Optically variable ink
Optically variable ink also called color shifting ink is an anti-counterfeiting measure used on many major modern banknotes, as well as on other official documents.
The ink displays two distinct colors depending on the angle the bill is viewed at. The United States fifty-dollar bill, for example, uses color shifting ink for the numeral 50 so that it displays copper at one angle and bright green in another.
OVI is particularly useful as an anti-counterfeiting measure as it is not widely available, and it is used on security printing. One major manufacturer is a Swiss company called SICPA. Additional suppliers include German company Gleitsmann Security Inks, Sun Chemical, the Brazilian company Sellerink, located in São Paulo, Brazil and the Swiss company Printcolor Screen AG, located in Berikon, Switzerland.
Color-shifting inks reflect various wavelengths in white light differently, depending on the angle of incidence to the surface. An unaided eye will observe this effect as a change of color while the viewing angle is changed. A color copier or scanner can copy a document only at one fixed angle relative to the document's surface. It uses finely powdered pearlescent glitter.Optically Variable Magnetic Ink , also called as SPARK has visual effects that are based on the magnetic properties of an optically variable magnetic ink. When the document is tilted, the effect of a bright light stripe movement occurs and the colour changes. Usually printed by screen printing.
That type of ink is used for Euro, Brazilian real and Russian ruble banknotes.
