CAN CGSB 4.2 No. 20-M89 (2013) – Colorfastness to Light: Xenon Arc Lamp Test Method

Scope and Application

CAN CGSB 4.2 No. 20-M89 (2013) is a method of test issued by the Canadian General Standards Board (CGSB) for determining the colourfastness of textiles to light. The standard specifies a procedure using a xenon arc lamp as the light source, which closely simulates natural sunlight, particularly the ultraviolet and visible spectrum. It applies to all types of textiles—woven, knitted, and nonwoven—and to textile products such as yarns and felts. The method assesses the resistance of colour to fading or change under controlled exposure to light, heat, and moisture.

This standard is part of the CGSB 4.2 series of textile test methods and is technically equivalent to ISO 105-B02, though it retains specific Canadian requirements regarding conditioning and reporting. It is widely referenced in Canadian and North American textile procurement specifications, particularly for uniforms, protective clothing, and home furnishings.

Technical Requirements and Test Conditions

Test Apparatus and Environmental Control

The test requires a xenon arc lamp apparatus capable of maintaining specified irradiance, temperature, and humidity. The equipment must be equipped with appropriate filters (borosilicate or soda lime glass) to simulate sunlight after passage through window glass or direct sunlight. The black panel temperature is controlled at 63°C ± 3°C, and relative humidity is set according to the climatic region being simulated. Two standard humidity conditions are defined:

• Temperate: 40% ± 5% RH, 63°C black panel
• Tropical: 60% ± 5% RH, 63°C black panel

The irradiance level is maintained at 1.10 W/(m²·nm) at 420 nm. Spectroradiometric calibration is required at regular intervals to ensure consistent output.

Test Specimens and Reference Materials

Specimens are exposed alongside a set of blue wool references (grades 1 to 8) that indicate the lightfastness scale. The change in colour of the specimen and the reference standards is assessed using the grey scale for colour change (ISO 105-A02). The end point for exposure is determined when a specified contrast is reached on the reference standard.

Exposure and Grading

Exposure is conducted in a cycle that may include intermittent dark periods or water spray if required by a particular specification. At the conclusion of the test, the colour change of the specimen is rated against the blue wool scale. The result is expressed as a numerical lightfastness grade from 1 (very poor) to 8 (excellent).

Implementation in Textile Testing Laboratories

Preparation and Calibration

Laboratories implementing this standard must establish documented procedures for machine maintenance, calibration of irradiance sensors and temperature probes, and regular verification using certified reference materials. An initial performance check using blue wool grade 4 ensures the apparatus is operating correctly.

Reporting Results

The test report must include: standard reference (CAN CGSB 4.2 No. 20-M89 (2013)), specimen identification, lightfastness grade, exposure conditions (temperate or tropical), and any deviations from the standard. When grading for a specific end-use, a minimum grade may be contractually required (e.g., grade 4 for apparel, grade 6 for automotive interior fabrics).

Compliance and Certification Notes

Compliance with CAN CGSB 4.2 No. 20-M89 (2013) is often required by Canadian federal and provincial procurement policies. Textile products that meet the standard may be eligible for certification under CGSB’s voluntary conformity assessment program. Manufacturers should ensure their test reports are issued by laboratories accredited to ISO/IEC 17025 for this specific method.

Item 20 of the CGSB 4.2 series is periodically reaffirmed; the 2013 version is the most current. Users should always verify that they are applying the latest reaffirmation, as technical interpretations may evolve.

Frequently Asked Questions