ĭuring World War II, a competition between laboratories to develop the best invisible ink developed between the Allies and the Axis powers. Especially during the wartime, invisible inks were widely used by militaries to hide secret messages and important addresses. Many people and organizations use UV markers to protect and hide sensitive messages from the public. Other applications include retailers marking their items to identify customers who might exchange or return items that were not originally bought from their stores. Moreover, various countries use UV markers to create marks on state issued driving licenses and identity cards to ensure they are authentic. Credit cards are marked with a particular logo or the card type. For example, in the state of Illinois, the lottery tickets are stamped with UV-invisible ink to indicate authenticity. UV markers are also widely used on credit cards or lottery tickets for authentication, to help discourage counterfeiting. It is also sometimes used in identifying whether a document is an original or a copy. Applications Security and authentication Ĭommercially available UV markers are used to mark things for security purposes, such as to check for counterfeit money and mark property in the event of theft for the purpose of identifying ownership. In some cases, people can also use photocopiers to develop UV-visible ink messages, because the scanning head of the machine emits UV light. When the black light falls upon UV-visible ink, it makes the ink fluoresce so that it emits visible light, making the message readable by human eyes. Therefore, UV LEDs are claimed to be completely safe, causing no damage to eyes nor risks of skin cancer. The lamps used have very narrow bandwidth, compared to regular fluorescent black lights. The near-ultraviolet radiant energy is also called black light with a wavelength of 380 nm, which falls just outside the visible spectrum. UV LEDs emitting near-ultraviolet light are used to read messages written by UV markers. All three types contain acrylic monomers which contain a diluent and a photoinitiator to participate in the curing reaction and to respond to UV radiation. There are different types of UV-visible ink: opaque, semi-opaque, and translucent. Modern UV-visible ink uses a fluorescent component derived from materials that glow when exposed to an ultraviolet light. The main components in improvised inks have included dilute laundry detergent, body fluids, tonic water, and vitamin B-12 dissolved in vinegar. This is right at the edge of the visible light spectrum, so you will see a purple glow cast from it, but it is a long enough wave to excite the fluorescent material and reveal the secret message.In the past, the ink used in UV markers has been made from various things such as lemon juice, vinegar, diluted blood, or even urine. This is easiest to see in dim lighting conditions.Ī nice, compact source for UV light is a UV/Purple LED which emits light in the 400nm wavelength. However, when illuminated with a UV light source (sometimes called a blacklight), it fluoresces brightly. Ultraviolet marker pens use ink which lacks colour pigment, so it doesn’t leave a mark visible to the naked eye under normal lighting conditions. Quickly and easily write and view ‘secret’ messages.UV light also effective for checking bank note watermarks.Built-in UV light for easy identification of marked items.Discreet, totally portable security solution.Perfect for the little spy in your household! The UV Security Light Pen can be used to check for watermarks on bank notes and other documents, and the pen used to invisibly mark documents or bank notes or to write ‘secret’ messages. A perfect party gift allowing your children to be really creative with their writing, sketching and drawing.Shine the light on the writing spot to see the message appear like magic!.They can use the UV pen to uncover secret messages.Ĭhildren love forensic spy games and these pens make a perfect addition to any spies collection box. This invisible ink spy pen is a perfect gift for children. This spy pen lets you write secret messages which are only revealed by the built in UV light!
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