A counterfeit banknote detection pen is a pen used to apply an
iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...
-based ink to
banknote
A banknote or bank notealso called a bill (North American English) or simply a noteis a type of paper money that is made and distributed ("issued") by a bank of issue, payable to the bearer on demand. Banknotes were originally issued by commerc ...
s in an attempt to determine their authenticity. The ink reacts with starch in wood-based paper to create a black or blue mark but the paper in a real bill contains no starch, so the pen mark remains unchanged.
Background
Counterfeit banknote detection pens are used to detect
counterfeit
A counterfeit is a fake or unauthorized replica of a genuine product, such as money, documents, designer items, or other valuable goods. Counterfeiting generally involves creating an imitation of a genuine item that closely resembles the original ...
Swiss franc
The Swiss franc, or simply the franc, is the currency and legal tender of Switzerland and Liechtenstein. It is also legal tender in the Italian exclave of Campione d'Italia which is surrounded by Swiss territory. The Swiss National Bank (SNB) iss ...
,
euro
The euro (currency symbol, symbol: euro sign, €; ISO 4217, currency code: EUR) is the official currency of 20 of the Member state of the European Union, member states of the European Union. This group of states is officially known as the ...
and
United States banknotes, amongst others. Typically, genuine banknotes are printed on paper based on cotton fibers and do not contain the starches that are reactive with iodine. When the pen is used to mark genuine bills, the mark is yellowish or colourless.
Such pens are most effective against counterfeit notes printed on a standard printer or
photocopier
A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers ...
paper. The chemical properties of US banknotes printed before 1960 make marking pens useless, resulting in
false positives
A false positive is an error in binary classification in which a test result incorrectly indicates the presence of a condition (such as a disease when the disease is not present), while a false negative is the opposite error, where the test res ...
. One example of this complication taking place happened in 2016, in which a 13-year-old student was arrested by police after she attempted to pay for lunch with a red seal Series 1953
$2 bill after the school's counterfeit pen was unable to prove its authenticity.
Reception
Pen manufacturers claim such pens will detect a great majority of counterfeit bills and are an easy counterfeit detection method that does not require expensive gadgets.
Critical reception
Critics suggest the effectiveness is much lower. Critics claim that professional counterfeiters use starch-free paper, making the pen unable to detect the majority of counterfeit money in circulation. Magician and skeptic
James Randi
James Randi (born Randall James Hamilton Zwinge; August 7, 1928 – October 20, 2020) was a Canadian-American stage magician, author, and scientific skeptic who extensively challenged paranormal and pseudoscientific claims.#Rodrigues, Rodrig ...
has written about the ineffectiveness of counterfeit pens on numerous occasions
and uses a pen as an example during his lectures. Randi claims to have contacted a
United States Secret Service
The United States Secret Service (USSS or Secret Service) is a federal law enforcement agency under the Department of Homeland Security tasked with conducting criminal investigations and providing protection to American political leaders, thei ...
inspector and asked whether the pen works as advertised, to which the inspector replied "it is not dependable."
The Secret Service does not include such pens in their guidelines for the public's detection of counterfeit US currency.
US counterfeiters bleach small denominations and print more valuable bills on the resulting blank paper to evade this test, although
changes to the currency since 2004 have made this method easier to detect. This is one reason that many currencies use different sized notes for different denominations.
False positives
The effectiveness of the pens may be affected by external methods. Simply having a banknote pass through laundry, depending on the soaps and bleaches used, can cause a bill to fail the test when it is otherwise accepted. Additionally, it was discovered that treating a counterfeit note with a dilute solution of
vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...
will cause a false negative: that is, it will respond to the iodine-based ink as though it were made of the same paper as a valid banknote.
See also
*
List of pen types, brands and companies
*
Security printing
Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps, and identity c ...
References
{{DEFAULTSORT:Counterfeit Banknote Detection Pen
Writing implements
Money forgery