Paradoxically, the vibrant, brightly-coloured packaging on supermarket shelves would be much dullerre without white ink. This isn’t something shoppers think about much, but printing a good, strong white ink layer is a major issue for flexo packaging producers, one with significant impacts on quality, cost and ROI.
White inks perform critical functions in packaging. They prevent the colour of the product tinting the other colours and provide the foundation for the overlying colours, so that they reflect light in a controlled manner, whether printed four-colour process or using the increasingly popular Extended Gamut Process. Consequently, a lot of white ink is used in flexible packaging: it’s typically 50% of the ink spend but around 65% of the ink used.
Flexo has traditionally struggled with printing sufficiently opaque whites because the cell walls in the anilox rolls leave voids in the ink layer, resulting in pinholes, causing colours to show through each other and creating a “muddy” effect. Overcoming this tends to increase cost and decrease press capacity. One way is to use more ink to increase opacity, but unless the pinholes are closed, this uses significantly more ink. It also requires more drying time, reducing press speed and hence capacity and productivity.
Another tactic is to lay down two or three hits of white, using additional printing stations and different anilox rolls to give different lines-per-inch values, create varied patterns and fill the voids. However, this typically consumes 50% more white ink.
Pre-press packaging specialists Reproflex 3 and Roberts Mart, a leading supplier of printed flexible packaging, collaborate on a number of packaging projects and use the KODAK FLEXCEL NX System to overcome these issues.
Tony Rymer, print technical manager at Roberts Mart, says the company turned to FLEXCEL NX in 2014 after customer concerns about print quality using other plates. “We had comments on the lack of colour strength, poor definition and contrast. Before FLEXCEL NX we usually increased the volume with anilox rollers, which increased white usage and used hard mounting tapes, which caused other problems such as barring. Now we lay down only one white yet get more vibrant colours, fine vignettes, excellent dot reproduction, excellent contrast, consistent dot gain and density measurement.”
Reproflex 3 has worked with FLEXCEL NX since 2008. “The system has both print and cost benefits,” says joint managing director Trevor Lowes. “The increased laydown of FLEXCEL NX means we advise print clients to use lower-volume aniloxes to achieve the same opacity. And as well as better quality, they achieve greater efficiency and consistency, running the press at speed, with minimal downtime on cleaning plates. These are real benefits.”
FLEXCEL NX uses Kodak’s NX Advantage technology to create precision-engineered plate surface textures that optimize ink transfer and give smooth, uniform solids and high print densities. Full-amplitude, flat-top dots minimize dot gain and resist over-impression for exceptional consistency and printability, even on re-useable and recyclable materials.