( Written by : N.R. Jayaraman)
Bank Notes issued by several countries contain many security features, few important amongst them being Security thread and OVD features. In order to enhance the security of the bank notes, these features are developed to impede forgery and counterfeiting. It is not possible to eliminate counterfeiting fully, whatever be the best feature solution deployed. However since the counterfeiters are able to find some way or the other to forge the notes, the Bank Note issuing authorities try to go in for technology that makes it highly difficult to counterfeit the notes so easily due to the high cost and intricate technology involved.
Acknowledgement: This article discussing one such security feature has been compiled with major and main inputs from - All that Glitters ... written in the year 2001 by Mr. Peter Symes (p j symes) who is expert author on world paper money. Researching various aspects of world paper money, Mr. Peter Symes has published the results and his findings in books and articles. Many of his articles have been published in the International Bank Note Society Journal. Most of the contents of this article is mainly from that of Mr. Peter Symes, but presented in different format adding subsequent developments around the world. This has been written with the sole aim of enhancing the knowledge of the students in printing and those working in the Security Printing Presses.
I sincerely thank Mr. Peter Symes who has given me special permission to use the inputs from his articles and to reproduce them in this blogger for the benefit of the printers and students - N.R. Jayaraman
Glitter on Bank Notes and World Currencies
The Bank Notes issued by the Bank Note and Currency issuing authorities contain certain features such as Guilloche design, Security thread, micro letters, see through design, embedded Water mark, Latent images etc common to all. But quite a few countries opt for additional features such as OVD, OVI, Color shift thread, Fluoresce thread, Micro lettered thread, hidden colored fibers that glow on paper surface under UV light, Holograms, Taggants that can be only detected with a special apparatus, and special inks such as Intaglio inks, Fluorescent and phosphorescent inks, Infrared up-converting inks, Thermochromic inks, Machine-readable inks etc which were developed in the recent past.
A close look at many of the bank notes issued throughout the world today will show that quite a few of them in one way or the other carry security features that glitter, shine, sparkle and change color as the angle of view or the angle of illumination changes. These features have became more common on banknotes.
The first of the security feature that was incorporated into a banknote that had reflective properties was the ‘Stardust’ security thread, which is also known as the ‘segmented thread’ or the ‘windowed thread’ which was embedded into the paper as if they have been woven on the paper. The surface of the embedded thread is coated with aluminum but has dull shine.
With the passage of years the Stardust thread became a common security feature on many banknotes . Examples of the wide and a narrow Stardust thread can be seen on the '1000-new-zaires note' (Two threads in one single note) of the country Zaire (African Country), issued in the year 1995.
While Stardust threads have a shiny surface, this quality was not the driving force behind their introduction. The shine or ‘glitter’ was largely a by-product of the innovation. Once the Stardust threads were introduced slowly the qualities of ‘glitter’ were increased by coating with an iridescence surface. The exposed surface of some of these security threads reflected the colors of the spectrum when ordinary light hit the surface. Initially when this was introduced they were expected to be extensively used by many countries in their bank notes. Two series of denominations -'100 and 500-taka notes' issued by Bangladesh issued in the year 2000 and 2001 carried security threads with this feature. The Stardust feature was also used in some of the Currencies issued by England, as well as some of the new issues from Germany, Zambia and Nigeria. Some of the notes of Bolivia had threads which glow under ultraviolet light, and the commemorative 60 baht note from Thailand had a micro printed, colored, broken thread where the blue sections glow when placed under ultraviolet light.
advancement to the technology the ‘glitter’ content of the threads on
the banknotes were increased by way of introducing foil strip,
which contained silver foil and transparent tape as alternate sections,
the silver portions cut at an angle (something like Windowed security
Examples of this type of foil strip are found on '5,000- and 10,000-franc notes' issued by the Central Bank of the West African States. A variation of this strip appears on the '10,000-franc note' issued by the Central Bank of the Comores (The Comoros, officially the Union of the Comoros is a sovereign archipelago island nation in the Indian Ocean, located at the northern end of the Mozambique Channel off the eastern coast of Africa), where the foil strip was wider and the reflective sections were gold but not that of silver (Issue year not available). These adhesive strips, with metallic and clear sections, are one of the French security printer’s contribution to the world of glitter.
Other security printers in order to add glitter to their notes used simple silver foil stamps. The foil stamps were cut into specific shapes and affixed to the banknote (all by automated paper making machines and not a manual process). An example of this can be seen on the '500-dirham note' issued by the United Arab Emirates. Initially issued in 1993 without the foil stamp, the new security feature was added to the issue dated 1996. The foil stamp image on this issue is the silhouette of a fortified tower.
Foil stamps containing images that reflect light increased the ‘glitter’ feature. Generically known as Optically Variable Devices (OVDs) examples of foil stamps with reflected images are now found on many banknotes, although the style of these devices differ.
