From cotton fields to paper mills

Perhaps symbolic of the euro's status as a major international currency, the raw material for the banknotes comes from different regions of the world. Cotton grown in the American South, in Africa or on the steppes of Central Asia is the basic ingredient in euro banknote "paper", which is in fact made from pure cotton fibres. The fibres cannot be used by the textile industry, as they are too short for weaving, so they are bought by paper mills, which turn them into cotton paper.

This is what gives euro banknotes their special "feel" and crispness, as well as durability. They are more robust and better withstand a certain amount of rough treatment than most other types of paper. The cotton fibres are bleached in water at high pressure and high temperature. The paper pulp is then fed into a paper machine. Security paper forms the substrate or basis for producing banknotes, and certain security features, such as watermarks or embedded threads, are integrated into the paper itself. The watermark, for example, is obtained by varying the paper thickness during the paper-making process; some parts become more transparent or lighter than the surrounding paper, while other parts become darker.

Turning banknote paper into banknotes

Banknote paper is distributed to the 14 high-security printing works in Europe that produce euro banknotes. There are two main processes: offset and intaglio printing. Different types of plates and special inks have to be used for these processes. Each plate is generally used to print over half a million sheets, and these, in turn, are cut into around 25 million banknotes. Approximately 40,000 sheets can be produced in an eight-hour shift, i.e. around 2 million banknotes. Both sides of a banknote can be printed simultaneously using offset printing machines.

Offset Printing

This process involves printing the offset designs on the front and back of the banknotes simultaneously. The printing plates transfer the ink to the paper via an intitleediate offset cylinder. Offset printing involves a number of separate plates with different colours superimposed in close register to produce high-quality, clearly defined images. The background images on the front and all images on the back of the banknotes are printed in offset.

Intaglio Printing

With intaglio printing, the ink is poured into grooves engraved on the plate. When the plate comes into contact with the paper, the ink is forcibly transferred onto the paper to produce raised print. Intaglio elements are printed on the front of the banknotes. Only raised print can only be found on the front, eg in the window or doorway. Intaglio printing contributes to the special "feel" of euro banknotes: users can check they are genuine by running their fingers across the large numerals or the windows and doorways on the front. In order to print in relief, intaglio plates with special inks are applied to the paper with a force of some 30 tonnes. In addition to these traditional banknote printing techniques, a hot stamping process is used to apply a hologram foil. A colour-changing number on the back of the higher-value denominations is applied by silk screen printing. Each banknote receives a unique serial number consisting of one letter and 11 digits. Many additional features are included to help the public, as well as professional cash handlers and central banks, to detitleine if a banknote is genuine or counterfeit.

Silk-screen Printing

On a silk-screen printing machine, the ink is passed through the open sections of a stencil. The glossy stripe and the colour-changing number are printed this way.

Foil Application

The hologram stripe or patch is hot-stamped onto the banknote paper.

Letterpress Printing

The banknote serial numbers are printed with the aid of numbering boxes.

Extensive testing prior to circulation

Occasional flaws are bound to occur in any mass production process. To ensure the consistent quality of euro banknotes, the ECB has devised a common quality management system for all the banknote printing works. Throughout the production process, hundreds of manual and automated tests are performed to ensure that the banknotes meet the ECB's standards. For example, the banknotes are subjected to tearing, soiling and even washing machine tests to measure their resistance.

Once the quality specifications have been met and the banknote sheets cut up, the individual banknotes are packaged per denomination and stored in secure areas at the printing works prior to distribution. They are first taken from the printing works to the national central banks, which place them in their vaults.