Effect pigments

Effect pigments are specially developed particles that are used in coating systems – particularly in automotive paints, plastics and cosmetics – to create visual effects such as gloss, colour change (chroma shift) or depth. Unlike classic colour pigments, effect pigments do not primarily work through absorption, but through reflection, refraction and interference of light.

A typical example are mica-based effect pigments, in which fine mica flakes are coated with wafer-thin layers of silanes, metal oxides or metals such as titanium, iron or aluminium. These coatings produce iridescent, metallic effects. In automotive paints, they produce changing colours depending on the incidence of light – for example, from black to dark green or from violet to blue.

The production and processing of these pigments requires the utmost care. The flake-like structure – for example, of the mica particles – must not be damaged or bent during mixing, as this would significantly impair the optical effect. amixon^® mixing systems enable gentle and highly precise homogenisation of these sensitive pigments. In a first step, the pigments are often silanised in a powder bed – a very thin, even coating produced by a chemical reaction in a dry state.

Effect pigments can also be based on other substrates, e.g. aluminium flakes or synthetic substrates such as glass or silicon dioxide. These pigments produce effects such as pearlescence, metallic or hologram effects.

In practice, effect pigments are first mixed in powder form and then transferred to a liquid medium, e.g. for the formulation of dip or spray coatings. The quality and uniform distribution of the pigments in the powder mixing process have a decisive influence on the subsequent appearance of the coating.