Glossary

The illegal transportation of objects, substances, information or people across an international border, in violation of applicable laws or other regulations, often to avoid taxation.

A banknote that has become dirty through usage, usually from greasy materials sticking to the surface or from the absorption and adhesion of dust and particles to the cotton fibres of the note. Soiling is one of the main reasons for banknote deterioration and subsequent destruction.

The process of fitness sorting of banknotes by their condition of use. Through this process, used banknotes are classified as fit or unfit to return into circulation.

An advanced Raman spectroscopy technique used to analyse chemical compositions beneath the surface of a sample without needing to physically cut or otherwise disturb it. In traditional Raman spectroscopy, the laser light and detector are aligned directly on the sample surface, which only provides surface-level information. SORS, however, works by offsetting the detector to capture Raman signals from deeper within the sample.

A sample banknote with no value that is legitimate and numbered, and marked by printing ink or perforation system with the word ‘specimen’. Specimens are exchanged among monetary authorities and in the past sent also to correspondent banks to share information on a new banknote or new series.

Produced by the mutual interference of a set of coherent wavefronts. Speckle patterns have been used in a variety of applications in microscopy, imaging, optical manipulation and document biometrics (or fingerprinting). They typically occur in diffuse reflections of monochromatic light such as laser light.

The study of the absorption and emission of light and other radiation by matter. Involves the splitting of light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), which is done in much the same way as a prism splitting light into a rainbow of colours. More recently, the definition has been expanded to include the study of interactions between particles such as electrons, protons, and ions, as well as their interaction with other particles as a function of their collision energy.

A process employed in offset printing where colours are intentionally allowed to overlap on the transfer cylinder producing a gradated effect.

Any colour printed with its own ink, in contrast to process colour printing which uses four inks (cyan, magenta, yellow and black – or CMYK) to produce all other colours.

The practice of representing information within another message or physical object so that its presence is not evident in human inspection. The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny

The suspension of fibre and other materials in water used to manufacture paper.

One of the functions of money or more generally of any asset that can be saved and exchanged at a later time without loss of its purchasing power. See also Precautionary holding.

A simple paper device designed to hold a specific denomination and number of banknotes. Can also refer to a bundle of banknotes.

The process of stamping a coin blank with a design. The stamping speed is measured in the number of strikes per minute.

The material or base – eg. paper or film – on which an image is printed or a feature applied.

A mobile or web application that can provide multiple services including payment and financial transaction processing, effectively becoming an all-encompassing self-contained commerce and communication online platform that embraces many aspects of personal and commercial life.

Security features that are applied to the surface of a banknote or secure document (eg. foil stripes, foil or optically variable ink patches, iridescent coatings) as opposed to features that are created through combinations of printing techniques or features integrated into the substrate, such as threads, fibres and watermarks.

The most ubiquitous and popular type of hologram, mainly exhibiting a characteristic rainbow-coloured pattern. The details of the hologram image are recorded as an interference pattern on the surface (rather than through the volume) of the material. The value of surface relief holograms is that they can be mass-produced mechanically by embossing or casting a relief pattern or image into an inexpensive thermoplastic film or viscous coating on a film or paper.

The property of a banknote or secure document feature that can be felt, often made by means of intaglio printing.

Marks printed in intaglio, recognisable by feel and usually located close to the edge of a banknote.

Molecular or microscopic particle that can be organic or inorganic in composition and exhibit specific and unique physical, biological, chemical or spectroscopic properties. Added in very low concentration to substrates or ink as a covert authentication feature.

An ink that undergoes a reversible colour shift when heated and then cooled. The temperature change can be quite narrow so the viewer’s external body temperature, by applying, say, a thumb to the printed surface, is sufficient to trigger the transition.

A method of coating a very thin film of material – between a few nanometers to about 100 micrometres’ thickness – onto a substrate surface, or onto a previously deposited coating to form layers.

The superposition of two or more lightwaves, causing their mutual amplification or reduction depending on how the phases of these waves are related to each other.

The amount by which a measurement or calculation might change and still be acceptable.

