26 декабря, 2015 
Pokraskin Metallic, pearlescent and fluorescent pigments are grouped together in this section as three types of pigment used for their ability to produce unusual optical effects.
By far the most important metallic pigment is aluminium flake, C. I. Pigment Metal 1. The use of aluminium pigments to provide the commonly-observed metallic effect in car finishes is well known, and they are used also in a range of printing ink and plastics applications. The pigments owe their importance to the highly reflective nature of aluminium metal and their stability, which is largely due to the thin, tenacious oxide film on the surface of the pigment particles. Aluminium pigments are generally manufactured from aluminium metal by a wet bafimiHing process in the presence of a fatty acid (usually stearic or oleic) and a mineral oil. The presence of the liquid ingredients is essential to improve the efficiency of the process and to eliminate the potential explosion hazard of dry grinding. Aluminium pigments consist of small lamellar particles. The pigments are categorised according to their ability to ‘leaf’. Leafing grades when incorporated into a film become oriented in a parallel overlapping fashion at or near the surface of the film, thus providing a continuous metallic sheath and a bright silvery finish. Nonleafing grades are distributed more evenly throughout the film producing a sparkling metallic effect.
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