The first is that, as the growth in production volumes declines, central banks are having their banknotes printed on more durable substrates in order to extend banknote life in circulation and, thereby, reduce medium- to long-term printing costs.
Industry estimates suggest that banknotes printed on polymer substrates, for example, cost twice as much to produce as paper banknotes, but last three to four times longer. This was certainly Australia's experience in the late 1990s, the first few years of printing our banknotes on polymer.