The passing of light through an object (as opposed to light reflecting off or absorbed by an object). Watermarks in security paper are usually viewed in transmitted light by holding the paper up to the light source.

A transparent area on a banknote incorporating optical effects by applying different elements, such as inkless embossing, liquid crystals or an optically variable device. Currently used both on polymer and paper banknotes.

Anglo-Saxon weight unit, equivalent to 31.10 grammes. Used in the precious metals industry.

A photochemical process in which high-intensity ultraviolet light is used to instantly cure or ‘dry’ inks, coatings or adhesives.

A first-level requirement of security paper, which needs to be made from virgin pulp without optical brighteners (ie. which is UV-dull). This is because optical brighteners mask or interfere with UV fluorescent security print and fibres.

Electromagnetic waves located beyond the blue end of the visible light spectrum, commonly defined within the wavelength range of 100nm-400nm. UV light is often used to analyse secure documents and banknotes, and security features such as paper brightness, fluorescent inks and fluorescent fibres. UV lamps used in shops and banks to verify banknotes operate at a wavelength of 365nm.

People who do not have a bank account.

A coin which has not been distributed or used as currency.

People who have a bank account but do not actively use it. For example, they may receive a government benefit payment into the account but they then withdraw it in cash and do not use the account further.

The opposite of a fit banknote. A banknote which, due to its deterioration or poor quality, is no longer suitable to be returned into circulation, and will be destroyed by the central bank.

A coin, banknote, medal or token which has only been struck on one side.

A material that absorbs energy at a longer wavelength outside the visible spectrum and emits in the visible spectrum. The materials that can achieve this effect are rare and therefore used for security marking.

A process for creating a layer of metal on a substrate. Involves heating the metal target material until it vapourises inside a vacuum chamber. This allows the metal vapour to condensate and form a thin layer over the top of the substrate. Vacuum deposition is a common method of producing security threads.

The use of digital print processes to apply personalised and serialised information, such as unique identifiers and barcodes, to products and documents.

Applied to a banknote, this is the process by which the surface of the note is coated with a layer of varnish with the purpose of decreasing the level of absorption of the substrate, thereby reducing its soiling and prolonging the life of the note in circulation.

Unlike raster images, a vector is not composed of separate dots (pixels). Vector graphics are composed of control points with curves in between them, defined by a mathematical formula. Vector graphics are often used for printing brochures etc., which do not require accurate transmission of all the shades of a particular colour and which can be described by curves. A great advantage of vector graphics is that the scaling of images does not affect their quality. One of the most popular vector graphics editors is Adobe Illustrator.

The process of verifying specific identity, document or product attributes, or determining the authenticity of credentials in order to give authorisation for a particular service.

A small illustration on a banknote that fades into the background rather than being framed by a border.

The reformation of cellulose to give a textile fibre that may carry security features and be embedded into security paper.

The fraudulent practice of making phone calls or leaving voice messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as bank details and credit card numbers.

Wavelengths within the visible spectrum of 380nm-740nm.

A method of making copy-evident and tamper-resistant patterns in the background of a document. Normally these are invisible to the naked eye, but become obvious when the document is photocopied. Typically, they spell out ‘void’, ‘copy’, or ‘invalid’. See also Big dot little dot.

Refers to holograms where the thickness of the recording material is much larger than the wavelength of light used for recording. One of the most common types of hologram (together with surface relief holograms), volume holograms are mass-produced through optical copying of a master hologram onto photopolymer materials, so they retain more of the optical properties of the master than the mechanical, surface relief process. This allows them to be used for classical holograms which are fully 3D images, displaying depth and both vertical and horizontal parallax. Volume holograms are either monochromatic or two-colour, with a distinctly different appearance to rainbow holograms, which are based on diffraction.

A means of defacing coins to render them worthless/unfit for circulation prior to being melted down or sold for scrap. The process takes its name from the pattern forced into the surface of coins under extreme pressure, which distorts it by creating a series of wavy lines similar to a waffle.

An image in paper produced by varying the thickness and density of the paper mass during paper production. These variations form a discernible image that can be viewed when holding the paper up to the light. Used as a security feature on most banknotes.