ISO 18451-2:2018

Overview - ISO 18451-2:2018 (Pigments, dyestuffs and extenders)

ISO 18451-2:2018 defines a standardized classification scheme for colouring materials used in industry and by consumers, organized by both colouristic (optical) and chemical aspects. It is Part 2 of the ISO 18451 series and relies on the terminology given in ISO 18451-1. The second edition (2018) is a minor revision that updates references, corrects typos and refines examples. The standard lists practical examples (with Colour Index designations where applicable) for inorganic and organic pigments and dyestuffs used across coatings, ceramics and selected food and ceramic dyestuff applications.

Key topics and technical content

• Scope & intended users: Applies to producers of colouring materials and end users who select or specify them.
• Normative references: Terminology and definitions are taken from ISO 18451-1.
• Classification by colouristic aspects: Grouping based on optical behaviour, e.g.
  • White pigments (light scattering; e.g., titanium dioxide Pigment White 6)
  • Coloured pigments and dyestuffs (wavelength‑dependent absorption; examples include iron oxides, phthalocyanine blues)
  • Black pigments (broad absorption; e.g., carbon black)
  • Effect pigments (metallic, nacreous, interference effects)
  • Luminous pigments (fluorescent and phosphorescent)
• Classification by chemical aspects: Separation into inorganic and organic colouring materials, with subcategories and representative examples and Colour Index entries.
• Tables and examples: Comprehensive tables listing pigments/dyestuffs (e.g., titanium dioxide, carbon black, phthalocyanine blue, quinacridone pigments) and Colour Index numbers to aid cross‑reference.
• Notes and limitations: Some inorganic dyestuffs for enamel, glass, ceramics and food are provided as examples but are not exhaustively classified within the committee’s scope.

Practical applications - who uses ISO 18451-2

• Material manufacturers - product classification, cataloguing and labelling.
• Formulators and R&D teams - selecting pigments/dyestuffs by optical or chemical properties.
• Quality assurance and procurement - specifying materials consistently across supply chains.
• Regulatory and compliance teams - harmonizing product descriptions and documentation.
• Ceramics, coatings, plastics and selected food industry users - reference for matching performance and appearance requirements.

Related standards and references

• ISO 18451-1 - Terminology: general terms for pigments, dyestuffs and extenders (normative reference).
• The Colour Index - widely used reference for Colour Index designations (referenced in the standard as a practical cross‑reference).

ISO 18451-2:2018 is a practical classification tool for consistent communication about colouring materials, supporting specification, selection and quality control across pigment and dyestuff supply chains.