Inovinks’ New IR Pigments – More than a Mirage

Infrared (IR) is part of the electromagnetic spectrum that lies immediately beyond red light and is therefore invisible to the naked eye. Because of this, IR inks are widely used in the banknote industry to create covert features that are both highly secure and machine readable, particularly by high speed systems.

The IR ink was for many years based on carbon black and as such was camouflaged behind black ink, the hidden feature only being visible under IR radiation. But the inherent dark colour of the carbon black limits the choice that designers have when choosing the colour of the base ink. Over the years, research has been undertaken to improve infrared absorbing pigments, one of the main objectives being to find materials that were IR absorbing, yet light in colour.

This aspect has been improved with the use of lighter colour machine-readable materials, but the amount of material required to be added to banknote inks can be significant, thereby making the finished infrared absorbing feature much more expensive This also impacts on sustainability goals for central banks because so much active material (usually metals) is required. Furthermore, the use of rare earths as an infrared machine-readable security feature should be discouraged because of the social and environmental repercussions of rare earth mining.

The holy grail for researchers has always been to find a more sustainable, colourless infrared absorbing material with improved efficiency through low pigment loading, flexible enough to be incorporated into any banknote printing process (including offset), and at the same time having infrared characteristics capable of being read across the entire cash cycle, in any territory.

UK-based Inovink claims to have achieved all of this with its range of recently patented infrared absorbing pigments known as mIRage.

According to Inovink, mIRage is a highly efficient material loaded as low as 2% in intaglio inks and as low as 5% in offset. The flexibility of printing methods now permits issuing authorities to specify mIRage as an infrared absorbing machine-readable feature when intaglio printing is not available, such as banknotes printed with intaglio on one side. The feature can be printed in intaglio one side and via offset printing on the other.

The very pale colour of mIRage when printed in a clear ink allows the feature to be hidden or printed ‘invisibly’, in what Inovink terms a first for infrared absorbing pigments.

Finally, the mIRage feature is detectable by current BEMs and high-speed sorters.

Inovink states that its mIRage pigments are available by licence in an open process to central banks, printers, ink and substrate manufacturers.