Combined Perspiration and Light Fastness Testing
topic
Combined perspiration and light fastness (ISO 105-B07, Perspiration Light Fastness, PLF) tests the synergistic degradation of dyed textiles under simultaneous artificial perspiration and light exposure — simulating the real-use conditions of summer sportswear, swimwear, and underwear worn during outdoor activity in direct sunlight with perspiration soaking the fabric. ISO 105-B07 procedure: specimen impregnated with ISO 105-E04 acid perspiration solution (pH 5.5) to 100% WPU, sandwiched between glass plates in xenon arc exposure frame, irradiated in xenon arc chamber (Q-Sun, Atlas Ci4000) at 0.35 W/m²/nm at 340 nm, 45°C blackboard temperature, 60% RH — test durations 1, 2, 4, 8, 20 AFU. Assessment: grey scale colour change versus unexposed dry specimen. Synergistic PLF degradation: reactive turquoise (Cu-phthalocyanine reactive dye on cotton) — xenon arc light fastness grade 5 (excellent), perspiration fastness grade 4 — combined PLF grade 3 at 4 AFU (synergistic 1–2 grade degradation from Cu chelation accelerated by UV photocatalysis in wet conditions). Reactive blue 163 (standard mid-blue) PLF grade 3–4 — typical mid-performance; vat dyes (Indanthrene Blue CLF) PLF grade 5–6 — best combined resistance. AATCC TM125 (perspiration lightfastness, similar wet xenon arc approach, used by US brands for swimwear specification): condition specification 4 AFU exposure, grade ≥ 4 minimum for premium swimwear. Swimwear PLF specification: chlorinated water plus UV exposure (AATCC TM162 chlorine fastness + ISO 105-B07 combined): grade ≥ 3-4 for mainstream swimwear, grade ≥ 4-5 for premium competitive swimwear with 200+ hours UV exposure claimed service life.
Role
Combined perspiration-light fastness testing captures synergistic colour degradation mechanisms that individual perspiration and light fastness tests completely miss — providing the critical quality data for summer sportswear and swimwear where simultaneous UV and perspiration exposure is the primary in-use condition, making PLF testing the most technically realistic and predictively valid fastness test for the $35 billion global activewear and swimwear market.