Felix Ehrtmann, Product Manager Integration + Print at G+D Currency Technology

When you pull a banknote from your wallet, you usually don’t begin by hunting for a watermark you rather feel it first: the snap of the paper, the tactile structure of the print, the overall “signature” of a high-security substrate. This creates an initial authenticity check before any conscious verification begins. Or, as Felix Ehrtmann, puts it: “Trust is the foundation of every currency. And it’s something that doesn’t just happen; it’s built through thoughtful design, technology, and communication.”

A “desktop threat” that changes the rules

Today, however counterfeiting is no longer defined only by specialists with rare equipment; increasingly, the pressure comes from accessible reproduction technologies that are easy to obtain and relatively cheap. “We are seeing more use of advanced inkjet and toner-based systems that are widely available,” says Ehrtmann. “These technologies may replicate the look of some features, but not the substance behind them.” 

That shift makes a crucial point for central banks: security cannot be treated as a set of isolated effects. A holographic element here or a printed feature there is not enough on its own. Resilience comes from a systems approach, substrate and print working together, so that imitation requires more than copying surface appearance. 

Integrated substrate features

In practice, that system is built as a layered workload: 

  • Integrated substrate features (such as multitonal watermarks and dynamic security threads such as RollingStar®) that cannot be reproduced with common print technology.
  • Printed and applied tactile and optical effects (for example, intaglio structures and dynamic inks and security foils such as RollingStar® Patch) that add complexity and enable fast public checking.
  • Machine-readable elements that support authentication across the cash cycle, from vending and ticket machines to high-speed processing.
  • Central-bank-specific features such as the M-Feature® that function as an effective ultimate barrier. 

 

Balance is the thread that connects these layers. In a well-designed banknote, security does not sit only on the surface, and it does not rely on one “hero feature.” Instead, substrate and print reinforce each other. “Typically, around half of the protection comes from features integrated into the paper itself - such as watermarks, threads, and security fibers - and the other half comes from printing and applied elements,” Ehrtmann explains. Together, they form a lock-and-key relationship: embedded features provide depth and integrity; print provides fast recognition, tactile verification, and additional optical complexity.

Banknote substrate and print reinforce each other

Embedded vs applied security: why the substrate choice matters

Seen through the lens of resilience, the strategic question is where security “lives”: inside the substrate, or mainly on the surface? In natural fiber-based notes, core features are integrated into the body of the banknote. “Watermarks and threads are part of the substrate, fully integrated within the fibers ,” says Ehrtmann. “That makes a fundamental difference, because embedded security cannot be reproduced in the same way as surface applied features.”

By contrast, polymer notes rely almost only their protection toward what can be applied to the surface. “Even today, a large share of the protection in polymer comes from printing on the surface,” Ehrtmann notes. For central banks, the practical implication is not a simple material preference, but a question of design latitude: how many security layers can be built into the substrate itself, and how much depends on surface-applied effects. 

He also draws a line between visual novelty and security depth: “A clear window is often presented as a security element,” he says. “But strategically, it’s important to ask what it really is: a cutout of ink.” The question is not whether a feature looks distinctive, but whether it contributes meaningfully to a layered system that is hard to imitate with accessible reproduction methods. 

Security built from the inside out

The most effective banknote security is often the security people can verify naturally. This is where tactility becomes more than a “nice-to-have.” Raised printing and clear structures support fast, confident authentication in everyday use and they are difficult to imitate convincingly without industrial-grade equipment. 

So as reproduction technology becomes more accessible, the strategic advantage shifts toward banknotes that are secure not only in theory, but in practice: layered, intuitive to check, and resilient in the hands of the public. In the end, the choice is not simply one feature versus another, or one material versus another. It is a decision about whether security should live mainly on the surface or be built from the inside out.