In a month where the UK Prime Minister has formally begun so called Brexit proceedings, it is almost amusing that the Royal Mint has also released a new two-tone pound coin that looks more than a little like the One Euro coin.
However, the two coloured metals are where the similarities actually stop. The new pound coin has been introduced in order to combat the huge concentration of counterfeit copies of the old pound coin that have flooded the market – it is said that one in every forty pound coins is actually a fake.
The Royal Mint have introduced several security measures in the design of the new pound coin, most of which are physical intricacies of the coin itself, from the twelve-sided nature of the coin that is harder to recreate than a round pound coin, to the alternating ridged edges, to the £/1 logo on the base of one side of the coin reminiscent of ‘three dimensional’ double images that populated the sticker books of children of the 1980s.
There is however one security feature that the Royal Mint are being particularly cagey about, and that is the feature that they deem to make the coins the most difficult ever to forge. The coins contain within their core a so-called ‘integrated secure identification system’, or iSIS as it is rather unfortunately abbreviated to. This involves the incorporation of a very specific material composition that has a distinctive effect on the electromagnetic signal in a detector. Only the new pound coins will have these materials in their specific amounts and proportions to create a unique fingerprint that can be detected by electromagnetic signal detectors.
The Royal Mint and the security company behind this are understandably secretive about the exact materials used to support this technology, but it does mean that another bit of materials technology has had to be implemented to protect this extra security measure. It involves the creation of a specific combination of materials to make a particle that is incorporated within the core of the coin that can be detected by compatible machines.
The average coin is constantly losing mass thanks to erosion from everyday use. While it is not at such a rate that it is detectable, it does mean that over time measured in years, the old pound coin and other coins like it were losing their characteristic markings that added to its unique design. They therefore had to be taken out of circulation fairly frequently. Given the extra effort that has gone into making these new pound coins, frequent replacement would cost the UK a lot of money. The Royal Mint have therefore used a method of plating they call aRMour (the RM presumably capitalised for the Royal Mint), that means that the plating required to give the coins their colour and robustness is applied in one step, resulting in a single layer of an alloy being deposited on the surface. As a single layer is strongly bonded to the core of the coin, there is less chance of loss of the protective layer compared to the old pound coin, which was plated with many layers that could chip off through erosion.
As the old pound coin lost on average a one micron layer of material each year, this meant that the coins quickly lost their distinctive outer layer, reducing their useful life span. This new method of plating creates a single layer that is more robust and 25 microns thick, meaning that the coins will not need to be replaced as frequently, making this combination of safety features and materials design one that is created to last for a long time.
Thanks to some mystery materials science and some nifty electroplating methods, it looks like these high-tech new coins will be around for the long haul - or at least until those naughty forgers brush up on their materials science and engineering skills!
