The Colour Index International is the authoritative classification of synthetic dyes and pigments, first published by the Society of Dyers and Colourists in 1924 and continuously maintained since. It is the working reference for every industry that depends on precise, comparable colour — from textiles and coatings to inks, plastics, cosmetics, and the conservation of cultural heritage.
What the Colour Index is
Every commercial colourant in regular use is classified here under two identifiers: a Colour Index Generic Name (CIGN), which describes the colourant by application class and hue family, and a Constitution Number (CICN), which fixes the underlying chemistry. Together they let formulators, regulators, and researchers speak unambiguously about the same substance — even when manufacturers market it under a dozen different trade names.
The Fourth Edition Online consolidates the four print editions (1924, 1956, 1971, 2002) into a single live database. It currently holds:
- over 27,400 Generic Names across the dye and pigment application classes;
- more than 140,000 registered commercial products;
- submissions from 840+ manufacturers and suppliers worldwide.
How the publication is organised
The Index has historically been published in two parts, and the database preserves that structure:
- Part 1 — pigments and solvent dyes used in paint, plastics, printing-ink, and related industries; entries carry verified manufacturer and supplier data.
- Part 2 — the dye application classes (acid, basic, direct, disperse, food, fluorescent brightener, mordant, reactive, sulphur, vat); entries are confirmed or carried-over from the previous edition.
Each Generic Name carries a fingerprint — a structured record of chemical class, hue family, fastness ratings, regulatory inventory listings, and the commercial products registered against it. The fingerprint is the canonical identity the rest of the database hangs off.
The Society of Dyers and Colourists
The Index is the central publication of the Society of Dyers and Colourists (SDC), a registered educational charity based in Bradford, West Yorkshire. The Society was founded in 1884 to put the rapidly expanding chemistry of synthetic colour on a rigorous footing — the years between Perkin’s discovery of mauveine (1856) and the formation of the SDC had produced a chaos of trade names, contested patents, and incompatible fastness ratings. Granted a Royal Charter in 1971, the SDC sets the standards by which dyes and pigments are named, tested, and traded internationally.
How the database is curated
Editorial oversight sits with the SDC editorial board and the Nomenclature Committee, which meets quarterly. New Generic Names and Constitution Numbers are proposed by committees of dye chemists drawn from industry, academia, and the regulatory community; each proposal is reviewed for chemical accuracy, fastness data, and lack of confusion with existing entries before publication. Commercial product submissions carry a binding supplier declaration; the SDC does not independently test commercial products, but each submission is checked against its registered fingerprint before it appears in search results.
How to cite a Colour Index entry
The standard citation format is the Generic Name, the Constitution Number, and the edition. For example:
C.I. Acid Red 1, C.I. 18050, Colour Index™ Fourth Edition Online (Society of Dyers and Colourists, 2026).
For commercial products, also cite the manufacturer’s trade name and the date you retrieved the record. The citation guide has the full template, including the API access form for downstream applications.
Who uses the Index
The Colour Index is consulted daily by:
- Textile and apparel manufacturers — specifying dyes by fastness and substrate.
- Paint, coatings, and printing-ink formulators — selecting pigments by hue group and physical form.
- Plastics, cosmetics, and food-colour producers — resolving regulatory status and inventory listings.
- Heritage and conservation scientists — tracing a historical dye to its modern equivalent or its retired predecessor.
- Toxicologists and regulators — resolving CAS numbers and substitution chains.
- Academics, students, and libraries — the SDC’s charitable mission specifically supports educational access.
Partner organisations
The Colour Index is published in partnership with AATCC (the American Association of Textile Chemists and Colorists), the world’s leading not-for-profit association serving textile professionals across more than sixty countries. Beyond AATCC we collaborate with several specialist bodies whose remit overlaps with the Index:
- CPMA (Color Pigment Manufacturers Association) — the trade body for pigment manufacturers across North America. CPMA contributes to the pigment record set and verifies product listings for the Part 1 entries.
- ETAD (Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers) — founded 1974 to coordinate the industry’s response to health and environmental regulation. ETAD’s code of ethics and regulatory cross-references feed our toxicology metadata.
- CDIA (China Dyestuff Industry Association) — established 1985, with 220+ members across master batches, organic pigments, and textile-printing auxiliaries. CDIA contributes to the Asian manufacturer record set.
- Biological Stains Commission — the independent testing body that certifies dyes used in histology and microscopy. Its certifications are surfaced on the relevant Generic Name records.
We also work closely with national chemical-inventory authorities to maintain CAS, EINECS, and ELINCS cross-references.
Editions and history
The first edition (1924) brought together the scattered naming conventions accreted since the 1860s. The second (1956) added the post-war boom in synthetic dyes. The third (1971) introduced the Constitution Number as a chemistry-grounded counterpart to the Generic Name. The fourth (2002, online since 2006) folded the print supplements into a continuously-updated digital edition. The current platform — v3, launched 2026 — rebuilds the online edition as a live database with structured fingerprints, fastness data, and a public read API.
Retired Generic Names, alternative numbering schemes from the print editions, and the narrative notes from earlier volumes are preserved in the Heritage archive, which links each historical entry to its modern equivalent where one exists.
Subscriptions and access
Individual, company, and university subscriptions are available, with discounted academic pricing supporting the Society’s charitable mission. Search, hue navigation, and the Generic Name index are open to all visitors; full fingerprint data, the commercial product roll, and the public API require an active subscription.
Get in touch
For editorial enquiries, subscription support, manufacturer registration, and commercial licensing, see the Contact page. The SDC operates from Perkin House, 82 Grattan Road, Bradford BD1 2JB, United Kingdom. The Society of Dyers and Colourists is a registered charity in England and Wales (No. 212331).