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    Think Different. Making Security Features More Secure.

    The importance of a holistic approach to banknote security and design.

    As an industry we focus a lot on the individual banknote components. Yet the end users see an entire banknote and innovation also comes from the integration of components into that banknote. When a banknote is exchanged people tend to glance at it for only a fraction of a second and perception studies tell us that people see banknotes holistically in those moments. This article examines why it’s important to think holistically about security features and consider the essential role that integration also plays in unlocking the next wave of innovation.


    The pros and cons of disaggregating banknotes

    Central banks used to simply source their entire banknote from a single supplier, but over the past decade banknote procurement has become more disaggregated, with substrate and security features often being sourced separately. The disaggregated approach means that banknote designers and manufacturers need to be highly skilled at integrating multiple components into a banknote (including components from other suppliers). The final banknote needs to meet the durability, sustainability and cost requirements of the central bank whilst also being secure, functional, easy-to-manufacture and aesthetically pleasing. 

    This disaggregated approach encourages competition around component technology and increases central bank choice about their preferred combination of substrate and security features. However, it can also introduce complexity, spoil levels and cost for those involved and impacts innovation in ways that may not be immediately obvious.


    Component-driven innovation

    In a disaggregated model the value tends to flow towards the components manufacturer instead of the integrator, which drives an industry research and development focus on the components. This encourages competition and ultimately leads to more advanced components. For instance, it has led to combinational threads such as IGNITE®, which utilise the strengths of multiple technologies instead a single technology, with competition then driving IGNITE® towards stronger and more impactful effects. It has also driven the latest range of “holographic” foil effects, such as PUREIMAGE™ and SPOTLIGHT™, which use advanced surface-relief micro-structures that go beyond standard holographics. 

    The disaggregated approach towards banknote procurement also advances banknotes through manufacturers finding innovative and creative ways to integrate components they didn’t develop. The components may not have been optimised for the make/model of manufacturing equipment of the integrator and they may not be immediately compatible with the other products of the integrator. This means that the integrator invests time, effort and sometimes capital in new equipment to manufacture banknotes incorporating components from other suppliers. Over time this further increases the integrator’s expertise in processes and banknote design. 

    However, if we drive the value towards components and the cost towards the integrator then mainly focus research and development efforts on component-driven innovation (either directly via the component or indirectly through innovating to work out how to incorporate the component) we risk missing the pure integration-driven innovation. Going forward there is a need for both.


    Integration-driven innovation

    Security threads are an early example of integration-driven innovation. The thread itself provides some security. However, it’s the integration of the thread into the banknote that makes it particularly secure. Forming the paper substrate around the thread to create a windowed thread in the substrate raises the barrier to simulation. A thread that is simply stuck onto the banknote would improve the banknote security but not to the same extent as one that is embedded. 

    The combination of the security feature and the integration approach helps to explain the success of threads over the decades: 96% of all circulating paper banknote designs have a security thread. 46% have an applied or printed optically variable effect in addition to a thread. Only 1% of paper banknotes were designed with an applied or printed optically variable feature instead of a thread. 

    The micro-optics embedded stripe NEXUS™ is another example of integration-driven innovation. NEXUS™ was developed due to a desire for a security thread where a larger area of the effect was visible. This innovation required creativity and progression, beginning with integration-led thinking that was different to what would have been achieved by focussing only on the technology. 

    Ultimately future banknotes will benefit if all types of innovation are valued, and the importance of integration-driven innovation is also recognised.


    Surface-Relief Micro-Structures progressing via component-led and integration-led innovation

    Holographic features (and variants thereof consisting of advanced surface-relief micro-structures) provide large areas of engaging effects and imagery. Their large area contributes towards the patch or stripe being highly visible and instantly recognised on a banknote. 

    De La Rue’s “holograms” today go far beyond standard holography and expand into a large suite of surface-relief micro-structures. They enable an object to be captured in full three-dimensions and this perception of strong image-based three-dimensional depth from Depth™ or stereographic TrueImage™ have never been simulated, with criminals often defaulting to a simple two-dimensional image. The complex switching effects where one character or image is replaced by another over the top of it has never been replicated. Our SPOTLIGHT™ effect, whereby two icons move above or below the plane of the hologram, has never been simulated. The dynamic movement of our PUREIMAGE™ effects have not be simulated. The grating structures that enable these “holographic” effects are very different from those achievable with commercially available machines. 

