These are just some of the growing number of articles detailing how dirty the banknotes and coins in everyday circulation actually are. Bacterial species such as E-Coli and salmonella have been found on banknotes, including polymer notes.

Currently, around 170bn banknotes are issued globally by 165 central banks. Contrary to popular opinion, worldwide banknote production is not decreasing, it is actually increasing annually by 3-5%, so this is not a problem that is going away.

Varnishing paper banknotes was introduced around 25 years ago in response to the new class of polymer banknote substrates. Varnishing results in a thin protective layer printed on both sides of the banknote which increases the life of a banknote. There are now around 48bn varnished notes in circulation.

Most interestingly, banks are now using the varnishing process to explore the use of additives. Due to the well-documented issues with ‘dirty’ money, banks are adopting a ‘clean-note’ policy. One of the additives they are looking at is the use of anti-microbials to combat these issues.

For the past three years, Unilever plc (and now Penrhos Bio) have been working with Inovink; www.inovink.com, a leading developer of additives for the banking industry.

Lactam has been incorporated into a varnish and onto paper and polymer banknotes and it’s effect on bacterial adhesion assessed by an independent microbial testing laboratory.