Classification of pigments

Pigments may be classified on different bases, such as color, chemical nature (inorganic or organic) and process of manufacture (synthetic or natural). A few of such classifications are explained below. 

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The concept of particles and particle shape corresponds to that used in the recommended and internationally accepted classification of pigment particles given in [1.9] (see Fig. 1 and Table 5). 

The classification of pigments and extenders used for further discussion is shown in Table 7.3 and certain description and properties of each class are generalized as follows ... 

An application-oriented classification of pigment blacks distinguishes between High Color (HC), Medium Color (MC), Regular Color (RC) and Low Color (LC) pigment blacks. A third capital letter relates to the manufacturing process furnace black process (F) or gas black process (C, from the historically similar channel black process). 

Dimeric pre-anthraquinones probably are formed by initial phenolic coupling of two dihydroanthracenone units. The sites in the respective aromatic nucL i at which this coupling occurs form the basis for the classification of pigments followed below. 

This body has devised a scheme for the classification of pigments, based on the chemical and structural identity of the colouring substance. It excludes single metal oxides and non-oxide pigments (q.v.) but includes all mixed metal oxides in one of 14 crystal classes and over 50 pigment categories, each having a specific DCMA Number (E.g. Crystal class XIII is spinel and DCMA No 13-26-2 refers to cobalt aluminate blue spinel. 

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