Optical variable inks (OVI) and iridescent inks are made with pigments that show up as two different colours when viewed from contrasting angles. The usual colour pairs are red-green, gold-silver and green-blue. OVI is considered to be the best type of ink to prevent document forgery as it is so complicated to reproduce – copiers and scanners cannot replicate the colour change effect.
Used for
Authentication
Anti-tampering / Anti-alteration
Suitable for
Very small products
Small products
Medium-sized products
Large products
Goes on
Product
Packaging
Can be used for
Physical products
Visibility
Visible
Reading device needed
No
Connection to server
No
Description
The inks in this category work by reflecting the various wavelengths of the visible light spectrum differently, depending on the angle at which they hit the surface. When looking at the ink from different angles, the human eye perceives this effect as a change of colour. As colour copiers or scanners copy a document at a fixed angle relative to the document’s surface, they can reproduce only one of the colours seen by the human eye.
A similar effect is obtained with iridescent inks. These are special pearled, pearlescent or mother-of-pearl inks that contain transparent pigments composed of thin mica particles. When viewed from different angles, the colour intensity of these inks appears to change.
Uses
OVI and iridescent inks are mostly used on banknotes, official documents, such as professional licence certificates, and on paper valuables in general.
Implementation
If you want to use OVI or iridescent inks, you may need to adapt the printing stage of your production process. This will depend on how and where you apply the ink and what the desired effect is.
Cost
It is difficult to give a general idea of the costs associated with inks in this category as they vary significantly according to which is ink used, how and where. That said, it is worth noting that OVI can be a very expensive ink and is generally used only in small areas of a document to mark emblems, identity marks, etc.