, moisture, and atmospheric contaminants. The test method is applicable to a wide range of textile materials, including woven, knitted, and nonwoven fabrics, as well as coated or laminated textiles. The standard provides two exposure options: natural outdoor weathering (at specified exposure sites) and laboratory-controlled accelerated weathering using xenon-arc or fluorescent UV apparatus. The primary purpose is to assess changes in physical properties such as breaking strength, colour change, and dimensional stability after defined exposure periods.
Technical Requirements
Specimen Preparation and Sampling
The standard requires that test specimens be representative of the material as supplied. For each exposure condition, a minimum of five specimens cut in the warp and weft directions are specified. Specimen dimensions are typically 50 mm x 200 mm, but the standard permits adaptations based on fabric structure. Samples must be conditioned at 20 ± 2 °C and 65 ± 4 % relative humidity for at least 24 hours before initial testing. A set of control specimens is retained in a dark, dry environment for comparison.
Exposure Conditions
Two methods are described:
- Method A – Natural Weathering: Specimens are mounted on exposure racks inclined at 45° facing south (in the Northern Hemisphere) at a CGSB‑approved site. Exposure continues for a fixed period (commonly 30, 60, 90, or 180 days) or until a predetermined amount of degradation is observed. Irradiance, temperature, and rainfall are recorded.
- Method B – Accelerated Weathering: Uses a xenon-arc lamp filtered to simulate sunlight (e.g., daylight filter) with a specified irradiance (0.35 W/m² at 340 nm) and a cycle of light and spray. The standard cycle includes 102 minutes of light followed by 18 minutes of light and spray, at a black-panel temperature of 63 °C ± 2 °C. Exposure duration is defined in hours (e.g., 100, 200, 400 h) or based on a specific radiant exposure (kJ/m² at 340 nm).
Parameter Table
| Parameter | Requirement (Method B) |
|---|---|
| Light source | Xenon-arc with daylight filter |
| Irradiance (340 nm) | 0.35 W/m² |
| Black-panel temperature | 63 °C ± 2 °C |
| Relative humidity | 50 % ± 5 % |
| Light cycle | 102 min light only |
| Spray cycle | 18 min light + spray |
| Exposure duration | Specified in h or kJ/m² |
Implementation Highlights
Proper execution of CAN CGSB 4.2 No. 39-2004 (2013) requires careful attention to mounting methods (specimens must be under light tension without distortion), periodic rotation of specimens within the exposure chamber to ensure uniform irradiance, and simultaneous exposure of a reference material (e.g., a standard blue wool or a known control fabric) to validate the test severity. For natural weathering, the standard stresses the importance of exposing the same set of specimens at multiple sites if the product is intended for different climatic regions. Regular recording of meteorological data is mandatory. For accelerated testing, the apparatus must be calibrated in accordance with ISO 4892-2 or ASTM G155, and the filtered xenon-arc spectrum must meet the spectral distribution limits defined in the standard.
Tip: When correlating accelerated and natural weathering results, always expose a set of control specimens with known field performance. The standard provides guidance on interpreting correlation factors but does not mandate a specific conversion method.
Compliance and Reporting
The test report must include the following: identification of the material, exposure method used (natural or accelerated), exposure duration / radiant exposure, any deviations from the standard procedure, and the results of property evaluations carried out before and after exposure. Changes in breaking strength (expressed as percentage retention), colour difference (ΔE* measured per CIELAB), and visual rating (e.g., no cracking, chalking, or delamination) must be reported. The standard also requires a statement of that the test was conducted in accordance with CAN CGSB 4.2 No. 39-2004 (2013), and the accreditation status of the testing laboratory if applicable.
Important: Specimens that show significant deterioration (e.g., strength loss > 50 %) may be considered to have failed the exposure test. However, the standard does not establish pass/fail criteria; these are normally defined by the relevant product specification or end-user requirement.
Good Practice: For quality control, it is recommended to include at least one set of intermediate exposure intervals (e.g., 100 h, 200 h, 400 h) to observe the rate of property change rather than only testing the final exposure point.
Warning: Natural weathering tests are highly dependent on geographic location and season. Results from a single site may not be representative of all end-use environments. Accelerated testing cannot fully replicate natural weathering and should only be used for comparative or screening purposes.
Frequently Asked Questions
Q: What is the main difference between CAN CGSB 4.2 No. 39-2004 (2013) and ASTM D5035 or ISO 105-B02?
A: While many principles are similar, the CGSB method includes specific exposure rack designs for Canadian climates, detailed requirements for natural weathering sites in Canada, and a mandatory reference material (CGSB standard control fabric). The accelerated method references Canadian filter and calibration requirements tailored to the Northern Hemisphere sunlight conditions.
A: While many principles are similar, the CGSB method includes specific exposure rack designs for Canadian climates, detailed requirements for natural weathering sites in Canada, and a mandatory reference material (CGSB standard control fabric). The accelerated method references Canadian filter and calibration requirements tailored to the Northern Hemisphere sunlight conditions.
Q: Can this standard be used for testing upholstery fabrics intended for interior use?
A: Yes, but only if the fabric is expected to experience direct sunlight through windows. For interior-only applications with no UV exposure, other CGSB 4.2 test methods (e.g., No. 38 for colourfastness to light) may be more appropriate. The standard advises that weathering tests are most relevant for outdoor or outdoor-adjacent textiles.
A: Yes, but only if the fabric is expected to experience direct sunlight through windows. For interior-only applications with no UV exposure, other CGSB 4.2 test methods (e.g., No. 38 for colourfastness to light) may be more appropriate. The standard advises that weathering tests are most relevant for outdoor or outdoor-adjacent textiles.
Q: Is the 2013 reaffirmation identical to the 2004 edition?
A: The reaffirmation reconfirmed the technical content without changes. Only editorial clarifications and updated references to related standards (e.g., ISO 4892-2) were incorporated. Users must obtain the 2013 version to ensure references are current, but test procedures remain unchanged from 2004.
A: The reaffirmation reconfirmed the technical content without changes. Only editorial clarifications and updated references to related standards (e.g., ISO 4892-2) were incorporated. Users must obtain the 2013 version to ensure references are current, but test procedures remain unchanged from 2004.
Last updated: 2026. This article provides general technical information; always refer to the official CAN CGSB 4.2 No. 39-2004 (2013) document for complete requirements.