# Optically variable ink

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{{Short description|Anti-counterfeiting measure}}
{{Globalize|date=April 2021}}[[File:Ovi.png|thumb|200px|[50 euro note](/source/50_euro_note) details, seen from different angles. "50" was printed with OVI.]]
thumb|Optically variable ink used in popular USB drives that are often subject to counterfeiting. Taken from 2 different angles.

'''Optically Variable Ink''' ('''OVI''') also called ''' color shifting ink''' is an anti-[counterfeiting](/source/counterfeiting) measure used on many major modern [banknote](/source/banknote)s, as well as on other official documents ([professional licenses](/source/licensure), for example).

The ink displays two distinct colors depending on the angle the bill is viewed at. The [United States fifty-dollar bill](/source/United_States_fifty-dollar_bill), for example, uses color shifting ink for the numeral 50 so that it displays copper at one angle and bright green in another.<ref>{{cite web|url=http://www.sicpa.com/731/764/1860/1911/7512.asp|title=New design for the US $50|author=<!--Not stated-->|website=www.sicpa.com|publisher=SICPA|access-date=24 July 2006|url-status=dead|archive-url=https://web.archive.org/web/20061016041931/http://www.sicpa.com/731/764/1860/1911/7512.asp |archive-date=16 October 2006}}</ref>

OVI is particularly useful as an [anti-counterfeiting measure](/source/Counterfeit) as it is not widely available, and it is used on [security printing](/source/security_printing). One major manufacturer is a [Swiss](/source/Switzerland) company called [SICPA](/source/SICPA) (Société Industrielle et Commerciale de Produits pour l'Agriculture).  Additional suppliers include German company [Gleitsmann Security Inks](/source/E.T._Gleitsmann), [Sun Chemical](/source/Sun_Chemical) (through their Brand Protection Division based in Manchester, UK), and the Swiss company [Printcolor AG](/source/Printcolor_AG), located in Berikon, [Switzerland](/source/Switzerland).

Color-shifting inks reflect various wavelengths in white light differently, depending on the angle of incidence to the surface. An unaided eye will observe this effect as a change of color while the viewing angle is changed. A color copier or scanner can copy a document only at one fixed angle relative to the document's surface.<ref>{{cite web|url=http://www.icao.int/mrtdsymposium/2007/Docs/DIS_ICAO_Montreal_Presentation%202007_final.pdf|website=www.icao.int|publisher=International Civil Aviation Organization|title=3rd ICAO MRTD Biometrics and Security Standard Symposium - 2007|access-date=7 December 2007|url-status=dead|archive-url=https://web.archive.org/web/20081219141857/http://www.icao.int/mrtdsymposium/2007/Docs/DIS_ICAO_Montreal_Presentation%202007_final.pdf|archive-date=19 December 2008}}</ref> It uses finely powdered [pearlescent](/source/pearlescent) [glitter](/source/glitter) or flakes of mica or an electrically insulating material such as resins or plastics with at least two metal-based, optically reflective compounds on top deposited by physical vapor deposition, that cause light interference.<ref>{{Cite web | title=US6383638B1 - Bright metal flake based pigments          - Google Patents | url=https://patents.google.com/patent/US6383638B1/en?q=(glitter)&assignee=Flex+Products+Inc&scholar&oq=assignee:(Flex+Products+Inc)+glitter&page=1&peid=635a2097f07b0%3A182%3A48169008 | access-date=2025-08-30 | website=patents.google.com}}</ref><ref>{{Cite web | title=CN1900178B - Framework or border are provided around the opaque flakes applied for concealed anti-false          - Google Patents | url=https://patents.google.com/patent/CN1900178B/en?q=(glitter)&assignee=Flex+Products+Inc&scholar&oq=assignee:(Flex+Products+Inc)+glitter | access-date=2025-08-30 | website=patents.google.com}}</ref><ref>{{Cite web | title=CN1923912B - Alignable diffractive pigment flakes and method and apparatus for alignment and images formed therefrom          - Google Patents | url=https://patents.google.com/patent/CN1923912B/en?q=(glitter)&assignee=Flex+Products+Inc&scholar&oq=assignee:(Flex+Products+Inc)+glitter | access-date=2025-08-30 | website=patents.google.com}}</ref><ref>{{Cite web | title=US6749777B2 - Diffractive pigment flakes and compositions          - Google Patents | url=https://patents.google.com/patent/US6749777B2/en?q=(glitter)&assignee=Flex+Products+Inc&scholar&oq=assignee:(Flex+Products+Inc)+glitter&page=1 | access-date=2025-08-30 | website=patents.google.com}}</ref> It is similar to paint containing [ChromaFlair](/source/ChromaFlair) pigment.

==Optically variable magnetic ink==

Optically variable magnetic ink (OVMI) has visual effects that are based on the magnetic properties of the ink. When the document is tilted, movement of a bright light stripe occurs and the colour changes. It is usually applied by screen printing. This type of ink is used for the [Euro](/source/Euro_banknotes),<ref>{{cite web|title=Security features - Europa series €100 banknote|url=https://www.ecb.europa.eu/euro/banknotes/security/html/index.en.html|website=www.ecb.europa.eu|date=11 September 2018|publisher=European Central Bank|access-date=12 November 2018|url-status=live|archive-url=https://web.archive.org/web/20181112065935/https://www.ecb.europa.eu/euro/banknotes/security/html/index.en.html|archive-date=12 November 2018}}</ref> [Brazilian real](/source/Brazilian_real),<ref>{{cite web|title=GET TO KNOW THE BRAZILIAN BANKNOTES|url=https://www.bcb.gov.br/dinheirobrasileiro/en/segunda-familia-cedulas.html|website=www.bcb.gov.br|publisher=Central Bank of Brazil|language=en,pt,es-419|access-date=12 November 2018|url-status=live|archive-url=https://web.archive.org/web/20181112223355/https://www.bcb.gov.br/dinheirobrasileiro/en/segunda-familia-cedulas.html|archive-date=12 November 2018}}</ref> and [Russian ruble](/source/Russian_ruble) banknotes.<ref>{{cite web|title=Banknotes|url=https://www.cbr.ru/eng/Bank-notes_coins/banknotes_itm/?PrtId=banknotes_itm&nominal=5000&year=2010|website=www.cbr.ru|publisher=Central Bank of the Russian Federation |language=ru,en|access-date=12 November 2018|url-status=dead|archive-url=https://web.archive.org/web/20181112224537/https://www.cbr.ru/eng/Bank-notes_coins/banknotes_itm/?PrtId=banknotes_itm&nominal=5000&year=2010|archive-date=12 November 2018}}</ref>

==References==
{{Portal|Money|Numismatics}}
{{Reflist}}

Category:Money forgery

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Adapted from the Wikipedia article [Optically variable ink](https://en.wikipedia.org/wiki/Optically_variable_ink) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Optically_variable_ink?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.