Colour Fastness to Perspiration Testing

Colour fastness to perspiration evaluates the resistance of dyed textiles to colour change and staining under simulated acid and alkaline perspiration conditions — critical for all skin-contact apparel because human perspiration (pH 4.5–7.5 depending on body location and individual) contacts dyed fabric during wear, particularly in high-perspiration areas (underarm, collar, back, cuffs). ISO 105-E04 (perspiration fastness, SDL Atlas Perspirometer, James Heal Perspirometer): specimens impregnated with standardised artificial perspiration solutions (acid: 0.5 g/L L-histidine monohydrochloride monohydrate, 5 g/L NaCl, 2.2 g/L NaH₂PO₄, pH 5.5 ±0.2; alkaline: same without histidine, with 5 g/L Na₂HPO₄, pH 8.0 ±0.2) — impregnated specimen placed between multifibre DW adjacent fabric, loaded in perspirometer frame under 4.5 kPa (500 g weight), placed in oven at 37 ±2°C for 4 hours, dried at <60°C, assessed by grey scale. AATCC TM15 (American equivalent, similar composition but NaCl 10 g/L, histidine 0.25 g/L, lactic acid replaces phosphate buffer, pH 4.3 ± 0.2) — results approximately equivalent to ISO 105-E04 acid condition ±0.5 grade. Perspiration fastness specification: skin-contact apparel minimum acid and alkaline grade 3-4 colour change, grade 3 staining (ISO 105-E04); OEKO-TEX Standard 100 direct skin contact: colour change ≥ 3-4, staining ≥ 3 on all adjacent fibre strips. Dye class sensitivity to perspiration: reactive dyes (excellent alkali stability — reactive bond stable to pH 8.0, acid condition may partially hydrolyse at pH 5.5, grade 3-4); acid dyes on wool (excellent acid stability, poor alkaline — grade 2-3 alkaline for some acid dye classes); direct dyes (poor overall, grade 2-3); disperse dyes on polyester (grade 4-5, virtually unaffected by perspiration pH).