Naked Science Forum
General Science => Question of the Week => Topic started by: thedoc on 17/09/2014 10:58:48
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How is money made, and how are the different colours formed?
Asked by Dominic, Newmarket
Find out more on our podcast page (http://www.thenakedscientists.com/HTML/podcasts/naked-scientists/show/2010.03.07/)
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We answered this question on the show...
Diana - So, let’s start with the notes first. How do they survive the wash?
Mark - My name is Mark Cricket and I work for the bank note printers De La Rue. [img float=right]/forum/copies/RTEmagicC_US_money.jpg.jpg[/img]Essentially it starts, not surprisingly, with the paper itself which is manufactured from cotton rather than wood which is used for most of the papers that are used in other applications. The reason that cotton is used is to make the notes more durable against the rigors that they’ll face in circulation with the public and also, when it’s combined with the printing process, it helps to give the bank notes the unique feel which makes them feel different from other printed documents. The process that we use is very old process, quite an unusual process which is not used not for commercial paper production and that enables us really to put in the distinctive tone of watermarks and the metallic strip which we call a security thread which runs through the paper and is inserted when the paper is manufactured. What we then do is we take the paper and it runs through a number of printing processes. The first process which is known as litho puts on most of the colours and provides most of the back of the Bank of England notes and much of the fronts. The second process which is a very unique process used in bank note printing is called intaglio which actually uses an engraved plate and ink basically goes into the engraved effect grooves in the plates and is then forced out under pressure, and that helps to produce a very distinct tactile feel to the notes which again is an important security feature for the public to recognise some of the elements. For example, printed by this process is the portrait of her majesty, the Queen. And then the third main process is known as letterpress and that’s used to put the unique serial number on each note which obviously is used to help keep track of the notes.
Diana - But what about the coins?
Matt - My name is Matt Bonaccorsi and I'm Chief Engraver at the Royal Mint in South Wales. We obviously start off, like any other product, with a design. Once that design is completed, we then have to turn it into a 3D or we call 2.5D object which is the sort of sculpted version that you're going to see on the coin itself. These days, we use a lot of computer CAD sculpting and if you can imagine, it’s a three-dimensional map of the coin on a screen that is 4,000 by 4,000 pixels. That gives us 16 million points of information within that screen and each one of those points is a coordinate and we feed those coordinates into our CNC engraving machine - which is basically a tiny revolving cutter that will then move over a blank piece of steel, following those coordinates. As it works its way around, it gradually builds up a picture of what the finished coin looks like.
Obviously, when we stamp a coin, the stamps that actually impart the design onto the surface of the blank - those stamps, which are called dyes, have to be back to front. So we take our steal piece of tooling with our coin design on it and we press it. We put it under a hydraulic press and squeeze it into a soft piece of steel so we can take a negative impression from that. It’s that negative impression that’s then put on a lathe and turned to the right shape and size to fit into one of our presses, and that’s what will actually stamp the coin itself.
Forgery is obviously a key part of what we do. The metal composition of coins is key to that. The percentages of different alloys that go into coins are very, very closely monitored and very, very closely controlled, so it becomes very difficult to replicate a coin that will read in vending machines or that will look or feel the same as a real coin.
Diana - So notes are made from cotton and some very secret inks; some of which are magnetic, others can only be seen in UV light, and some are only visible when they become warm. Coins can also be protected from forgery using clever design tricks such as a latent feature in the 2-pound coin which is a design that changes as you move it in the light. But their main form of defence is in using very specific metal alloys which are also kept secret of course.
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Making money's easy - you get a job at Royal Bank of Scotland, destroy the bank with a heap of "toxic" assets and then the goverment give you loads of money in a rescue package; you then distibute this amongst yourselves as a "bonus" for doing so well. Trebles (of fifties) all round...
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Did we mention your answer on air? Listen to the answer to this question on our podcast to find out... (http://www.thenakedscientists.com/HTML/podcasts/show/2010.03.07/)
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Money is made if you get a job.
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I found a book of what states to be delarue engraved vignettes and litho elements. They are all art designs with each numbered. Where do I go to find out it's worth.