What does a percentage increase in gamut size mean, and do consumers see a difference when the print sequence is optimized?
After all, it is a well-known fact that flexo printers cannot reproduce the full range of Pantone colors when using conventional CMYK inks. Yet every day, they are asked by brand owners to reproduce consistent, accurate colors that are not easily obtained with CMYK inks.
In addition, it is not always convenient, cost effective or technically possible to use spot color inks to obtain what the customer requires. Many packages are now designed with eight to 10 colors, utilizing CMYK and an ever-changing variety of Pantone colors that are specific to design families, brands and logos.
By optimizing an expanded gamut (EG) printing sequence based on real, applicable printing conditions, printers can accurately produce a larger number of Pantone colors. With optimized EG printing, shelf appeal and brand recognition are preserved by ensuring production runs are accurate, consistent, repeatable and affordable.
In this article, adapted from my research paper for which I was awarded the first-place 2016 FFTA Rossini North America Flexographic Research Scholarship, proposed models for determining preferred print sequence were utilized and applied to a printed piece through drawdowns and press characterization. Changing the print sequence is found to increase gamut size and the number of achievable Pantone colors.
Altering Print Sequence
The Color Marketing Group estimates the appropriate use of colors increases brand recognition by 80 percent, and 85 percent of the impulse to buy a product is related to color. Kate Goguen, in a 2012 Rochester Institute of Technology study titled “The Influence of Color on Purchasing Decisions Related to Product Design,” revealed that out of 20 purchasing situations, the consumer’s response to color results in a purchase for more than 50 percent of the population in seven situations.
More than 65 percent of purchasing decisions involve color.
So, from these outcomes, we know the colors used in the design of a product strongly influence the consumer’s decision to purchase. However, the capability of printers to reproduce these critical brand colors does not always match the needs of their clients. To match critical brand colors, printers must use conventional CMYK printing, which, according to Matthew Furr’s research detailed in “The Effect of Press Variation on Color Stability on 7-Color and 4-Color Process,” produces a gamut only able to achieve approximately 40 percent of the Pantone library.
While some printers may be able to utilize specially mixed spot color inks, this may not always be the most convenient or cost-effective solution. A wider arrangement of Pantone colors is achievable when orange, green and violet inks are added to conventional CMYK process. The addition of these inks not only has the effect of increasing achievable gamut, but also decreasing costs for printers by reducing the number of makereadies and time to makeready. In order to achieve the best results for printers—and by extension brand owners and consumers—the EG ink sequence must be optimized.
Researchers at Clemson University have proposed a model to predict optimal CMYOGV ink sequence based on four different types of calculations. First, the opacity of the inks used can determine their order by placing the more opaque earlier in the sequence and more transparent later in the sequence. Then, the change in chroma that occurs when orange, green and violet inks are printed before and after their CMY pairs (ex. OM vs. MO) can be examined. The sequence is produced by ordering pairs that produce the greatest chroma.
As a supplement to the examination of overprint chroma, change in overprint hue is analyzed to create the area of an “overprint triangle.” This triangle area demonstrates what happens to the hue and chroma of overprints when the order of orange, green and violet is switched between their CMY pairs. A sequence is then determined by choosing pairs which create the largest triangle area and ordering them accordingly. Lastly, a simplified calculation of gamut volume is used to calculate a sequence by determining which color pairs produce the largest tetrahedron (simplified gamut space) volume. [Editor’s Note: The Clemson University research to which Nina refers and cites in her original report was written by Liam O’Hara, Bobby Congdon and Brad Gasque and published in the November 2016 issue of FLEXO Magazine under the title “Printing in Color.”]
The original researchers proposed that printers can utilize this model by conducting two characterization pressruns. However, this paper explores the application of these models through the process of drawdowns, aiming to provide a solution to further reduce costs for printers, making EG more accessible. In addition, this research aimed to examine the real effect of optimizing and changing print sequence on the way consumers view a product.