Overview
ISO 105-N03:1993 - Textiles: Tests for colour fastness - Part N03: Colour fastness to bleaching: Sodium chlorite (mild) specifies a laboratory method to determine how resistant textile colours are to mild bleaching with sodium chlorite as used in textile processing. The method is intended primarily for textiles of natural and regenerated cellulose (and related fibre types referenced in the document). The test exposes a specimen in contact with one or two specified adjacent fabrics to a controlled sodium chlorite bath, then assesses colour change and staining using the grey scale.
Key topics and technical requirements
- Test solution: Sodium chlorite solution nominally about 1 g/L, adjusted to pH 3.5 immediately before use; concentration is verified by titration (thiosulfate).
- Apparatus: Glass vessel with a reflux condenser or equivalent to minimise evaporation and maintain bath composition.
- Specimen assembly: The specimen is mounted in contact with either a multifibre adjacent fabric or two monofibre adjacent fabrics (dimensions typically 40 mm × 100 mm) as specified.
- Conditions:
- Bath temperature: 80 °C ± 2 °C
- Time: 1 hour
- Bath ratio: 50:1
- Post-treatment: Rinse (10 minutes under cold running water), open the composite specimen (unsew three sides), and dry suspended at temperatures not exceeding 60 °C.
- Assessment:
- Evaluate colour change of the specimen and staining (crocking / transfer) onto adjacent fabrics using ISO grey scales (ISO 105‑A02 and ISO 105‑A03).
- Reporting requirements: Include standard reference (ISO 105‑N03:1993), sample identification, colour change grade, staining grades per adjacent fibre type, and details of test conditions and adjacent fabrics used.
Applications and users
This standard is used for:
- Quality control and incoming inspection in textile manufacturing and dye houses
- Process development and optimisation where mild bleaching (sodium chlorite) is applied
- Supplier verification, product specification and compliance testing for garments and home textiles
- Laboratory testing services, certification bodies, and R&D teams assessing colour fastness and chemical process effects
Keywords: ISO 105-N03:1993, colour fastness, sodium chlorite, mild bleaching, textiles, grey scale, multifibre, monofibre, cellulose.
Related standards
- ISO 105-A01 (general principles)
- ISO 105-A02 (grey scale for degradations)
- ISO 105-A03 (grey scale for staining)
- ISO 105-F / ISO 105-F10 (adjacent test fabrics, multifibre specifications)
This concise guide helps technicians and procurement teams understand when and how to use ISO 105‑N03 to assess textile colour stability under mild sodium chlorite bleaching.