Security is the thread that binds us
When paper and thread meet in a banknote, it is about more than maximum security. At Papierfabrik Louisenthal, research, development, and production sit within walking distance of one another, so the site acts as an integrated system provider for security paper and threads. A conversation with Stephan Morgenstern, Head of Paper Production, and Patrick Engelmann, Project Manager Technologies, Threads & Foils, about how know-how and efficiency come together in modern security threads.
When it comes to embedding the thread in the paper, what challenges do you face today?
Stephan Morgenstern: Even the embedding process has become more demanding, starting with the coil. We have moved from small thread coils with a diameter of 12 centimeters to coils of about 25 centimeters and up to eight kilograms. To avoid overstretching the narrow security threads, they must be tension-controlled and unwound using a driven process. At the same time, threads are getting wider. We mainly use widths of three to five millimeters.
Does that make thread width the biggest hurdle in handling and processing?
Morgenstern: Yes, because the larger the water-impermeable surface – and that is what a foil is – the more difficult drainage becomes. In simple terms, we apply fibers at high dilution to a mesh and dewater until the initial sheet forms. During this sensitive phase, we introduce a relatively wide, thick “disruptive element” in the form of a plastic film.
Stephan Morgenstern, Head of Paper Production
The thread as the papermaker’s “enemy”?
Morgenstern: I would not call it an “enemy,” but in classic papermaking, everything that is not paper is seen as a nuisance. It can cause impurities and deposits in the paper machine, and in the worst case the threads stick to the drying cylinder. Our task today is the opposite: to unite two very different worlds and “marry” paper and film.
And this marriage calls for foil experts such as Patrick Engelmann?
Morgenstern: Ideally yes. No marriage works on its own, at least not in the long run (laughs).
Patrick Engelmann: A blank sheet is always easier to print than paper with four-millimeter-wide security threads. This is why the foil mill and the paper mill need to cooperate closely. Only then can new challenges, for example from stronger or more numerous visual effects, be tackled in a targeted way and driven forward efficiently.
»As the “depth of effects” increases, we also need a corresponding “depth of control”«
What new challenges do you see in thread production itself?
Engelmann: The complexity of optical effects, and therefore of the layer structure of a thread, is constantly increasing, while threads are also becoming wider. For the actual embedding and coating process, width and thickness are the decisive variables; everything else is primarily about appearance.
But the eye also “reads”.
Engelmann: Exactly. Modern security threads are designed to display optical effects. Both the human eye and our inspection systems play key roles here. Before a banknote owner can rely on what they see in everyday life, we must clearly evaluate whether the thread is embedded correctly, with the right window placement and the intended appearance.
Morgenstern: As the “depth of effects” increases, we also need a corresponding “depth of control.” Because production, development, and quality assurance are so close together, we can coordinate quickly even when requirements and complexities rise. That gives the product and the process a high level of security.
Patrick Engelmann, Project Manager Technologies, Threads & Foils
How does this “depth of security” show up in everyday circulation?
Engelmann: Authentication should work quickly with the human eye and be as independent of external conditions as possible. Whether in bright daylight or low light, the effects must clearly show: what I am holding in my hand is not a print or a copy, but a defined, hard-to-imitate feature. And this must still be true in a bar, in a restaurant, at sunset or in harsh sunlight, and even when the banknote is folded and creased. There are many counter examples that look impressive in a perfectly lit meeting room, but show very little under difficult lighting or after typical wear and tear.
Morgenstern: At the same time, the thread has to be firmly anchored in the paper. For me, security also means that the thread cannot simply be torn out, cut apart, and applied to a second note.
Engelmann: This is where the close interaction between paper and film comes into play again. On site we can quickly test and answer questions such as: What temperatures can the heat-sealing adhesive tolerate? How do we prevent the adhesive from clouding the effect or reacting with the film, while still providing the highest possible bond strength?
»As a system provider, we want and need to think beyond«
Are rising demands easier to meet when the paper and foil mills work as a “couple”?
Engelmann: Yes, because by working together we can not only use technologies faster, but also develop them further. Access to printing technologies that can mimic a banknote is easier than ever today, so as a system provider we have to think a step ahead. That also means our technologies must be suitable for qualification and industrialization for reliable large-scale use.
And ultimately fully integrated?
Engelmann: Exactly. We see the thread as an integral part of embedded security, attractively designed and equipped with appropriate machine readability. “Unmatched Security From Within” does not just mean that the thread is mechanically secure and cannot be detached from the paper. It also applies within the thread itself. For example, we can individualize the code embedded in the security thread using our MultiCode authentication technology, which makes it extremely difficult for counterfeiters to imitate the complex technology. Our registered thread embedding also plays a key role here: during paper production, the thread is registered so that the same effect is always visible in every window. This improves authentication and adds another level of security.
“Security by Complexity,” then?
Morgenstern: I would add “security by proximity.” Security needs proximity to reduce logistical friction. If both technologies are located at the same site, we can not only act and make decisions more quickly for each product, but also process, assess, and adapt the complete system.
Engelmann: That may sound theoretical, but in practice it means we are not 2,000 or 200 kilometers apart, but 200 meters. This has a direct impact on delivery times, coordination processes, and testing and inspection procedures. Our developers can stand next to the machines at short notice whenever needed.
»We supply complete turnkey products from a single source«
And your customers can experience their product directly on site?
Morgenstern: Yes, and this is something we consider a real strength. As a system supplier, we deliver complete turnkey products in which everything from thread development through embedding to advanced security features such as our MultiCode technology is coordinated and delivered from a single source.
Further Reading
RollingStar® i+ Security Thread
With RollingStar® i+ we have taken the visual impact and design possibilities for banknotes to a new level. Simple and fast authentication, outstanding visibility even in unfavourable lighting conditions and cutting-edge dynamics are among the highlights of RollingStar® i+.
Security by Design
Security technology and banknotes, that always means a forward-thinking and acting in advance – in the very best case in a tight interplay with banknote design. Learn more about the triad of design integration, inspiration, and identification.