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CAN CGSB 4.2 No. 60-M89 (2013): A Comprehensive Guide to Colourfastness to Light Testing for Textiles
Understanding the Canadian Standard for Evaluating Colourfastness of Textiles to Light Exposure
Scope and Applicability
CAN CGSB 4.2 No. 60-M89 (2013) is a mature Canadian national standard that specifies test methods for determining the colourfastness of textiles to the action of light. First published in 1989 and reaffirmed in 2013, this standard remains a cornerstone for evaluating lightfastness in the Canadian textile industry. It applies to all types of textile materials, including woven, knitted, and nonwoven fabrics, as well as yarns and threads, regardless of fibre composition or colourant type. The standard is widely referenced by manufacturers, testing laboratories, retailers, and regulatory bodies to ensure that coloured textiles maintain their appearance when exposed to indoor or outdoor lighting conditions.
The principal methods described in the standard involve exposing specimens to artificial light sources (xenon arc or carbon arc) under controlled conditions of irradiance, temperature, and humidity. The colour change of the specimens is then assessed against the standard blue wool references (L2 to L9) or using instrumental colour measurement. This standard is harmonized with international practices such as ISO 105-B02 and AATCC TM 16, but it adapts the methodology to Canadian climatic considerations and industry requirements.
CAN CGSB 4.2 No. 60-M89 (2013) is part of the larger CGSB 4.2 series of textile test methods, covering mechanical, chemical, and colourfastness evaluations. When citing this standard, always include the reaffirmation year (2013) to indicate the current valid version.
Technical Requirements
Test Principles and Light Sources
The fundamental principle is to expose textile specimens together with a set of blue wool reference standards to a controlled light source. The light source must simulate natural daylight, and the standard specifies the use of either a xenon arc lamp (with appropriate filters) or a carbon arc lamp. The xenon arc is preferred for its closer spectral match to sunlight, while the carbon arc is still permitted for legacy compliance. The standard defines two exposure methods:
- Method 1 – Continuous light exposure without humidity control: Suitable for general colourfastness assessment.
- Method 2 – Alternating light and dark cycles including controlled humidity: Used to simulate more realistic conditions, particularly for textiles that may undergo wet conditions during use.
Equipment Specifications
The apparatus must meet rigorous criteria. For the xenon arc method, the standard requires:
- Black panel thermometer (BPT) capable of maintaining 63 ± 3 °C (or adjustable per agreed conditions).
- Chamber temperature controlled to 43 ± 2 °C.
- Relative humidity (RH) control: low (20–30% RH), moderate (40–50% RH), or high (60–70% RH), depending on the application.
- Irradiance control at 1.10 ± 0.03 W/(m²·nm) at 420 nm (or equivalent).
The table below summarizes the main exposure conditions for the xenon arc method:
| Parameter | Value | Tolerance |
|---|---|---|
| Black panel temperature (BPT) | 63 °C | ± 3 °C |
| Chamber air temperature (dry bulb) | 43 °C | ± 2 °C |
| Relative humidity (moderate) | 50 % | ± 5 % |
| Irradiance (at 420 nm) | 1.10 W/(m²·nm) | ± 0.03 W/(m²·nm) |
| Light/dark cycle (Method 2) | 102 min light / 18 min dark | — |
Blue Wool References and Grading
The standard uses eight blue wool references (L2 to L9) that fade in a known stepwise manner. L2 fades most rapidly, while L9 is very resistant. After exposure, the colour change of the test specimen is rated by comparison with the fading of the blue wool references. The rating scale is from 1 (very poor lightfastness) to 8 (outstanding lightfastness). Alternatively, instrumental colour measurement (e.g., CIELAB ΔE) can be used for objective grading, but the visual rating remains the primary method.
Care must be taken to ensure that the blue wool references are properly calibrated and stored in the dark when not in use. Any degradation before testing will invalidate the entire exposure series.
Implementation Highlights
Sample Preparation
Specimens should be representative of the finished textile, including any finishing treatments. For fabrics, cut specimens of at least 100 mm × 75 mm. For yarns, wind a flat layer on a suitable backing card. When comparing different materials, ensure identical backing materials are used to avoid variability in reflectance or thermal properties. The standard also provides guidance on combining multicolour specimens and using inherent moisture content control.
Exposure Procedure
The test specimens and the blue wool references are mounted on a specimen holder in the exposure chamber. For Method 1, the light is continuous until the desired exposure (up to the fading of specified blue wool references) is achieved. For Method 2, a cycle of 102 minutes of light and 18 minutes of dark is used with water spray or high humidity during the dark cycle, simulating light and dew conditions. The exposure is terminated when the fading of a predetermined blue wool reference (e.g., L4) reaches a grey scale rating of 4 (contrast with unexposed portion).
