Guardian
Guardian is a polymer substrate used by banknote printers and central banks to produce durable polymer banknotes.
Last updated October 21, 2026
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Overview
Guardian is the trademarked name for a specialized polymer substrate developed for the production of polymer banknotes. It was originally manufactured by Securency International, a joint venture between the Reserve Bank of Australia and Innovia Films Ltd. Innovia later acquired the Reserve Bank of Australia's interest in Securency in 2013, leaving the technology and product associated with Innovia's polymer-film business. The substrate is based primarily on polypropylene and other polyolefins. Unlike traditional banknote paper, Guardian is non-porous and non-fibrous. These characteristics make it resistant to water and other liquids, less prone to absorbing dirt, and more difficult to tear once a tear has been initiated. The material also supports transparent or partially transparent areas, which can be incorporated into polymer banknotes as visible security features. Guardian production begins with polypropylene pellets and polyolefin pellets being processed through separate extrusion systems. A central extruder forms the polypropylene core while additional extruders provide the outer skin layers. The resulting molten structure is rapidly cooled as it passes through a forming mandrel. It is subsequently reheated and expanded into a large tube, then collapsed by convergence rollers into a flat, biaxially oriented polypropylene sheet. This base film is identified by Innovia as ClarityC. The base sheet is then converted into the Guardian substrate. Multiple thin opacifier layers are applied to both surfaces, while masks preserve selected transparent portions. These coatings provide the material with its characteristic appearance and texture, protect it from soiling, and increase its overall thickness. During conversion, resins and solvents generate volatile organic compounds; the production process uses thermal oxidation to combust those by-products. The treated substrate may then be printed with security designs and combined with holographic security foil before being cut into sheets and securely transported to banknote printers. Guardian is not itself a currency or a finished banknote. It is an upstream security-printing material supplied for incorporation into banknotes commissioned by central banks and issued by monetary authorities. The material has been associated with commemorative and circulating polymer notes produced for countries and territories including Indonesia, Kuwait, Malaysia, Sri Lanka, Northern Ireland, Taiwan, Brazil, China, the Solomon Islands, and Mexico. The cited examples span the 1990s and 2000s, demonstrating the product's role in the early international adoption of polymer banknotes. The brand's positioning is therefore technical and institutional rather than consumer-facing. Its value proposition rests on durability, resistance to liquids and tearing, long service life, printability, and the ability to support transparent security windows. Because purchases are made through banknote-printing and central-bank procurement systems, Guardian's market visibility is generally lower than that of the currencies printed on it. Publicly available material identifies its manufacturing history and technical characteristics but does not establish a separate headquarters, founder, public listing, or detailed corporate leadership structure for the brand itself.
History
Guardian emerged from the development of polymer-film technology for banknote production. The product was originally manufactured by Securency International, a joint venture established between the Reserve Bank of Australia and Innovia Films Ltd. This ownership structure connected the material to both central-bank expertise in currency security and Innovia's industrial experience in polymer-film manufacturing. The technology was designed to replace or supplement conventional cotton-based banknote paper with a substrate that could withstand more demanding handling conditions. Guardian's polypropylene-based construction is non-porous and non-fibrous, giving it resistance to water and other liquids and helping banknotes remain cleaner during circulation. The substrate also has a higher resistance to the initiation of tears than paper. Its transparent regions provide an additional design opportunity for banknote authorities, allowing security windows and related features to be integrated into the note rather than added only through conventional printing. Manufacturing involves several tightly controlled stages. Polypropylene and polyolefin pellets are melted and extruded into a multilayer film. The molten material is rapidly cooled, reheated, and expanded before being collapsed into a flat sheet by convergence rollers. This produces a biaxially oriented polypropylene base film known as ClarityC. The film is then coated with thin opacifying layers. Masking is used to keep selected sections transparent, while the coatings protect the substrate and give it a suitable surface for subsequent printing. The conversion process also involves solvents and resins, with volatile organic compounds treated in a thermal oxidizer. After coating, the substrate can be printed using security-printing equipment and combined with holographic security foil. The finished material is cut into sheets and sent in secure packaging to banknote printers. Guardian therefore occupies a specialized position between polymer-film manufacturing and high-security currency production. It is not a consumer product and is not sold as a finished financial instrument; its customers and users are primarily banknote printers and monetary authorities. The product became associated with the international expansion of polymer banknotes. Reference material identifies Guardian-based or Guardian-associated banknote production for commemorative issues in Indonesia and Kuwait in 1993, Malaysia and Sri Lanka in 1998, Northern Ireland and Taiwan in 1999, Brazil and China in 2000, the Solomon Islands in 2001, and Mexico in 2009. These examples illustrate the gradual spread of polymer currency technology across Asia, Latin America, the Pacific, and other markets. In 2013, Innovia Films completed the acquisition of the Reserve Bank of Australia's interest in Securency International. This transaction changed the corporate ownership context surrounding the technology, although the available reference material does not provide a complete chronology of product renaming, manufacturing sites, or subsequent corporate structures. Guardian's historical importance lies in its contribution to the industrialization of polymer banknotes: it combines a durable plastic substrate with printable surfaces, transparent areas, and security features suited to central-bank currency programs.
