Traditionally, decorative pigments produced using vacuum roll coating processes rely on the interaction of light with one or more layers of the pigment flake structure to produce color-shifting effects. By controlling the physical dimensions and surface microstructure, it is possible to create pigments that utilize the diffractive interference rather than thin film interference to create novel optical effects. The resulting pigment appearance can be characterized to have a silver base color with a diffractive rainbow effect that appears to emanate from the surface in pleasing and subtle tones. This paper will discuss the structure, manufacture and physical properties of diffractive pigment flakes.
The phenomenon of light interference can be produced using thin film or diffraction technology. Color-shifting pigments, ranging from micas to highly engineered, multi-layer pigment flakes, all based on thin film light interference, have been used in the marketplace for a number of years.