Cross referencing between foil element, print, substrate and security thread is the key to a modern and secure banknote.

Christoph Gebauer, Senior Product Manager High Security Foils at Louisenthal

“Another great thing about the laminate sealing layer is that it opens up a lot of opportunity for central banks to be creative,” comments Christoph Gebauer, Senior Product Manager High Security Foils at Louisenthal. “Cross referencing between the print, the thread and a foil element with a range of attractive structures (e.g. micromirrors, holograms) and colour effects (e.g. ColourShift, ColourChange) is the key to a modern banknote. Both the complexity and the attractiveness naturally add to the banknote’s resistance to counterfeiting.” Especially as any attempt to photocopy a note with a varifeye window in it just makes the optical effects of the copy appear completely different.

This amazing technology is the result of long years of research and development by Louisenthal’s top-flight scientists and engineers. And the production machines have all been custom-built too. All high tech made in Germany.

Front-to-back verification: The image colour changes from gold to an intensive blue as the light shines through the windows, making verification easier.

Highly secure with layered front-to-back design elements embedded in the banknote paper.

What are the smart window’s main advantages?


  • Easy to recognise and authenticate at a glance
  • Brilliant, dynamic, and bright effects
  • Exclusive production process makes it very difficult to forge
  • Decorative features applied to the smart window also heighten security
  • Broad scope for creativity with the addition of strikingly colourful effects, holograms and printed designs for cross referencing on the banknote
  • The window shape can be customised to harmonise with other design elements
  • A unique, multi-faceted foil feature connects the front and back of the note, making forgery very difficult
Versatile foil applications for breathtaking results

Customers can choose the application method depending on their manufacturing set-up. For example, the secure windows can be applied from roll to roll or directly onto a stack of pre-cut sheets, with or without a printed background.

You also have the flexibility to use secure windows delivered as a foil element or as a pre-punched patch. Or save time by ordering the complete solution: the substrate that already includes the secure windows with the window-foil element on them, combined with a wide range of additional security features like threads, fluorescence and hidden, machine-readable security elements.

varifeye® ColourChange (Stripe)


Even in low-light conditions, varifeye ColourChange shines in sophisticated gold with motion effects and glistening micromirrors on the front and back of the banknote in reflection. varifeye ColourChange has a custom-shaped window in the paper – and when you hold the banknote up to the light the colour turns from gold to deep blue in transmission. Combined with the precision-cut security window, banknote designers and central banks can create designs that offer maximum security and visual impact. The feature is visible from both sides of the banknote and it offers you a generous area of effects – even with silver coloured elements.

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varifeye® ColourChange Patch


The patch brings it all together: colour, gloss, glistening micromirrors and other aesthetic effects. It’s a stunning piece of art – but also offers Louisenthal’s unique front-to-back security technology. As with varifeye ColourChange, the patch on the window changes colour from gold in reflection to blue in transmission, making it very easy to recognise and authenticate but very hard to forge. You can create an individual patch shape and a custom-shaped window, which is visible from the back and in transmitted light. The patch offers a maximum of design freedom. Besides of the shape and the effects, you can place and integrate it very individual on the banknote. This varifeye ColourChange Patch will support the story of your banknote in a persuading way.

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