The Bank of England has issued banknotes since it was founded in 1694 and today all Bank of England notes are produced by De La Rue Currency, a subsiduary of De La Rue plc, situated at Loughton in Essex.
One of the aims at every stage is to ensure that the note is as difficult as possible to counterfeit. Some images are engraved by hand into metal plates, whilst others are created using a Computer Aided Design (CAD) system and are drawn onto film by a laserbeam. When finished, the images are duplicated many times onto printed plates ready for the presses. Specialised inks used to produce the notes are also manufactured on site; approximately 85 are required for the four denominations.
The paper for Bank of England notes is made by a specialist paper manufacturer. It is manufactured from cotton fibre and linen rag, which makes it tougher and more durable than the more common wood pulp paper. Using copious amounts of water, the cotton is broken down into individual fibres and reformed into reels of paper of the quality required.
The watermark design is engraved in wax and, like the metallic thread, the image is incorporated into the paper at the manufacturing stage.
The banknote printing process
Currently three printing processes are used in the printing of banknotes.
• Offset Litho
Offset Litho – the printing plates transfer the ink to the paper via an intermediate offset roller. This process is used to print most of the front and back of the note except for the portrait of Her Majesty the Queen, the lettering and the numbering. Offset printing involves a number of separate plates with different colours superimposed in close register to produce high quality clearly defined images.
Intaglio – this process is used to add the portrait of Her Majesty the Queen and the raised print on the front of the note. The ink rests in grooves engraved in the printing plate. When the plate comes into contact with the paper the ink is forcibly ‘drawn’ from the plate onto the paper under very high pressure. This produces the raised print which is one of the characteristics that gives Bank of England notes their distinctive feel.
Letterpress – this process is used for the cypher and serial numbers on the front of the note. Ink is transferred onto raised letters and digits which are then printed onto the note.