Overview
EN 20105-N01:1995 (identical with ISO 105‑N01:1993) specifies a laboratory test method for colour fastness to bleaching: hypochlorite. It defines how to determine the resistance of textile colours - mainly in natural and regenerated cellulose fibres - to bleaching baths containing sodium or lithium hypochlorite at concentrations used commercially. The method includes preparation of working hypochlorite solutions, specimen preparation, controlled exposure, neutralization/rinsing, and assessment of colour change using the ISO grey scale.
Key Topics and Requirements
- Scope and applicability: Primarily for natural and regenerated cellulose materials; applicable to textiles in all forms.
- Reagents and solutions:
- Sodium hypochlorite working solution: prepared from commercial NaOCl diluted to ≈2 g available chlorine/L, buffered at pH 11 ± 0.2 with anhydrous sodium carbonate (10 g/L).
- Lithium hypochlorite alternative: prepared from solid LiOCl to give ≈2 g available chlorine/L.
- Hydrogen peroxide or sodium hydrogen sulfite solutions for post‑treatment reduction.
- Specimen size and mounting:
- Fabric or knitted specimen: 40 mm × 100 mm (yarn or loose fibre guidance provided).
- Test conditions:
- Liquor ratio: 50:1 (solution to specimen).
- Temperature: 20 °C ± 2 °C.
- Exposure time: 60 minutes (avoid direct sunlight).
- Post‑treatment: thorough rinsing and agitation in specified reducing solution (e.g., hydrogen peroxide 2.5 ml/L or sodium hydrogen sulfite 5 g/L), then air dry ≤ 60 °C.
- Assessment:
- Colour change assessed with the ISO grey scale (ISO 105‑A02).
- Safety: Warnings on handling hypochlorite and hydrogen peroxide solutions; prepare hypochlorite solutions immediately before use.
- Test report must include standard reference, sample identification and the numerical rating for colour change.
Applications and Users
- Quality control and certification of dyed textiles for resistance to household and industrial bleaching.
- Textile manufacturers, dyers and finishers validating dye chemistry and process robustness.
- Independent testing laboratories performing colour fastness testing.
- Product development and R&D teams selecting dyes or treatments for cellulose-based textiles.
- Procurement and compliance officers verifying suppliers meet specified fastness performance.
Related Standards
- ISO 105‑A01: General principles of testing (referenced)
- ISO 105‑A02: Grey scale for assessing change in colour (used for evaluation)
- ISO 105‑C01: Colour fastness to washing (related methodology)
- EN 20105 series / ISO 105 series: other colour fastness parts
Keywords: EN 20105‑N01:1995, ISO 105‑N01:1993, colour fastness to bleaching, hypochlorite, sodium hypochlorite, lithium hypochlorite, textile testing, cellulose fibres, grey scale, colour fastness testing.