The banknote: indomitable technologies
Counterfeiting banknotes is as old as banknotes themselves. Antique coins were even imitated at times and testing their authenticity was already a regular and almost mechanical requirement in daily transactions. Today, the manufacturing technology has evolved, but also that of counterfeiters. Central banks therefore call on manufacturers who themselves have a few tricks up their sleeve. This is an overview of a few different technologies present in the making of our banknotes.
Banknote manufacturers offer many means to guarantee authenticity of banknotes and fight against counterfeiting. Some authenticity markers are purposely visible so that users can quickly verify if bills they receive are genuine, others are kept secret precisely so that counterfeiters cannot reproduce them.
One of the most secure components in terms of preventing counterfeits remains the paper itself. Security paper is a paper that, along with other elements, will make it possible to certify a document or a banknote as authentic. Most banknotes are made from cotton paper, for added strength. Sometimes linen fibers or special colored fibers are mixed together to render counterfeiting more difficult. But some currencies are also made out of plastic (polymer) to improve their durability. Polymer has undeniable practical qualities, and Canada claims also to have a very secure bill with its $100 polymer note. Another way to secure the paper is for example the Basketweave technology, developed by the American company Simpson Security Papers, Inc. It includes a chemical safety that causes a combustion reaction or a visible stain when chemicals are applied to the paper. Invisible security fibers that will only be visible with ultraviolet light can also be integrated into the paper.
Security holograms are three-dimensional printed elements that are very complicated to reproduce due to their complexity and the cost of the technology required to manufacture them. This security feature is widely used and nearly 100 currencies use it in more than 300 different bills. These holograms can be incorporated in different ways, especially in windows of a few millimeters. The basic principle is the superposition of several printed layers, visible or not according to the angle and this process makes it impossible to scan, photograph or photocopy. Moreover, once embedded in paper, holograms cannot be removed without totally corrupting both the paper and the hologram itself. This technology, although relatively old and widespread, continues to evolve to constantly outrun potential counterfeiters and in march 2018, Louisenthal, a subsidiary of the German technology company Giesecke+Devrient Currency Technology, presented banknotes from all continents that are equipped with new types of color-changing holograms. The French Oberthur Fiduciaire has developed another way to integrate security features on banknotes at the time of printing with its Avalon technology. It is a fluorescent ink that has the peculiarity to change color temporarily if it gets rubbed.
Some banknotes also incorporate sheets or wires which hold different technological tools such as iridescent characteristics or various optical effects and are threaded through the paper. There are two types of security threads: a thin polyester film covered with aluminum, partially demetallized and embedded in the paper or covering it; or a sewing thread made of fluorescent synthetic fibers, but this one is reserved for passport binding. Often the ribbon extends vertically and contains text or numbers. Crane Currency, for example, a company owned by Crane Co. Company, has developed the Motion security thread. It is both visible to users for quick verification and very difficult for counterfeiters to reproduce. Similar technology is also integrated into the banknotes manufactured by De La Rue. Indeed, the British company also offers different kinds of color changing security threads such as Active or Kinetic StarChrome, which have aesthetic as well as safety virtues.
The watermark technology is certainly the most widely known technology among the general public and the user's reflex is indeed to lift the banknotes in front of a light source to see the invisible image appear. Introduced in the 13th century, this technology requires adding a metal stamp on the paper at the time of printing. The Dutch high-end security paper company VHP, for instance, offers two kinds of watermarks that are easily recognizable by the public: the Pixel, which has the particularity of being multi-tone, and HD Vision, a technology that has placed more emphasis on detail and definition.
Quantity and diversity
The technological tools which ensure the authenticity of banknotes and which prevent their illicit reproduction are plentiful and constantly evolving. Several dozen security features can be found on a single banknote and these are all possibilities central banks can use to secure their currencies. In a technological race against counterfeiting, the safest solution is and will remain the variety and number of technologies employed by central banks. Several are needed to make the work of counterfeiters too difficlut and/or non-profitable. In short, none of these technologies is indispensable and sufficient by itself, it is the number and accumulation of these tools that make the banknotes almost impossible to counterfeit. Attached files: