CAN/CGSB-4.2 No./N° 18.1-M90

1.1 This method evaluates the colourfastness to light of textiles in all forms by exposing the material to the radiation from an enclosed carbon-arc. 1.2 The method may also be used to evaluate dye stuffs that have been applied to textiles under specified conditions and depth of shade. 1.3 Colorfastness to light is dependent upon factors such as the spectral distribution and intensity of the incident radiation, the moisture content and temperature at the surface of the material, the composition of the air surrounding it, whether the exposure to light is continuous or intermittent, and the method of mounting the specimen. For these reasons, the relative rates of fading may not be the same if materials are subjected to different conditions of exposure. 1.4 It should be noted that the committee considers the xenon-arc method (CAN/CGSB-4.2 No. 18.3-M) as the superior method. The spectral distribution of the xenon-arc light more closely duplicates daylight.