Of United States Currency
The US Department of the Treasury, United States Mint, and Bureau of Engraving and Printing produce and protect the integrity of the money used in commerce. Legal tender has been in use around the world for centuries. Counterfeit currency and coins have existed almost as long. The security features contained in both coin and “paper” currency range from the visible to the invisible requiring scientific evaluation to determine authenticity. During this unit, students will examine currency and the scientific methods used to protect its integrity. Security features incorporated in United States money range from a raised rolled edge to intricate patterns and ink processes. Some features can only be seen under a microscope or when using special lighting techniques. Many of these features are also contained in currencies from all around the world. Having the assurance that a country’s monetary system is secure is one basis for the public’s trust in their government.
Alloy - A combination of metals formed together (copper/zinc,copper/nickel,
Color-shifting ink - layered ink method that shifts from green to copper when viewed from different angles
Edge-incused inscription - engraved writing on the edge of a coin
Edge rolling - process that produces the raised rim around the edge of the coin
Galvano - an electrotype formed by electroplating a wax form with copper (later filed with lead for strength)
Microprinting - reduced sized printing that is too small for easy viewing and nearly impossible to scan or photocopy (THE UNITED STATES OF AMERICA 20 USA20 below Treasurer’s signature)
Planchet - Blank metal disks used to produce coins
Plastilene - a modeling wax used to create the original coin design (3-12 times finished size)
Reeding - the collar stamping process that the ridges on the edge of coins
Security features - materials and methods incorporated in currency to prevent counterfeiting
Security Thread - plastic strip inside the currency that bears denomination (USA TWENTY) and reacts by glowing green under UV light examination.
Serial Numbers - combination of eleven numbers and letters unique to each bill
Striking - Impacting the blank with a die to stamp the image on the surface
Watermark - portrait imbedded in the “paper” during production