Counterfeit banknote detection pens

Definition: Devices that use a chemical reaction to detect some types of counterfeit money.

Significance: Counterfeit-detection pens allow users with no significant training to check paper money for genuineness quickly and cheaply. These tools offer an effective way of combating counterfeiting that is done using computers, copiers, and printers instead of high-technology counterfeiting equipment.

The growing use and availability of technologically advanced devices for reproducing images on paper since the 1990’s has created a new breed of counterfeiters, many of whom are amateurs. According to the U.S. Secret Service, the federal agency responsible for fighting attempts to counterfeit American currency, in 1995 less than 1 percent of the money that was confiscated as counterfeit in the United States was created using devices such as commonly available copiers and printers. By the year 2000, however, nearly half of all counterfeited U.S. bills that were confiscated had been created using such relatively simple methods. This large increase in the use of widely available technology such as color copiers and laser printers in counterfeiting meant that new methods of detection and prevention were needed.

The paper on which real currency is printed contains cotton and other fibers and does not contain significant amounts of starch. The types of paper used for photocopying and computer printing, in contrast, contain large amounts of starch. The chemical element iodine reacts in a predictable way when combined with starch, and this reaction was the basis for the pens that were developed to help detect counterfeit bills. The first such pen received a patent from the U.S. Patent Office on November 5, 1991.

The user of a counterfeit-detection pen swipes the point of the pen across the surface of a piece of paper currency. Instead of ink, the pen contains a solution of iodine that will react with starch, turning dark brown or black. When such a pen is swiped on a bill that was counterfeited using copier or printer paper, an easily recognizable dark mark appears. If the bill has no starch present, the mark made by the iodine solution remains clear or turns a light amber color. Some counterfeit-detection pens have colored dyes added to the iodine solution, so that users can easily tell which bills they have already verified. The color usually fades after a day or so, so that no permanent marks are left on the bills.

Counterfeit-detection pens are important tools in the ongoing battle against counterfeiting. They are inexpensive, usually less than five dollars each, and cashiers and other users need no significant training to be able to use them effectively. They are not, however, generally useful for detecting bills made by relatively sophisticated counterfeiting operations, which are more likely to use paper that is somewhat similar to that used in the printing of legitimate currency. The lack of a significant amount of starch in such bills makes them unlikely to be detected with the iodine solution used in counterfeit-detection pens.

Bibliography

Van Renesse, Rudolf L., ed. Optical Security and Counterfeit Deterrence Techniques. Bellingham, Wash.: SPIE, 2006.

Williams, Marcela M. Handicapping Currency Design: Counterfeit Deterrence and Visual Accessibility in the United States and Abroad. St. Louis: Federal Reserve Bank of St. Louis, 2007.