The new SPECTRAL™ security feature

Orell Füssli Security Printing introduced SPECTRAL™, the new security feature for banknote windows at the Currency Conference 2017 in Kuala Lumpur.
The currency conference brings together a wide variety of security printing industry representatives, from national banks via security experts right up to ID security printers and their customers from all over the world. Aside from the very intensive presentation programme, the aim of the conference is to facilitate a lively and fruitful exchange between the specialists of the security branch. It was a good opportunity for Orell Füssli Security Printing to present itself once again in an international environment.

What is SPECTRAL™?

SPECTRAL™ is a new security feature for banknote windows. Photorealistic images in banknote windows are printed through offset processes with transparent UV fluorescent colours which are only visible under UV light. The name SPECTRAL comes from the two image aspects of the feature: the full-colour one visible under UV light (spectrum) and the greyscale image (spectre), which can be seen when the image is viewed in front of a dark background

How does SPECTRAL™ work?

In normal daylight or the right lighting conditions, the colours are transparent. You don't see anything. Fig. 1 shows the transparent window of a sample banknote which was printed on the Guardian® polymer banknote substrate. If the substrate is lit with UV light, the window shows a full colour picture (Fig. 2). A further greyscale image is visible in normal daylight if the window is laid against a dark background; because the transparent colours diffuse the light (Fig. 3). For the UV fluorescence effect to produce colourful images, a patented dynamic resolution method is used which is based on a diagonal orientation. This ensures that the colour of the colour overlay does not fade and no colour contamination occurs during the offset printing process.

Fig. 1: The window is transparent in front of a white background.
Fig. 2: A photorealistic colour image appears under UV light.
Fig. 3: A greyscale image is visible against a dark background.