SJH OVI optically variable ink gold to green color shift test: shifts between gold and green at different viewing angles - for banknotes, cigarette packs and premium brand protection.
A full written description of the demonstration, so the content is readable without playing the video.
This video demonstrates the gold-to-green colour shift of SJH OVI optically variable ink: the printed pattern switches between gold and green with viewing angle - the classic optical security solution.
The video first shows the printed pattern from the front, where it reads gold (yellow-green). OVI ink produces angle-dependent colour through multilayer thin-film interference. Unlike ordinary metallic pigments that only change in reflected brightness, its hue itself changes markedly with angle - the source of its security strength.
As the camera changes viewing angle the hue switches to green. The flip is most pronounced between front and oblique views, with a continuous colour transition. Colour copiers and scanners can only record a static image at one angle and cannot reproduce an angle-dependent shift - the fundamental reason OVI has long been a core security feature on banknotes and cigarette packs.
What the video shows is the OVI effect under screen printing. Optically variable ink is normally screen printed to achieve sufficient film thickness - too thin a film noticeably weakens the shift - so process parameters (mesh, film thickness, drying) strongly influence the result. This is why the same ink looks noticeably different when printed by different companies.
| Principle | Multilayer thin-film interference produces angle-dependent hue shift |
|---|---|
| Security logic | Copiers and scanners capture a static single-angle image and cannot reproduce the shift |
| Process | Usually screen printed to build film thickness; a thin film weakens the effect |
| Typical use | Banknotes, cigarette packs, wine labels, premium brand marks, card security |
OVI is one of the best combinations of public verifiability and high reproduction barrier in optical security: no equipment is needed, a consumer only has to tilt the package, while a counterfeiter would need multilayer thin-film optical materials and precision coating capability. Note that the effect depends heavily on film thickness and printing process, so confirm the final effect with an actual printed proof rather than judging from a colour chart alone.
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