Acid and Alkaline Perspiration Fastness ISO 105-E04
topic
ISO 105-E04 perspiration fastness procedure requires preparation of two standardised artificial perspiration solutions, separate impregnation of two specimens (one acid, one alkaline), assembly into perspirometer frames, incubation, and grey scale assessment. Acid solution preparation: dissolve 0.5 g L-histidine monohydrochloride monohydrate + 5.0 g NaCl + 2.2 g NaH₂PO₄·2H₂O in 1,000 mL distilled water, adjust pH to 5.5 ±0.2 with 0.1 N NaOH. Alkaline solution: 0.5 g histidine + 5.0 g NaCl + 2.5 g Na₂HPO₄·12H₂O per 1,000 mL, pH 8.0 ±0.2 adjusted with 0.1 N NaOH. Specimen impregnation: immerse specimen + attached multifibre DW (100 mm × 40 mm combined) in respective solution for 30 minutes at room temperature, squeeze to 100% WPU (weight pickup), place specimen face-to-face with adjacent fabric in perspirometer frame. Perspirometer frame (SDL Atlas, James Heal): sandwich of glass or acrylic plates (11.5 × 6 cm) with specimen between adjacent fabrics, loaded to 4.5 kPa by 5 kg weight distributed over 50 cm² footprint → 4 hours at 37°C oven → remove, unfold, dry separately at <60°C (do not iron). Assessment under D65 illuminant (1,000 lux, 45/0° geometry viewing angle): colour change of specimen (grey scale A02), staining of each adjacent fibre strip (grey scale A03). Histidine function: L-histidine (an amino acid present in human axillary perspiration at 0.1–0.5 g/L) acts as a weak metal complexing agent — histidine sequesters iron, copper, and chromium ions from mordant and metal-complex dyes, accelerating colour change that occurs on skin contact in real perspiration. Metal-complex dyes (acid dyes with Cu, Cr, Co chelation): particularly sensitive to histidine in ISO 105-E04 acid solution — chrome dye on wool may give grade 2–3 perspiration due to histidine chelation, despite excellent washing fastness grade 4–5.
Role
Acid and alkaline perspiration testing with histidine is the standardised simulation of the most chemically complex skin-contact fastness scenario — histidine-mediated metal chelation from mordant dyes represents a real mechanism of perspiration-induced colour change that pH alone cannot capture, making ISO 105-E04 the technically superior method for predicting actual in-use perspiration fastness compared to simpler acid/alkali soaking tests.