Most banknotes are made of dense 80 to 90 grams per square meter cotton paper (see also paper), sometimes mixed with linen, abaca, or other textile fibres. Generally, the paper used is different from ordinary paper: it is much more resilient, resists wear and tear, and also does not contain the usual agents that make ordinary paper glow slightly under ultraviolet light.
Early Chinese banknotes were printed on paper made of mulberry bark and this fibre is used in Japanese banknote paper today.
Unlike most printing and writing paper, banknote paper is impregnated with polyvinyl alcohol or gelatin to give it extra strength.
Most banknotes are made using the mould made process in which a watermark and thread is incorporated during the paper forming process.
The thread is a simple looking security component found in most banknotes. It is however often rather complex in construction comprising fluorescent, magnetic, metallic and micro print elements. By combining it with watermarking technology the thread can be made to surface periodically on one side only. This is known as windowed thread and further increases the counterfeit resistance of the banknote paper. This process was invented by Portals, part of the De La Rue group in the UK.
Recently this company has introduced many new features to the banknote world including Cornerstone, Platinum and Optiks, all registered trade marks of De La Rue. Cornerstone uses watermarking to reduce the number of corner folds by strengthening this part of the note. Platinum is a special coating to reduce the dirt picked up by banknotes. Optiks is a new thread based security feature that creates a plastic window in the paper which is very hard to copy.
Durable banknote papers
Banknote paper with enhanced durability is a recent development, designed to meet the growing need for popular low-denomination banknotes to withstand extreme wear.
Improved protection against dirt: Manufacturers of banknote paper were quick to recognize the problems associated with dirt and developed a special paper with a thin layer of varnish on the surface to repel soiling. This layer is applied directly to the substrate. The thickness and structure of the paper remain unchanged, thereby preserving the natural feel. The so-called Durable Banknote Papers, which are available in the global banknote market under brand names, such as LongLife, Platinum, Marathon Coated, Diamone, and Flesure, protect banknotes from soiling and environmental incluences, making it possible for them to remain in circulation for longer.
Increased mechanical stability: With new products, such as Synthec and Diamone Composite, banknote manufacturers have gone a step further and responded to the growing demand for higher mechanical stability of the paper—because the longer a banknote stays in circulation, the limper it becomes and the more easily it tears. Synthec substrate, for example, consists of 80 percent cotton fiber and 20 percent synthetic fiber, with the latter being longer and more flexible than the former. The synthetic fibers constitute a dense network within the cotton fiber structure, supporting the banknote like a kind of corset and increasing its mechanical stability. This practically doubles the useful life of the product. Synthec is much less sensitive to climate fluctuations than standard banknote paper. The synthetic fibers are incorporated in the banknote substrate at the sheet formation stage. This has the advantage that all established security features—such as three dimensional watermarks, fluorescent fibers, security threads, or the innovative new varifeye®Synthec substrate, just as they would be with the standard cotton substrate. Optically variable effect inks and foil elements, such as holograms, can be applied to this substrate in the same way as with traditional banknote paper. Public confidence in the established security features, built up over decades, remains intact. To ensure that the banknotes are also protected against dirt, they are given a standard coating of varnish. By the end of 2007, Synthec banknotes will be circulating in three countries, including an African country with different climate zones that has chosen Synthec as a substrate for its lowest-denomination note. In the south of the country conditions are tropical, with a rainy season that lasts for eight months, while the north is very arid and extremely hot, with temperatures reaching 41 degrees Celsius. see-through window—can be integrated into the new
Counterfeiting and security measures on paper banknotes
The first kinegram banknote, the 1988 Austrian 5000 Schilling note (Mozart)
The ease with which paper money can be created, by both legitimate authorities and counterfeiters, has led both to a temptation in times of crisis such as war or revolution to produce paper money which was not supported by precious metal or other goods, thus leading to hyperinflation and a loss of faith in the value of paper money, e.g. the Continental Currency produced by the Continental Congress during the American Revolution, the Assignats produced during the French Revolution, the paper currency produced by the Confederate States of America and the Individual States of the Confederate States of America, the financing of the First World War by the Central Powers (by 1922 1 gold Austro-Hungarian krone of 1914 was worth 14,400 paper Kronen), the devaluation of the Yugoslav Dinar in the 1990s, etc. Banknotes may also be overprinted to reflect political changes that occur faster than new currency can be printed.
