The catchphrase “banknote security hangs by much more than a thread” is used by German printer Giesecke+Devrient’s Louisenthal paper-making subsidiary in pointing out that bank note security is not as simple as one may think.

The company mentions in its July newsletter that no one thing, such as a watermark, carries the full burden of security, but in a well-designed bank note, many features must come together in an optimal way.

It explains that security features need to work in a wide range of conditions, “not just in a laboratory, but in the evening in a restaurant, in a bar, at sunset, or in full sun.” Something can look great in a well-lit meeting room, but under less than ideal lighting conditions or when folded and creased, it becomes problematic. Also, security features need to be visible in a range of settings and on different denominations, while also contributing to the aesthetics of the note.

Part of the answer is in the work being done at Louisenthal to make security threads more appealing and more technically advanced. The width of the threads is increasing. Not only is this more attractive to the eye but the threads themselves can carry more security features.

One of them is called MultiCode, an exclusive magnetic coding authentication technology, in which the code embedded in a bank note’s security thread can be customized. Louisenthal calls its innovation “ingenious,” in that it enables the issuer to store information about the bank note denomination, its country and other specified information. It explains that details of how these codes are made are not publicly available and it is nearly impossible for counterfeiters to copy the technology. It is integrated during the thread production process and should last for the life of the note.

Incorporating a thread in a note is not as easy as it sounds, as shown by the first experiences with newest U.S. $100 Federal Reserve note. Louisenthal says, “Security threads also need to be firmly attached to the paper, and it should not be possible to tear them out. This is a challenge because the art of paper making is to create something as ‘pure’ as possible, but security threads mean introducing a deliberately disruptive element.”

Factors to be considered with new technologies, beyond printing, watermarks, and ink, include questions of what temperatures heat-sealing adhesive can tolerate, and how an adhesive can be prevented from tarnishing the note’s other effects.

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