Pigment Print Colour Fastness Testing

Pigment print fastness testing assesses the retention of pigment-binder film on fabric surface under mechanical and chemical stress — the dominant performance limitation of pigment printing compared to dye-based methods. Pigment print washing fastness (ISO 105-C06, condition A1S, 40°C, 30 min, 10 balls): printed area colour change grade 3–4 (good for standard acrylic binder) — binder crosslink density determines wash fastness: inadequately crosslinked binder (undercured or incorrect hardener ratio) gives grade 2–3 (binder swells in water, allowing pigment detachment). Rubbing fastness of pigment prints (ISO 105-X12, dry grade 4–5, wet grade 3–4): wet rubbing most challenging — binder film softens slightly in water, increasing pigment transfer to rubbing cloth; heavy pigment loading (>50 g/m²) reduces wet crocking by 0.5–1.0 grade due to surface pigment not fully penetrated by binder. Elongation of pigment print film (relevant for stretch substrate printing): standard acrylic binder elongation 20–30% (insufficient for stretch jerseys extending 50–80% — binder cracks on stretching, causing print cracking and wash-off degradation after 5–10 wash cycles); polyurethane (PU) binder elongation 150–300% (suitable for stretch printing — maintains grade 3–4 washing after 20 wash cycles at 40% substrate extension). Pigment print light fastness (ISO 105-B02, xenon arc): organic pigment (azo pigment, phthalocyanine) grade 5–6; inorganic pigment (titanium dioxide white, iron oxide) grade 7–8 — pigment selection for outdoor applications must prioritise light fastness over colour range. Binder film cracking accelerated test (AATCC TM130 adapted: fabric flexed 1,000 cycles at −10°C cold flex test — simulates winter garment handling): PU binder at −10°C retains film integrity; standard acrylic binder cracks below −5°C (glass transition temperature issue — Tg of acrylic binder 5–15°C, below ambient use temperature causing brittleness).