Metallic Ink
Ink containing a fine-dispersed metal powder. It has a specific metallic gloss. Only gloss intensity changes when changing the angle of observation and illumination of the image applied in metallic ink. No significant changes in color are observed. Metallic inks look dark in IR light.
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Fig. 1. Estonia. Alien's passport issued in 2014:
a — front endpaper. Paper substrate; b — the same. The coat of arms elements are applied in metallic ink of gold color; c — the same. Front endpaper. IR light
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b
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Fig. 2. New Zealand. Diplomatic passport issued in 2016:
a — page 27. Paper substrate; b — the same. Fragment of the see-through register applied in metallic ink of silver color; c — the same. In the bottom right corner, the see-through register looks dark on a light background. IR light