IRIDESCENT INK

Semitransparent ink with pearl luster caused by an interference structure of a thin film. The ink contains scaly mica pigments covered by a thin film of titanium dioxide (TiO₂), ferric oxide (Fe₂O³) or other metal oxides. When falling on pigments, one part of light is reflected, the other part is transmitted into the underlying layers. As a result, multiple reflection and transmission of light by different layers occur and result in interference. The luster is almost unnoticeable at a right angle of observation and illumination. When changing the angle of observation or illumination, the intensity of luster and the hue slightly changes.

a — Paper substrate; 

b —  Zoomed fragment. Iridescent ink. View at a right angle of observation and illumination; 

c —  Zoomed fragment. Iridescent ink pigments

a —  Front side. Paper substrate; 

b —  The letters JPN printed with iridescent ink. Oblique light; 

c —  Zoomed fragment. Iridescent ink pigments