Optically Variable Ink (OVI)
OVI – Optically Variable Ink
An ink, containing optically variable pigments which change colour depending on the angle of light incidence and view. Applied by intaglio or screen printing.
It is important for colours to be contrasting and well distinguishable (fig. 1).
a
b
Fig. 1. Optically Variable Ink (OVI). 500 Euro (2002):
a – view at right angles; b – view at an acute angle