One of the first OVD features was used in the year 1988 on the '10-dollar commemorative note' issued in Australia. The iridescent foil stamp used on these notes was suspended in a clear window and had a portrait of Captain Cook that reflected the colors of the spectrum as the angle of light changes. This style of OVD had been used on a number of notes designed by Note Printing of Australia that included Indonesia's '50,000-rupiah note', issued in 1993 and the '50-dollar commemorative note' issued by Singapore in the year 1990. A different style of foil stamp produced by Note Printing of Australia can be found on the '100-yuan polymer note' issued in China in the year 2000. In this case the foil stamp is not suspended in the clear window of the note, but is affixed to the polymer surface. The foil stamp had an image incised in the foil, causing light to be reflected in an iridescent pattern.
The OVDs used by Note Printing of Australia contain single image that reflect the colors of the spectrum as the angle of the light changes. Images on different other type of OVDs caused the images to appear and disappear as the angle of the light changed. Such features were used on the higher denomination notes issued in Kuwait. Cut in the shape of an bird’s head, the foil stamp on the notes contained multiple images of a sailing vessel and numerals of the denomination in Arabic language, which appeared and disappeared as the foil stamp was tilted at different angles.
A similar feature appeared on the notes issued by the Chatham Islands (The Chatham Islands is an archipelago in the Pacific Ocean about 680 kilometers southeast of New Zealand. It consists of about ten islands within a 40-kilometre radius, the largest of which are Chatham Island and Pitt Island) to celebrate its status as the first place to see the sun in the new millennium. On these notes a foil circle contains repetitions of ‘2000’ that appear and disappear as the note is held at different angles. The various repetitions also change color as light is reflected.
The largest OVDs with iridescent images used on the bank notes were that of Saudi Arabia which can be seen on the '20- and 200-riyal notes' issued by the Kingdom of Saudi Arabia to celebrate its centenary. The OVD was constructed in two parts, a central section and a border section. The border contained many small representations of the Saudi symbol of a palm tree surmounting two crossed swords. In the center of the OVD on the Saudi Arabian notes two discrete images could be seen -one a circular pattern containing Arabic text and the other a symbol that expressed the centenary of the Kingdom of Saudi Arabia.
Following the production of images on foil stamps, foil strips were manufactured with the same properties and those strips made an impact on the ‘glitter’ market. Combining reflective images with the benefits of affixing continuous foil strips to sheet of banknotes, many issuing authorities are making increased use of the glitter properties provided by such devices. This type of foil strips can be seen on notes issued by Eritrea, Oman, Yemen and the United Arab Emirates. In each case an iridescent pattern is repeated on the strip and in some cases the denomination is etched into the strip by a separate process.
The glittering foils are in no way comparable to holograms even though some foils have holographic images embedded in them. A true hologram has an image with depth and none of the foil stamps described so far have images with this property. Examples of holographic foils are found on a '500-riyal note' issued in Qatar and in the higher denomination notes of Bahrain. A holographic metallic strip with vertically and horizontally repeated inscription 500 LTL can be seen on the 500 litas banknote issued by LIETUVOS BANKAS in the year 2000.
The '500-riyal note' issued by the Qatar Central Bank in 1996 contains a foil stamp with a hologram consisting of the state emblem surmounted by the denomination in Arabic numerals. Surrounding this image is the denomination repeated many times in iridescent Arabic and western numerals. The denomination in Arabic numerals is apparent when the note is tilted at one angle, but they disappear and the denomination in western numerals appears when the angle of light changes. Most importantly, while most iterations of the denomination appear to be placed on the surface of the foil stamp, three rows of the denomination seem to be running beneath the state emblem at a level below the surface of the hologram. This appearance of depth occurs only on a hologram.
Similar characteristics are apparent in the holograms used on the high denomination notes issued by Bahrain in 1998. In this case the principal images are the head of an Oryx ( an animal similar to buffalo) and the denomination in Arabic numerals. Once again, repetitions of the denomination, in iridescent Arabic and western numerals, appear to be displayed at different depths within the hologram. Holograms and kinegrams are reported to be the most advanced security features of today. Holograms usually show a volumetric image, while kinegram changes colors when a viewpoint is changed. Impossible to be reproduced without extremely expensive equipment, they gain more and more popularity. As usual, the kinegrams incorporate the denomination of the banknote - to avoid all possible disputes and questions, while holograms depict portraits. On the left is the kinegram image from the 50 euro banknote.
Since the use of reflective foil feature is relatively expensive they are only used on high denomination notes. Shortly after Australia introduced the OVD in the bicentennial 10-dollar note, the United States of America’s Bureau of Printing and Engraving tested the OVD with adverse results. In one of the tests called crush test, the banknote taken up for testing is rolled tightly to the size of a cigarette and placed into a cylinder and crushed. When subjected to this test the OVD shattered and it was therefore deemed an unacceptable technology to adopt.
Technology has moved in many directions since 1988 when the OVD was first introduced, but there are still many authorities who have not adopted this technology. Some may not do so in the belief that the feature will fail to sustain the wear that circulation demands and some may not use the technology because of the cost.
Most of the Bank Notes issued by different Countries contain another glitter feature called OVI meaning Optically Variable feature. This is done using special inks that change their color when viewed from different angles. The composition of the inks are such that they change colors when viewed from angles. In this direction of glitter Luminescent ink have been used on the 10000 yen notes issued by Japan. The improved modern version of Windowed security threads has color changing feature and are comparable to highly advanced holographic feature and are in use on many of the Bank Notes issued by the authorities.