Color Index

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The Color Index ( CI for short ) is a reference work that has existed since 1925 for all common colorants and dye-based chemicals and is considered a standard work in the field of pigment and dye chemistry.


The Color Index is published by the British Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists . This work contains information about the chemical structure and common names of colorants , but also about synthesis , reaction behavior , solubility and patent literature . Inclusion in the Color Index is made on a voluntary basis by the manufacturers, who usually do not publish the chemical structure themselves. The chemical structure of many colorants that have a color index is not publicly available.


The Color Index generally differentiates between dyes and pigments .

CI Generic Name

The CI Generic Name is formed as follows:

CI Class name Color designation Consecutive number modification
example 1 CI pigment Red 254
Example 2 CI pigment Blue 15th :1

Class name

The colorants are divided into the following categories. All classes except the pigments are dyes, whereby the term “dyes” is omitted in the CI Generic Name .

designation Short Explanation
acid A. Acid dyes
basic B. basic dyes
Direct D. Direct dyes
Mordant M. Mordant dyes
Sulfur Sulfur dyes
Azoic Azo dyes
Reactive R. Reactive dyes
Vat V Vat dyes
Solvent S. water-insoluble dyes
Food F. Food coloring
Disperse DS Disperse dyes
Natural N Natural dyes
pigment P Pigments

Color designation

The following can be used as the color designation:

Current number

Within these groups, newly discovered colorants are numbered consecutively, i. H. newer coloring agents have a higher number within their group.


With some pigments, there is also a distinction between various modifications (for example with phthalocyanine blue , CI Pigment Blue 15) or laking cations (with laked pigments, e.g. BCI Pigment Red 48). In the example, the modifications of CI Pigment Blue 15 listed in the Color Index are compared.

CI Generic Name Explanation
CI Pigment Blue 15 non-modification-stabilized quality
CI Pigment Blue 15: 0 α-modification, not stabilized against modification changes
CI Pigment Blue 15: 1 α modification
CI Pigment Blue 15: 2 α-modification, stabilized against flocculation
CI Pigment Blue 15: 3 β modification
CI Pigment Blue 15: 4 β modification, stabilized against flocculation
CI Pigment Blue 15: 6 ε modification


Food colors have their own CI Generic Name . Patent blue V Na salt ( E 131 ) is called Acid Blue 3 . In food grade, the same dye is called Food Blue 5 (!).

CI Constitution Number

In addition to the CI Generic Name, there is a division according to the so-called CI Constitution Number . Due to their chemical properties, the colorants are sorted into five-digit numbers and, since 1997, into six-digit numbers according to the following system. This number (table above) can be used to make rough statements about the chemical characterization of the dyes and pigments .

It should be noted that every colorant contained in the Color Index has a CI Generic Name , but not necessarily a CI Constitution Number .

The CI Constitution Number is used in official ordinances, for example in the ordinance on cosmetic products (Switzerland) .

To correctly name a colorant according to the CI Constitution Number , it is sufficient to prefix the number with the abbreviation CI .


group Number range group Number range
Nitroso 10000-10299 Nitro 10300-10999
Monoazo 11000-19999 Disazo 20000-29999
Triazo 30000-34999 Tetrakisazo 35000-35999
Polyazo 36000-36999 Azo 37000-39999
Stilbene 40000-40799 Carotenes 40800-40999
Diphenylmethane 41000-41999 Triaryl methane 42000-44999
Xanthene 45000-45999 Acridine 46000-46999
Quinoline 47000-47999 Methine 48000-48999
Thiazole 49000-49399 Indamine 49400-49699
Indophenol 49700-49999 Azine 50000-50499
Azaheterocycles 50500-50999 Oxazine 51000-51499
Benzoxazole 51500-51999 Thiazines 52000-52999
sulfur 53000-54999 Lactones 55000-55999
Amino ketones 56000-56999 Hydroxyketones 57000-57999
Anthraquinone 58000-72999 Indigoid 73000-73899
Quinacridone 73900-73999 Phthalocyanine 74000-74999
Natural dyes 75000-75999 Oxidation bases 76000-76999
Inorganic pigments 77000-77999


Common name CI Constitution Number CI Generic Name CAS number Color example
aniline CI 76000 CI oxidation base 1 62-53-3 Colorless
Berlin blue CI 77510 CI Pigment Blue 27 14038-43-8  
Bismarck Brown Y CI 21000 CI Basic Brown 1 10114-58-6  
Quinacridone CI 73900 CI Pigment Violet 19 1047-16-1  
Fluorescein CI 45350 CI Acid Yellow 73 2321-07-5  
indigo CI 73000 CI Pigment Blue 66 482-89-3  
Calcium sulfate dihydrate CI 77231 CI Pigment White 25 10101-41-4  
Patent blue V , E 131 CI 42051 CI Food Blue 5 20262-76-4  
Patent blue V , sodium salt CI 42051 CI Acid Blue 3 20262-76-4  

The classification according to the Color Index is independent of the CAS classification . The Color Index is used in pigment and dye chemistry and across all brand names in the pigment and dye industry, especially the CI name is the usual way of designating characterization. The theoretical CAS number , like the IUPAC nomenclature, is not used in the colorant area.

Web links

Individual evidence

  1. DIN 55944 . In: German Institute for Standardization e. V. (Ed.): Colorants 1 . 7th edition. DIN-Taschenbuch 49.Berlin, Vienna, Zurich 2012, ISBN 978-3-410-23202-5 , pp. 522 .
  2. ^ British Society of Dyers and Colourists
  3. ^ American Association of Textile Chemists and Colorists
  4. ^ Chemical Constitutions in the Color Index Society of Dyers and Colourists & AATCC. Retrieved July 15, 2016.
  5. Ordinance on cosmetic products (PDF; 162 kB).