In 1988, Austria produced the 5000 Schilling banknote (Mozart), which is the first foil application (Kinegram) to a paper banknote in the history of banknote printing. The application of optical features is now in common use throughout the world.
Many countries' banknotes now have embedded holograms.
The first Australian polymer banknote, the 1988 $10 commemorative issue
In 1983, Costa Rica and Haiti issued the first Tyvek and the Isle of Man issued the first Bradvek polymer (or plastic) banknotes; these were printed by the American Banknote Company and developed by DuPont. In 1988, after significant research and development by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Reserve Bank of Australia, Australia produced the first polymer banknote made from biaxially-oriented polypropylene (plastic), and in 1996 became the first country to have a full set of circulating polymer banknotes of all denominations. Since then, other countries to adopt circulating polymer banknotes include Bangladesh, Brazil, Brunei, Chile, Indonesia, Malaysia, Mexico, Nepal, New Zealand, Papua and New Guinea, Romania, Singapore, the Solomon Islands, Sri Lanka, Thailand, Viet Nam, Western Samoa and Zambia, with other countries issuing commemorative polymer notes, including China, Kuwait, the Northern Bank of Northern Ireland, Taiwan. Other countries indicating plans to issue polymer banknotes include Nigeria. In 2005, Bulgaria issued the world's first hybrid paper-polymer banknote.
Polymer banknotes were developed to improve durability and prevent counterfeiting through incorporated security features, such as optically variable devices that are extremely difficult to reproduce.
The uptake of polymer banknotes has however been comparatively slow with an estimated 1.5% of the Worlds banknotes now using this material. Problems with print durability and the very bulky nature of creased polymer notes rank high amongst the problems limiting polymer uptake. Some countries such as Sri Lanka and Thailand have reverted to paper after testing polymer notes in circulation.
Over the years, a number of materials other than paper have been used to print banknotes. This includes various textiles, including silk, and materials such as leather.
Silk and other fibers have been commonly used in the manufacture of various banknote papers, intended to provide both additional durability and security. Crane and Company patented banknote paper with embedded silk threads in 1844 and has supplied paper to the United States Treasury since 1879. Banknotes printed on pure silk "paper" include "emergency money" (Notgeld) issues from a number of German towns in 1923 during a period of fiscal crisis and hyperinflation. Most notoriously, Bielefeld produced a number of silk, leather, velvet, linen and wood issues, and although these issues were produced primarily for collectors, rather than for circulation, they are in demand by collectors. Banknotes printed on cloth include a number of Communist Revolutionary issues in China from areas such as Xinjiang, or Sinkiang, in the United Islamic Republic of East Turkestan in 1933. Emergency money was also printed in 1902 on khaki shirt fabric during the Boer War.
Leather banknotes (or coins) were issued in a number of sieges, as well as in other times of emergency. During the Russian administration of Alaska, banknotes were printed on sealskin. A number of 19th century issues are known in Germanic and Baltic states, including the towns of Dorpat, Pernau, Reval, Werro and Woisek. In addition to the Bielefeld issues, other German leather Notgeld from 1923 is known from Borna, Osterwieck, Paderborn and Pößneck.
Other issues from 1923 were printed on wood, which was also used in Canada in 1763-1764 during Pontiac's War, and by the Hudson's Bay Company. In 1848, in Bohemia, wooden checkerboard pieces were used as money.
Even playing cards were used for currency in France in the early 19th Century, and in French Canada from 1685 until 1757, in the Isle of Man in the beginning of the 19th Century, and again in Germany after World War I.