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CAN CGSB 4.2 No. 37-2002 (2013): Textile Colourfastness to Light Test Using Xenon Arc Lamp
A comprehensive overview of the Canadian standard for assessing textile colourfastness to artificial light, reaffirmed in 2013.
Scope and Application
CAN CGSB 4.2 No. 37-2002 (2013) — part of the CGSB 4.2 series of textile test methods — specifies a procedure for determining the resistance of the colour of textiles to the action of artificial light. The test method uses a xenon arc lamp equipped with suitable filters to simulate natural daylight, and it is applicable to all types of textile materials, whether dyed, printed, or otherwise coloured.
This standard is an adoption of ISO 105-B02 with modifications tailored to Canadian environmental conditions and end-use requirements. It is intended for use by textile manufacturers, testing laboratories, and quality assurance organizations to evaluate the colourfastness of products that are exposed to light during storage, display, or use. The method assesses the degree of change in colour after exposure to a controlled light source under specified conditions of temperature and humidity.
The 2013 reaffirmation confirms that the technical content remains current and no substantive changes were introduced; therefore, the 2002 edition continues to be the valid reference for conformity assessment in Canada.
Technical Requirements
Test Apparatus and Materials
The test requires a xenon arc light source that reproduces the spectral power distribution of natural daylight, especially in the ultraviolet (UV) region. The following key components are specified:
- Xenon arc lamp with air- or water-cooling and borosilicate or quartz filters to match daylight (D65 or equivalent).
- Black-standard thermometer (BST) for measuring black-standard temperature (typically 45°C ± 3°C).
- Humidity control using a humidification system to achieve the required relative humidity, verified by the red dosimeter scale or by controlled humidity sensors.
- Reference materials: Eight standard blue wool references (Grades 1 to 8) from ISO 105-B02, each having a known lightfastness rating.
- Light exposure device capable of maintaining uniform irradiance and temperature across the test specimens.
Test Specimen Preparation
Two sets of specimens are prepared for each textile sample: one for exposure and a duplicate that is kept in the dark for comparison. The specimen size and mounting orientation are defined to ensure reproducible irradiance distribution. For loose fibres or yarns, special mounting procedures are described in the standard.
Exposure and Evaluation
The exposure is carried out in cycles, each cycle consisting of a light period (with or without intermittent dark phases). The total exposure duration is defined by the user or by a specification, and the standard provides a method to determine the exposure time using the blue wool references. The two main methods are:
| Method | Description | Evaluation Criteria |
|---|---|---|
| Method 1 (Standard exposure) | Expose the specimen and a set of blue wool references together until the contrast of a specified blue wool letter (e.g., L2 or L4) is reached. | Compare colour change against the grey scale (AATCC or ISO) and report the lightfastness grade (e.g., 4, 5, etc.). |
| Method 2 (Step exposure) | Expose the specimen along a series of blue wool references under controlled conditions, then compare the change in colour with the change in each reference. | The lightfastness rating is the number of the highest blue wool reference that shows a similar change. |
All evaluations must be performed under a standard light booth (D65 illuminant) or with a colorimeter if objective measurement is required. The standard includes acceptance criteria for different end-use categories (interior, outdoor, automotive, etc.).
Tabulated Test Conditions
| Parameter | Specification |
|---|---|
| Light source | Xenon arc lamp with daylight filters (borosilicate or quartz) |
| Irradiance | 1.10 W/m² at 420 nm (typical) |
| Black-standard temperature (BST) | 45°C ± 3°C |
| Relative humidity (conditional) | 30%–70% depending on climate class (temperate, desert, tropical) |
| Exposure cycle | Continuous or alternating light/dark (e.g., 1%–2% dark time) to prevent overheating |
| Reference materials | Blue wool standards No. 1 to 8 (ISO 105-B02) |
Tip: Always precondition the specimens at a standard atmosphere (20°C ± 2°C, 65% ± 4% RH) for at least 4 hours before mounting. This reduces variability caused by moisture or temperature gradients. Proper mounting is critical to avoid shadowing or uneven exposure.
Warning: The xenon arc lamp emits intense UV radiation that can cause severe skin and eye injuries. Never operate the equipment without interlocking shields or UV‑filtering windows. Regular calibration of the temperature and humidity sensors is mandatory to maintain test reproducibility.
Implementation and Best Practices
Successful implementation of CAN CGSB 4.2 No. 37-2002 (2013) requires careful attention to the uniformity of the light field, the accuracy of the temperature and humidity control, and the correct use of blue wool references. Laboratories should:
- Calibrate the irradiance and temperature sensors at least every six months or after every 500 hours of lamp operation.
- Replace filters according to the manufacturer’s recommendations to maintain spectral distribution.
