There are fundamental differences between dyes and pigments which are best explained by the definitions below. These definitions have been agreed internationally through various organisations and we thank ETAD and CPMA for allowing us to use these.

ETAD defines dyes as

Dyes are intensely colored or fluorescent organic substances only, which impart color to a substrate by selective absorption of light. They are soluble and / or go through an application process which, at least temporarily, destroys any crystal structure by absorption, solution, and mechanical retention, or by ionic or covalent chemical bonds.

Kindly reproduced by permission of ETAD – The Ecological and Toxicological Association of Dyes and Organic Pigment Manufacturers.

ETAD seeks to base its positions on sound science and to coordinate the efforts of its members to minimize any possible adverse impact of organic colorants on health and environment. Member companies are obliged to adhere to the ETAD Code of Ethics, which is based on the principles of responsible care.

It has a representative on the Colour Index Technical Boards.

Further information on ETAD is available from their web site

CPMA defines pigments as

Pigments are colored, black, white or fluorescent particulate organic or inorganic solids which usually are insoluble in, and essentially physically and chemically unaffected by, the vehicle or substrate in which they are incorporated. They alter appearance by selective absorption and/or by scattering of light. Pigments are usually dispersed in vehicles or substrates for application, as for instance in the manufacture or inks, paints, plastics or other polymeric materials. Pigments retain a crystal or particulate structure throughout the coloration process.

Kindly reproduced by permission of CPMA – Color Pigment Manufacturers Association, Inc.

The Color Pigments Manufacturers Association, Inc. (CPMA) is an industry trade association representing color pigment companies in Canada, Mexico, and the United States. CPMA represents small, medium, and large color pigments manufacturers throughout Canada, Mexico and the United States, accounting for the bulk of the production of color pigments in North America. It has a representative on the Colour Index Editorial Board CIEB.

Further information on CPMA is available from their web site