What is color index name?

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I have understood that there is a need for an explanation of how different color pigments are described using a combination of letters and numbers. Below is a brief description of the system called The Colour Index Generic Name Code.

Two organizations are responsible for this system: the Society of Dyers and Colourists from the UK and the American Association of Textile Chemists and Colorists in the USA. They have developed and maintain two systems:

• The Colour Index Constitution Number is a system that classifies dyes and pigments based on their chemical structure.
• The Colour Index Generic Name is a system in which each pigment is described with letters representing its color, followed by numbers.

It is the Colour Index Generic Name (CIGN) that artists use to navigate the complex world of different pigments. In my articles on watercolor paints, I refer to it as the “Colour Index” or “Colour Index Name.” This system makes it possible to describe which pigment or pigments a particular paint is made from. However, for a more detailed description of a pigment’s properties, other resources must be consulted. For those interested, I recommend the following resources:

• https://www.handprint.com/HP/WCL/waterfs.html
• https://artistpigments.org/pigments
• https://www.artiscreation.com/Color_index_names.html

A Colour Index Name consists of letters indicating the color of a given pigment. An example: a red pigment is designated PR, which stands for Pigment Red. The letters are followed by one or more numbers that distinguish a specific red pigment from other red pigments. This system is only used to define pigments; it does not describe any of their properties.

Natural and organic dyes use N (natural) instead of P, so, for example, indigo is designated NB1, and madder lake is NR9. Furthermore, P (pigment) can be replaced by D (dye) if it concerns a soluble dye.

Summary

A specific Colour Index Name only indicates which pigment or pigments a particular paint is made from; it does not provide any information about the color’s properties. If you find that a color called Cobalt Blue contains the pigment PB28, you must then look up additional information about its properties if you are interested. If you were to discover that the same color is made with PB29 + PW6, you would know that the manufacturer has adulterated your paint with other, cheaper pigments.