The Incredible Inks of Espionage
Inks that glow or fluoresce under UV light.
Forgery is a huge problem. In 2012, an estimated $220 million of counterfeit cash was circulating in the U.S. Luminous inks are used widely in the security field for preventing forgery of high value documents such as passports, banknotes and ID cards.
At the end of the American Civil War, ⅓ of all American currency was counterfeit.
3,028 people were arrested for counterfeiting US currency in 2011.
In 1995, less than 1% of US counterfeits came from inkjet printers.
Ink that becomes visible after being exposed to a stimulus.
Types of Invisible Ink
1. Organic Fluids
Heat + Acid
Acid weakens the paper, causing it to darken or burn when heated
2. Sympathetic Inks
Agent + Reagent
Ink is Invisible until reagent reacts chemically with agent
3. UV-Visible Inks
UV Light + Fluorescent Ink
Ultra Violet light triggers chemical reaction with ink
Inks whose color is altered due to a change in temperature.
Types of Color Changing Inks
Change color in response to variations in temperature
Change color in response to exposure to UV light