Cadmium pigments are stable inorganic colouring agents which can be produced in a range of brilliant shades of yellow, orange, red and maroon. Their greatest use is in plastics but they also have significant application in ceramics, glasses and specialist paints.
The pigments are based upon cadmium sulphide which produces a golden yellow pigment. Partial substitution of cadmium in the crystal lattice by zinc or mercury, and of sulphur by selenium, forms a series of intercrystalline compounds making up the intermediate colours in the lemon-yellow to maroon range of cadmium colours (Fig. 1). The pigments are fine, discrete particles of coloured powder, with diameters of around 1 gm, which are distributed and suspended in the material to produce a uniformly coloured product. Cadmium pigments have excellent heat stability which makes them essential in applications where elevated processing or service temperatures are encountered.