Producing a coin - The mint's role

The Mint makes a robust version of the plaster model by taking a mould, then using electroplating techniques to make an ‘electroform’ or ‘electrotype’ copy. This is capable of withstanding the physical process of reduction to coin size.

Today the reduction process is based on a digital scan which is sent to a computer-controlled engraving machine. Until recently this was a mechanical process, in which a physical tracer was run over the design and its movements were replicated mechanically at a smaller scale on machines such as the ‘Janvier’ (pictured).

Both methods create a miniature copy in steel, known as a ‘reduction punch’. It is hardened so that it is tough enough to punch the image into a metal blank, known as a ‘reduction die’. The die is then hardened as well, so it is tough enough to strike many thousands of times. A die is made for both sides of the coin.

The Mint prepares blank coin disks in advance. They are made from a metal alloy which is melted, cooled, and rolled out to coin thickness. Blank disks are punched out at the correct size, then softened, cleaned and dried.

The dies and the blank coins are brought together in coining presses. Blank coins are automatically fed between the two dies, and struck at speeds of up to 750 per minute.

The coins are not legal tender until they are validated by the relevant authority. In the UK this takes the form of a Royal Proclamation issued through the Privy Council.