Making the Most of Specialised Metallic Inks

Alex Stevenson, a member of BCF Sheetfed Group, gives a brief overview of some of the specialised metallic inks available today and the ways they can be used to provide specific application benefits

Recent developments have led to a proliferation of special inks which provide a metal-like lustre, appearing bright and glossy when viewed at one angle while seeming dark and dull at others - a property which has proved attractive in food packaging applications.

Technical advances in ink manufacture have led to these improved products.

In standard, traditional metallic ink formulations the metal particles - usually either beads or flakes of aluminium or bronze - are randomly and irregularly distributed over the substrate, which causes light falling on the surface to be scattered in many directions.

In contrast, the new high lustre pigments contain densely packed flat metallic particles, arranged smoothly over the substrate, causing the incident light to be reflected directly and uniformly from the surface.

The control of metallic inks has traditionally been carried out by either density readings or by the human eye.

Both methods have their limitations: density readings can be affected by different colours and gloss, while control by human vision is open to individual interpretation and fatigue.

Now, the Lustre Measurement System overcomes these problems, by numerically identify the level or brightness of a metallic surface, from which it can provide CIE Lab colour space analysis of printed metallic inks.

Building on the developments in metallic inks, new 'special effect metallic inks' have been created which, by using combinations of ink systems, can provide outstanding printed metallic effects which are of immediate benefit in packaging applications.

Because there are thousands of combinations of inks it is virtually impossible to reproduce a particular effect without the correct combination of inks.

This provides an anti-counterfeit benefit in terms of both security and brand protection - a matter of the greatest interest and value to brand owners and packaging manufacturers alike.

Alex Stevenson is managing director of Intercolor, a specialist manufacturer of high quality inks and varnishes for the packaging industry.

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