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CAN CGSB 4.2 No. 36-M89 (2013): Standard Test Method for Colourfastness of Textiles to Light
A comprehensive guide to the CGSB method for assessing lightfastness in textile materials
Introduction
CAN CGSB 4.2 No. 36-M89 (2013) is a prominent Canadian standard developed by the Canadian General Standards Board (CGSB) that specifies a method for determining the resistance of textile colour to the action of light. This standard is part of the CGSB 4.2 series of textile test methods and is identical in technical content to the well‑known ISO 105‑B02 method for colourfastness to artificial light. Originally published in 1989 as CAN/CGSB 4.2 No. 36‑M89, it was reaffirmed in 2013, confirming its continued relevance for textile quality assurance in Canada and beyond.
The test method employs a xenon arc lamp to simulate natural daylight, under controlled temperature and humidity conditions, and uses a set of blue wool reference materials for evaluation. This article provides a detailed examination of the standard’s scope, technical requirements, implementation highlights, and compliance notes.
Scope of the Standard
CAN CGSB 4.2 No. 36-M89 (2013) applies to all textile products – including woven, knitted, nonwoven, and coated fabrics – regardless of fibre type or construction. The standard defines a method for:
- Determining the resistance of the colour of textiles to the action of an artificial light source.
- Assessing the colour change of specimens after exposure to a defined optical energy.
- Classifying lightfastness using the blue wool scale (grades 1 to 8).
The method is intended for use in quality control, product development, and specification compliance. It does not provide pass/fail limits – those are established by the relevant product standard or purchasing agreement. The standard is applicable to both dyed and printed textiles and to textile items such as yarns, threads, and fibres in fabric form.
Tip: For textiles intended for extreme exposure (e.g., automotive interiors, outdoor furniture), consider combining this method with a weathering test that includes water spray, as described in CAN CGSB 4.2 No. 38.
Technical Requirements and Test Procedure
Apparatus and Materials
The standard requires the use of a xenon arc fading apparatus equipped with appropriate filters to simulate the spectral distribution of sunlight (especially the ultraviolet portion). Key components include:
- Xenon arc lamp with borosilicate inner and outer filters (or equivalent).
- Sample holders capable of exposing both the test specimen and the blue wool references simultaneously.
- Temperature- and humidity-control systems (black standard thermometer, psychrometer or other humidity sensor).
- Blue wool references (grades 1 to 8) conforming to ISO 105‑B01.
- Grey scale for assessing colour change (ISO 105‑A02).
Specimen Preparation
Test specimens are prepared in duplicate, typically 40 mm × 50 mm, and mounted in the sample holder so that a portion is covered to provide an unexposed reference area. The standard advises preconditioning the specimens in the standard atmosphere for textile testing (20 ± 2 °C, 65 ± 4 % RH) prior to mounting.
Exposure Conditions
The exposure chamber is operated under the following standard conditions:
| Parameter | Requirement |
|---|---|
| Irradiance at specimen plane | 42 W/m² (300–400 nm) |
| Black standard temperature | 47 ± 3 °C |
| Relative humidity | 40 ± 5 % (for normal conditions) |
| Chamber air temperature | 30 ± 5 °C |
| Light/dark cycling | Continuous light – no dark cycles |
Other conditions may be specified for particular end‑use applications (e.g., higher humidity for tropical exposure simulation). The standard also provides for exposure using a “light only” cycle (without water spray).
Blue Wool Reference Scale
Lightfastness is classified by exposing the specimen simultaneously with eight blue wool references. The reference grades range from 1 (very low fastness) to 8 (outstanding fastness). The exposure is continued until a specific contrast is reached on a particular reference – typically until the colour change on the specimen is judged equal to the colour change on the reference number that corresponds to the durability requirement.
Important: The blue wool references are sensitive to humidity and temperature. They must be stored in a cool, dark place and replaced after a maximum of two years or after visible fading, whichever occurs first. Always validate each new batch against a known reference.
Assessment of Colour Change
After exposure, the specimen is removed and the colour change is assessed visually under standard daylight conditions (D65 illuminant). The grey scale for assessing change in colour is used to rate the degree of fading. The final rating is the blue wool grade number that exhibits a colour change corresponding to that of the specimen (or the number where the specimen shows a change equal to the grey scale contrast of grade 3–4 or whichever endpoint is desired).
Good practice: Conduct the assessment in a viewing cabinet with a 45/0 geometry and ensure that the observer is not colour‑blind. Regular inter‑laboratory comparisons (round‑robins) help maintain consistency.