Assessment
After exposure, the specimens are conditioned in the dark at standard atmosphere (21 ± 1 °C, 65 ± 2% RH) for at least 24 hours before evaluation. Colour change is assessed under standardized lighting (e.g., D65 illuminant) using the grey scale for colour change (ISO 105-A02/A03) or by direct comparison with the exposed blue wool references. The final grade is assigned as the number of the blue wool reference (L2 to L9) that shows a similar degree of fading. Interpolated half‑grades (e.g., 5, 6‑7) may be reported.
To enhance reproducibility, laboratories should include a known “control” fabric with established lightfastness in each exposure run. This practice helps identify abnormal chamber behaviour or lamp aging.
Compliance Notes and Best Practices
Sampling and Homogeneity
Because light sensitivity can vary across a textile lot, the standard recommends taking specimens from at least three random locations. If any specimen deviates by more than one grade from the average, the entire lot should be retested. This ensures that the reported lightfastness rating is representative and not influenced by local variations in dye uptake or finishing.
Lab Accreditation and Quality Control
Testing laboratories should hold accreditation (e.g., ISO/IEC 17025) with a scope that includes this standard. Regular interlaboratory comparisons are essential for maintaining consistency. All instruments used (xenon arc lamps, black panel thermometers, humidity sensors) must be calibrated at intervals specified by the manufacturer, and calibration records must be traceable to national standards.
Reporting
The test report must include the following minimum information:
- Reference to CAN CGSB 4.2 No. 60-M89 (2013)
- Method used (Method 1 or 2)
- Light source type (xenon arc or carbon arc)
- Exposure conditions (BPT, temperature, RH, irradiance, cycle)
- Grade assigned (visual or instrumental)
- Any deviations from the standard procedure
Safety precaution: Xenon arc lamps emit intense ultraviolet (UV) radiation and generate high heat. Operators must wear UV-protective eyewear and shielding. Carbon arc lamps also produce hazardous fumes and require adequate ventilation and personal protective equipment.
Frequently Asked Questions
Q: How does CAN CGSB 4.2 No. 60-M89 compare to ISO 105-B02?
A: The two standards are very similar in test principle, equipment requirements, and blue wool grading scale. CAN CGSB 4.2 No. 60-M89 includes additional guidance specific to Canadian climatic conditions and references Canadian blue wool supplies. It also retains the carbon arc as an alternative light source, which is less common in ISO. For global trade, many laboratories validate equivalency between the two methods.
A: The two standards are very similar in test principle, equipment requirements, and blue wool grading scale. CAN CGSB 4.2 No. 60-M89 includes additional guidance specific to Canadian climatic conditions and references Canadian blue wool supplies. It also retains the carbon arc as an alternative light source, which is less common in ISO. For global trade, many laboratories validate equivalency between the two methods.
Q: Can this standard be applied to automotive interior textiles?
A: While the standard can technically be used for automotive fabrics, severe automotive interior lightfastness requirements often demand longer exposures and tighter irradiance control not explicitly covered in this standard. For automotive applications, refer to SAE J2412 (xenon arc for interior trim) or SAE J2527. The CGSB standard is more suited to apparel, home textiles, and general industrial fabrics.
A: While the standard can technically be used for automotive fabrics, severe automotive interior lightfastness requirements often demand longer exposures and tighter irradiance control not explicitly covered in this standard. For automotive applications, refer to SAE J2412 (xenon arc for interior trim) or SAE J2527. The CGSB standard is more suited to apparel, home textiles, and general industrial fabrics.
Q: What is the significance of the “M89 (2013)” designation?
A: “M89” indicates that the standard was originally issued in 1989. The “(2013)” parentheses show that it was reaffirmed in 2013 without technical changes, confirming that it is still the current version. Users must always verify the latest reaffirmation date, as CGSB may re‑approve or revise future editions.
A: “M89” indicates that the standard was originally issued in 1989. The “(2013)” parentheses show that it was reaffirmed in 2013 without technical changes, confirming that it is still the current version. Users must always verify the latest reaffirmation date, as CGSB may re‑approve or revise future editions.
Q: Is it mandatory to use blue wool references for grading, or can instrumental measurement replace them?
A: The standard requires visual comparison with blue wool references as the primary grading method. Instrumental measurement may be used as an alternative only if it is validated against the visual method and agreed between parties. In case of dispute, the visual rating using blue wool references takes precedence.
A: The standard requires visual comparison with blue wool references as the primary grading method. Instrumental measurement may be used as an alternative only if it is validated against the visual method and agreed between parties. In case of dispute, the visual rating using blue wool references takes precedence.