Overview
ISO 25089:2025 - Leather - Tests for colour fastness - Colour fastness to sea water specifies a laboratory method to determine how leather of all kinds resists colour change and staining when exposed to sea water (saltwater). Developed jointly with IULTCS (IUF 422), the standard covers specimen preparation, test apparatus, procedures and evaluation so manufacturers and testing laboratories can produce consistent, comparable results.
Key topics and technical requirements
- Test principle: A leather specimen and a standard test fabric are separately immersed in a 30 g/L sodium chloride solution, then pressed together under a controlled pressure and temperature to simulate saltwater exposure and transfer. After drying, colour change and staining are evaluated against grey scales.
- Apparatus & materials: stainless steel test frame with a ~5 kg rectangular weight (≈115 × 60 mm) applying 12.5 ± 1.0 kPa; plates of inert material (glass/acrylic); oven at 37 ± 2 °C; vacuum container reaching ~5 kPa; ISO-specified test fabrics (multifibre or single-fibre references); fine abrasive paper (P180).
- Specimen preparation: typical specimen sizes ~100 × 40 mm; optional removal of surface finish by abrasion (procedure described) with the requirement to record if finish was removed.
- Procedure parameters: immersion with vacuum cycles, preheated weight, pressing composite in oven for (180 ± 10) min at 37 °C, followed by air drying before evaluation.
- Evaluation & instrumentation: visual assessment under D65 illuminant using ISO grey scales (ISO 105‑A02 for colour change and ISO 105‑A03 for staining) or instrumental measurement (spectrophotometer / colorimeter) per ISO 105‑A04 / A05 when results are uniform.
- Reporting: required items include reference to ISO 25089:2025, leather description, finish removal status, grey-scale ratings for staining by fibre type and for colour change.
Applications and users
- Quality control in tanneries and leather finishing operations to verify saltwater fastness of finished leathers or leather after finish removal.
- Footwear, marine upholstery, automotive and outdoor leather product manufacturers assessing durability for saltwater exposure.
- Independent testing laboratories performing compliance testing, supplier qualification, and product development (R&D).
- Specification writers and procurement teams requiring objective test data for contracts or performance claims.
Related standards
- ISO 7906:2022 (general principles for leather colour fastness tests)
- ISO 2418 (specimen location and preparation)
- ISO 3696 (laboratory water quality)
- ISO 105‑A02 / A03 / A04 / A05 and ISO 105‑F01…F10 (grey scales, instrumental methods and reference fabrics)
ISO 25089:2025 is essential for consistent assessment of saltwater colour fastness in the leather industry and integrates with established textile and leather testing standards for reliable, reproducible results.