Implementation Highlights
Laboratory Accreditation and Competence
Laboratories intending to perform CAN CGSB 4.2 No. 36‑M89 (2013) for certification or regulatory purposes should be accredited to ISO/IEC 17025. The standard requires careful control of exposure parameters, periodic calibration of the irradiance sensor, black standard thermometer, and humidity sensor. Logging of all parameters during the test is essential for traceability.
Relation to International Standards
CAN CGSB 4.2 No. 36‑M89 (2013) is technically equivalent to ISO 105‑B02 and AATCC TM 16.3. Many manufacturers and specifiers accept the CGSB method as an alternative to these standards, provided that the test report clearly identifies the method used. This harmonisation simplifies global textile trade, as test results generated under any of the three standards are considered comparable.
Common Deviations and Modifications
Users should be aware that certain industries (e.g., automotive, aeronautics) may have additional requirements, such as extended exposure times or higher operating temperatures. In such cases, the standard can be used as a baseline, and the modified conditions must be documented. The standard’s “Notes” section offers guidance on adjusting irradiance levels to accelerate testing for materials that exhibit high lightfastness.
Compliance and Quality Assurance Notes
Compliance with CAN CGSB 4.2 No. 36‑M89 (2013) is often a contractual or regulatory requirement for textile products sold in Canada. The standard is referenced in several Canadian government procurement specifications, as well as in private sector brand standards. A test report should include:
- Full standard designation (including the reaffirmation year).
- Sample description and preparation details.
- Exposure conditions used (if deviating from the standard).
- Blue wool reference batch number.
- Lightfastness grade (1–8) and the rating scale endpoint used (e.g., grey scale contrast 3–4).
- Date of test and signature of responsible technician.
Critical: If the reported lightfastness grade is lower than the minimum level required by the applicable product specification, the material must be returned for re‑engineering or rejected. A common minimum requirement for apparel textiles is grade 4 (good fastness), but for swimwear, outdoor gear, or drapery, a grade 6 or higher may be demanded.
Frequently Asked Questions
Q: What is the difference between CAN CGSB 4.2 No. 36-M89 (2013) and ISO 105-B02?
A: Both standards are technically identical; they describe the same test method, apparatus, and evaluation procedure. The primary difference is the issuing body and the national designation. In practice, a test performed according to CAN CGSB 4.2 No. 36‑M89 (2013) can be submitted wherever ISO 105‑B02 is required, as long as the method is explicitly referenced in the test report.
A: Both standards are technically identical; they describe the same test method, apparatus, and evaluation procedure. The primary difference is the issuing body and the national designation. In practice, a test performed according to CAN CGSB 4.2 No. 36‑M89 (2013) can be submitted wherever ISO 105‑B02 is required, as long as the method is explicitly referenced in the test report.
Q: Can this standard be used for non‑textile materials such as leather or plastic?
A: CAN CGSB 4.2 No. 36‑M89 (2013) is written specifically for textiles. For leather, the applicable CGSB method is CAN/CGSB 4.2 No. 38 (which includes water spray), and for plastics, one should refer to ASTM D2565 or ISO 4892. However, the principle of using a xenon arc and blue wool references is similar, so the general concepts apply.
A: CAN CGSB 4.2 No. 36‑M89 (2013) is written specifically for textiles. For leather, the applicable CGSB method is CAN/CGSB 4.2 No. 38 (which includes water spray), and for plastics, one should refer to ASTM D2565 or ISO 4892. However, the principle of using a xenon arc and blue wool references is similar, so the general concepts apply.
Q: How often should the xenon arc lamp be replaced?
A: The lamp life depends on operating hours and on the stability of the irradiance. The standard recommends replacing the lamp when the irradiance can no longer be maintained at 42 W/m² in the 300–400 nm band, or after approximately 1500 hours of use. Regular spectral checks are advised.
A: The lamp life depends on operating hours and on the stability of the irradiance. The standard recommends replacing the lamp when the irradiance can no longer be maintained at 42 W/m² in the 300–400 nm band, or after approximately 1500 hours of use. Regular spectral checks are advised.
Q: What does “M89” refer to in the standard number?
A: “M” stands for “Manufacturing and Processing Standard” (according to CGSB classification), and “89” identifies the original year of publication (1989). The reaffirmation year (2013) is shown in parentheses. Thus, the full number signifies that the standard was originally issued in 1989 and reaffirmed without technical changes in 2013.
A: “M” stands for “Manufacturing and Processing Standard” (according to CGSB classification), and “89” identifies the original year of publication (1989). The reaffirmation year (2013) is shown in parentheses. Thus, the full number signifies that the standard was originally issued in 1989 and reaffirmed without technical changes in 2013.
© 2026 – Canadian General Standards Board – This article is for informational purposes only. Always refer to the official published standard for complete requirements.