If you’ve been out shopping in the past few days you’ve probably noticed a change in your change, with the first release of Australia’s next generation of bank notes made last week.

This is the third time our bank notes have received a major overhaul:

• The decimal currency was introduced using paper notes in 1966
• Polymer notes replaced paper in 1992
• Additional security and accessibility features were added in 2016.

But this doesn’t mean that the printing presses have been gathering dust for the past three decades; the process of printing money is actually an ongoing one.

How often are new notes put into circulation?

Michael Anderson is the RBA’s head of note issue (doesn’t that sound like a cool job?). He says bank notes only last about eight years on average, then the ink wears off or they become damaged and need to be replaced.

Some denominations last a lot longer than others, though.

“The fives have a shorter life because they’re treated more roughly than the 50s,” he says.

“You tend to shove a five in your pocket, but you put a 50 in your wallet.”

Awww, those poor fives. Bet you’ll think twice about where you put them next time.

But it’s not just about replenishing stock; there is growing demand which the RBA must keep ahead of.

“Demand for bank notes is increasing at a fairly constant rate of 5 to 6 per cent across all denominations,” Mr Andersen says.

The RBA also has to keep a level of contingency stock so there is no risk of a shortage when they experience unforseen surges in demand and seasonal fluctuations.

The global financial crisis, for example, triggered a rush in demand for bank notes so the RBA released additional notes.

“We maintain a contingency stock so rather than having fluctuations in demand that mean we have to stoke up the print works, we make sure we have sufficient stock to smooth out demand,” says Mr Andersen.

“When things quietened down a bit they came back to us.”

When will we stop seeing the old bank notes?

The RBA still gets sent paper notes that have been in circulation for decades, so it’ll be quite a while before every single note is updated to the more secure, modern version.

But the majority of old notes, says Mr Andersen, will be removed quite quickly as people withdraw new notes from ATMs and receive them as change from shops, while the old ones are handed in to banks and not released back into circulation.

In preparation for the release of the new $5 note on September 1, the Reserve Bank distributed about 10 million new notes to banks across the country.

“It’s not as though we open up the gates [on September 1] and the trucks go out. They’ve been going out for the past two weeks,” Mr Andersen said.

Good job, Mr Head of Note Issue.

The next note to receive a makeover will be the $10, but we won’t be seeing any of those until the end of next year. This will be followed by the $20, $50 and $100, each spaced approximately a year apart.

What about the poor old bank notes that nobody wants?

When a bank receives a note that it deems unfit for circulation, the note is returned to the RBA who replace it with a sparkly new one.

The old notes are shredded into tiny pieces, like very expensive confetti, which are then melted and turned into pellets.

Those pellets can be used for building components, plumbing fittings, compost bins and other products, so you never know where your old money might end up. At least those old notes can still feel a sense of purpose.

How much does it cost to print a bank note?

Well, it’s a secret. The RBA won’t reveal the cost of production because it’s considered commercial in confidence.

The place that prints Australia’s bank notes, which is a wholly owned subsidiary of the RBA, doesn’t just produce them for Australia though. It also prints and sells bank notes to other countries, and is responsible for printing Australian passports as well.

What we do know is that a whopping $37 million was spent on designing and testing the new generation of banknotes, so you can see why they don’t update them too often.

Each note contains 19 complex layers and the measurements of these are discussed in microns — that’s one thousandth of a millimetre.