CSIRO

Most Americans would be very upset to find a $50 bill in the pocket of a pair of jeans that had just gone through the wash. If you lived in New Zealand, however, this would be much less of a problem. New Zealand is one of more than 20 countries that use currency made from polymers, and a little soap and water is actually good for these bills.

Polymer banknotes don't wear out as fast as paper money, especially in countries with warm, damp climates. They do not absorb dirt or liquids, and their surfaces are much less conducive to bacterial growth than paper bills.

New Zealand has had polymer banknotes since May 1999. In a press release from the Reserve Bank of New Zealand, Currency Department Chief Manager Brian Lang stated, "Probably the only thing that people will notice, apart from the distinctive feel of the notes, are that the colours are brighter and the font is more modern."

Durability and washability are only two of the reasons for making the conversion. Staying a step ahead of counterfeiters is another. Many of the new polymer notes have clear windows that contain embossed printing and hard-to-replicate images.

During Indonesia's financial crisis of 1997 and the downfall of the Suharto government the following year, counterfeiting was rampant. The problem worsened in 1999, during the bloody warfare that accompanied East Timor's secession from Indonesia. Indonesia issued polymer Rp 100,000 bills in 1999, and currently circulates both paper and polymer bills.

Vietnam "went polymer" in December 2003 "to make the money structure more reasonable and to better fight against counterfeits", according to Governor Le Duc Thuy. Referring to the waterproof notes, he said, "People selling vegetables and fish in the market will be very happy with this money."

Vietnam uses Australian-made banknotes that were developed by the Reserve Bank of Australia and CSIRO, an Australian research institution. The notes are made with the Guardian polymer that is marketed by Securency Pty. Ltd., a joint venture equally owned by the Australian Reserve Bank and UCB S.A., a multinational company based in Belgium.

Guardian is a type of biaxially oriented polypropylene. Typical polypropylene, the type of plastic marked with a recycling symbol number 5, is used for yogurt containers and bottles for medicine, ketchup, and syrup. Sheets of biaxially oriented polypropylene have been toughened by stretching them in two directions, causing the chainlike polymer molecules to line up along the same direction.

In the early 1980s, DuPont developed a form of its Tyvek polymer for the American Banknote Company to use in making currency. Costa Rica, Haiti, and the Isle of Man (UK) issued Tyvek banknotes, but they had to stop producing them because they didn't hold up very well. The ink tended to fade and smudge, making the banknotes look like forgeries. Also, the corners of the notes tended to delaminate, or peel apart. In Costa Rica, peeling the banknotes into "half notes" was a popular pastime. Tyvek banknotes are now collector's items.

Here in the U.S., we're probably going to stay with paper money for the time being. The Treasury Department recently issued new $20 and $50 bills with a whole host of anti-counterfeiting features, and new $10 and $100 bills are scheduled to follow later this year. If you put one of these bills under an ultraviolet light, however, you can see that polymers have made an inroad into U.S. currency as well. The new bills have a polymer thread beside the portrait to discourage counterfeiting.

This article first appeared on January 31, 2005.