    Holograms are increasing in popularity as a security feature for polymer banknotes - in the past four years the number of polymer banknotes containing holographic foils has more than doubled. This in an area where innovation has been driven at both a component level and an integration level. For instance, SPOTLIGHT™ has advanced to allow two different icons to rotate above or below the plane of the hologram. In parallel the novel ways that the holographic foil has been integrated into the polymer window has also advanced.


    It's all about the windows for polymer banknote security features

    To understand the vital role of polymer windows in driving innovation for security features we’ll start by exploring their role as a standalone security feature.

    Easy to authenticate and difficult to simulate 
    Polymer windows represent a simple way to authenticate a banknote and come with a clear public education message. The large area of a window means it is a highly impactful feature so the presence (or absence) of a window is more binary and more obvious than that of a watermark. 

    Most polymer counterfeit notes are still produced on paper so can’t simulate the polymer windows convincingly and rarely pass as genuine notes. Modern polymer windows aren’t a simple shape and can’t be die-cut. And as the polymer window designs evolve they become more intricate, complex and engaging. 

    Deep design thinking
    In the rare event that a counterfeiter overcomes the challenges of sourcing and printing on polymer some of the depth of thought behind polymer window designs may be surprising. White ink forms part of the window to force additional counterfeiting steps – the photocopier sees the see-through window as being white and so loses the white ink detail upon copying. If this is overcome by putting something coloured behind the window there are then different process steps needed to stop the window being coloured. 

    Security is also built in by adding colour to the window, which requires perfectly registered white underneath. Specialist inks (such as the highly reflective silver ARGENTUM™) and security features (like ILLUMINATE™ or MASK™) add complexity and interactive elements that are hard to simulate.


    Security that is greater than the sum of its parts

    When a foil-based security feature is applied to a polymer window its effects become visible on both sides of the banknote, meaning that a single feature can help protect the entire banknote. However, using security features in the window of a polymer banknote is also important beyond the value-for-money element because integrating security features into a polymer banknote window requires specialist know-how and equipment. 

    Applying a foil to a polymer window is more complex and more beneficial to the banknote security than applying it to an opaque paper substrate or an opaque part of the polymer. This is because criminals can more easily simulate foils that are applied to an opaque surface. 

    Applied foils in polymer windows adopt intricate shapes and are carefully registered to the detail of the window. In contrast counterfeit foils are typically a sticker with noticeable edges (that can’t be felt on genuine holograms) or are applied by tape with some discolouration and haze. With polymer windows the foil is being stuck onto a see-through area, which means the adhesive will be visible (unlike the adhesive of foils being stuck onto a paper note). The adhesive may also need to work on the window as well as the printed part of the polymer substrate. These factors form multiple significant barriers to criminals attempting a convincing simulation. 


    Going beyond “holograms” and polymer windows

    “Holographic” foils continue to push the boundaries, enabling people of symbolic importance to be captured in full-three dimensions on a banknote whilst comprising multiple different security effects (each providing a different type of counterfeit resiliency). The effects go beyond standard holography, combining proprietary techniques, the latest IP and specialist know-how that continues to advance. Holograms are further enhanced on polymer, appearing brighter and sharper due to the smooth substrate surface.

    Polymer substrate contains multiple layers that combine with the banknote print, which means there are multiple layers and points of interaction to push the boundaries of design thinking and security feature integration. Polymer banknote design is moving towards notes with multiple windows and security features distributed over those windows. Historic designs were constrained to paper layouts and structure but this isn’t necessary going forward. Security features can increasingly be adapted to form part of an overall design with more fluid, customisable and complex shapes that offer stronger visual cues to support authentication. In this sense the aesthetic also contributes towards the security. Different advanced “holographic” effects can appear to be distributed across the banknote.

    The design and integration potential of polymer is significant. We’re only just starting to unlock what’s possible with polymer windows and central banks should expect to see security features and windows combining to create imagery and effects far beyond what a standard polymer banknote looks like today.