- 2013
Innovia completes acquisition of Securency interest
[1]Innovia Films completed the acquisition of the Reserve Bank of Australia's stake in Securency International, changing the ownership structure around Guardian manufacturing.
- 2009
Mexican commemorative issue
[1]The Bank of Mexico issued a commemorative polymer banknote associated with Guardian.
- 2001
Solomon Islands issue
[1]The Central Bank of Solomon Islands issued a commemorative polymer note using the substrate technology.
- 2000
Use in Brazil and China
[1]Brazil and China issued commemorative polymer banknotes associated with Guardian substrate production.
- 1999
Adoption by Northern Ireland and Taiwan
[1]Commemorative polymer notes were issued by Northern Ireland's Northern Bank and Taiwan's central bank using the technology.
- 1998
Further adoption in Malaysia and Sri Lanka
[1]Malaysia and Sri Lanka issued commemorative polymer banknotes using the substrate technology associated with Guardian.
- 1993
Early commemorative polymer-banknote use
[1]Reference material identifies Guardian-associated polymer substrates in commemorative banknotes issued by Indonesia and Kuwait.
Products and positioning
A specialist, institutional-grade polymer substrate for secure, durable banknote production, positioned around liquid resistance, tear resistance, cleanliness, printability, and transparent security features.
Polymer banknote substrate
Guardian polymer banknote substrate
Guardian is a multilayer polypropylene-based substrate designed for high-security banknote production. It combines a biaxially oriented polymer base with thin opacifier coatings and selected transparent areas. The material is non-porous, resistant to liquids, and more resistant to tear initiation than conventional paper, while remaining suitable for security printing and the integration of holographic foil.
Base polymer film
ClarityC
ClarityC is the biaxially oriented polypropylene base film produced before the final opacifier and security-feature conversion stages. In the Guardian manufacturing process, it forms the underlying sheet that is subsequently coated, printed, and prepared for delivery to banknote printers.
Controversies
2020
Guardian apologizes over article about coronavirus death
The Guardian issued an apology over an article suggesting that a 21-year-old woman from High Wycombe may not have died of coronavirus. The apology followed the publication of the article, which raised questions about the cause of the woman's death. The Guardian acknowledged the article and apologized for it. No further details about the article's content, the woman, or the outcome were provided in the source.
Brand decisions
2013
Innovia takes full ownership of SecurencyM&ABackground
Guardian had been manufactured by Securency International, a joint venture involving Innovia Films and the Reserve Bank of Australia.
Action taken
Innovia Films completed the acquisition of the Reserve Bank of Australia's interest in Securency International.
Aftermath
The transaction placed the technology within an ownership structure controlled by Innovia Films, although the available reference does not specify later corporate or product-brand changes.
Recent events
Guardian apologizes over article about coronavirus death[3]
Reported:
The Guardian apologized for an article suggesting that a 21-year-old woman from High Wycombe may not have died of coronavirus.
Sources4 sources
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