Colour Fastness to Light and Weathering
topic
Colour fastness to light testing exposes dyed fabric specimens alongside ISO blue wool reference standards under a xenon arc or daylight source until the reference standard shows grade 3 fading, then grading the specimen against the blue wool scale from 1 (severe fading) to 8 (no fading); combined weathering fastness tests add moisture exposure to simulate outdoor conditions.
Role
Provides the light fastness rating that determines suitability of dye-substrate combinations for outdoor, automotive, and home furnishing applications where prolonged UV exposure must not cause unacceptable colour fading or metameric shift within the specified product service life.