- Use fresh blue wool references for each test series and store them in opaque, moisture‑proof containers.
- Conduct colour change evaluations immediately after equilibration of the exposed specimen to a standard atmosphere (usually 1‒2 hours).
The standard allows the use of either visual assessment (using grey scales or blue wool ratings) or instrumental measurement (spectrophotometric colour difference). For arbitration, instrumental evaluation is strongly recommended.
Proven reliability: Laboratories that adopt the rigorous control of temperature and humidity as per this standard have reported a significant reduction in inter‑laboratory variability, making the test results more comparable across different facilities. The harmony with ISO 105‑B02 also facilitates international trade and product acceptance.
Common pitfall: One frequent error is using an incorrect humidity setting for the desired climatic classification (temperate vs. desert). The standard provides a humidity calibration method using a control test specimen of red azoic dye (the “red dosimeter”); skipping this step can lead to incorrectly optimistic or pessimistic lightfastness grades.
Compliance and Conformity
Compliance with CAN CGSB 4.2 No. 37-2002 (2013) is often required by Canadian retailers, procurement agencies, and consumer protection regulations. When a product is claimed to be “tested to CAN CGSB 4.2 No. 37”, the test report must show:
- The exact method used (Method 1 or 2).
- The exposure conditions (temperature, humidity, irradiance).
- The lightfastness grade(s) obtained.
- The date of testing and the laboratory’s accreditation (if any).
It is important to note that the standard does not set pass/fail criteria; those are defined by product specifications or contractual agreements. Common industry acceptance levels are grade 4 for interior trims, grade 5 for outdoor textiles, and grade 6 or higher for automotive fabrics.
The 2013 reaffirmation by the Canadian General Standards Board ensures that this test method remains fully aligned with the latest Canadian safety and quality requirements. Users are encouraged to check the CGSB website regularly for any amendments or interpretations.
Frequently Asked Questions
Q: How does CAN CGSB 4.2 No. 37-2002 (2013) differ from ISO 105-B02?
A: The two documents are technically identical in their test procedures. However, the Canadian standard includes additional notes on climate classification (e.g., a more detailed description of the humidity control methods for Canadian winters) and specifies that the test report must reference the Canadian standard number when used for domestic conformity. For international trade, ISO 105‑B02 is commonly recognised, but many companies include both references to satisfy local and global requirements.
A: The two documents are technically identical in their test procedures. However, the Canadian standard includes additional notes on climate classification (e.g., a more detailed description of the humidity control methods for Canadian winters) and specifies that the test report must reference the Canadian standard number when used for domestic conformity. For international trade, ISO 105‑B02 is commonly recognised, but many companies include both references to satisfy local and global requirements.
Q: Can I use this standard for interior textiles like curtains or bedding?
A: Yes, this standard is applicable to all textiles exposed to light during normal use, including home furnishings, apparel, and technical textiles. The end‑use category (indoor, outdoor, automotive) will determine the required lightfastness grade, but the test method itself remains the same.
A: Yes, this standard is applicable to all textiles exposed to light during normal use, including home furnishings, apparel, and technical textiles. The end‑use category (indoor, outdoor, automotive) will determine the required lightfastness grade, but the test method itself remains the same.
Q: What is the recommended frequency for verifying the test equipment?
A: The standard advises that the irradiance and black‑standard temperature sensors be calibrated at least every six months of operation or after 500 hours of lamp use, whichever comes first. The humidity control should be checked with a calibrated hygrometer before each exposure set, preferably using the red dosimeter procedure mentioned in the standard. Records of calibration must be kept for audit purposes.
A: The standard advises that the irradiance and black‑standard temperature sensors be calibrated at least every six months of operation or after 500 hours of lamp use, whichever comes first. The humidity control should be checked with a calibrated hygrometer before each exposure set, preferably using the red dosimeter procedure mentioned in the standard. Records of calibration must be kept for audit purposes.
Q: Is it possible to test very dark or thick materials with this method?
A: Yes, but special care must be taken with temperature control: dark colours absorb more radiant energy and can overheat the specimen surface. In such cases, the standard allows reducing the exposure irradiance or using a stepped exposure method to avoid melting or scorching. Always mount poorly conductive materials on a heat‑sink backing plate and monitor the BST closely.
A: Yes, but special care must be taken with temperature control: dark colours absorb more radiant energy and can overheat the specimen surface. In such cases, the standard allows reducing the exposure irradiance or using a stepped exposure method to avoid melting or scorching. Always mount poorly conductive materials on a heat‑sink backing plate and monitor the BST closely.
© 2026 Canadian General Standards Board – This article is for informational purposes and does not replace the official standard document.