Overview - ISO 105‑A03:2019 (Grey scale for assessing staining)
ISO 105‑A03:2019 is an international textile test specification that defines the grey scale for assessing staining (dégorgements) in colour‑fastness tests. It gives a precise colourimetric reference of the grey‑scale patches used to evaluate visual staining of adjacent fabrics and provides procedures to compare newly prepared working standards or standards that may have changed.
Keywords: ISO 105‑A03:2019, grey scale, colour fastness, textiles, staining, colourimetry
Key topics and technical requirements
- Purpose and scope: Description and use of the grey scale for assessing staining on adjacent fabrics in colour fastness testing.
- Scale formats: A 5‑degree base scale (indices 5, 4, 3, 2, 1) and an optional 9‑degree scale including intermediate half indices (4‑5, 3‑4, 2‑3, 1‑2).
- Colourimetric specification:
- White (first element) tristimulus Y = 85 ± 2.
- Defined CIELAB Δ (CIELAB colour‑difference) between adjacent pairs with tolerances:
- 5 → Δ = 0 (tolerance 0.2)
- (4‑5) → Δ = 2.2 ± 0.3
- 4 → Δ = 4.3 ± 0.3
- (3‑4) → Δ = 6.0 ± 0.4
- 3 → Δ = 8.5 ± 0.5
- (2‑3) → Δ = 12.0 ± 0.7
- 2 → Δ = 16.9 ± 1.0
- (1‑2) → Δ = 24.0 ± 1.5
- 1 → Δ = 34.1 ± 2.0
- Measurement method: Patches must be measured with a spectrophotometer including specular component; use ISO/CIE 11664‑1 (CIE 1964 10° observer) and illuminant D65 for colourimetric calculations.
- Assessment conditions:
- Place tested and original fabric samples side‑by‑side on a neutral grey surround (approx. Munsell N5).
- Illuminate with natural daylight (northern or southern daylight per hemisphere) or an equivalent source ≥ 600 lx; incident light ~45°, observation approximately perpendicular.
- Practical notes:
- Grey or black masking materials are permitted if consistently matched to test patches.
- The 5‑index “5” is assigned only when no perceptible difference is observed.
Applications and users
ISO 105‑A03:2019 is used to ensure consistent, repeatable visual grading of staining during colour fastness testing. Primary users include:
- Textile and apparel manufacturers (quality control)
- Dye, chemical and finishing labs
- Independent testing and certification laboratories
- Research and development groups working on dyes, finishes and washfastness
- Standards bodies and conformity assessment organizations
Practical benefits: standardizes visual comparisons, supports objective colourimetric verification of working grey standards, and improves repeatability across labs and suppliers.
Related standards
- ISO 105‑A01 - General principles for carrying out colour‑fastness tests
- ISO 105‑J03 - Calculation of colour differences for dye fastness tests
- ISO/CIE 11664 series (colorimetry, observers and calculations)
- CIE S‑017 (international lighting vocabulary)
For consistent testing, use ISO 105‑A03 in conjunction with other parts of the ISO 105 series and relevant colorimetry standards.