High-Quality Expanded Gamut Breakthroughs
Nothing is like it used to be. Even the feeling of standing next to a flexo press on a print shop floor has changed. In the past, you could feel it in your bones that the flexo machine was running as fast as 1,500 fpm, and the vibration caused by bouncing was hammering the floor and making a terrible noise as a plate kept hitting against an anilox or a CI drum. Today, the feeling is calm and quiet—no bouncing or noise, although the machine speed is the same or even higher.
drupa 2016 changed a lot in flexo. There, we saw that a flexo press can be packed into a smaller floor space than before and still be able to reach great speed and excellent quality. The “Petfood” EG design collaborative project produced by Marvaco, SOMA and Flint Group (see Image 3) was one of the event’s best examples of the ultra-high and photo-like quality, the high speed and the reduced bouncing of which flexo is now capable.
The job was produced live at drupa with a very high image resolution of 254 lpi on Flint Group nyloflex 0.45 plates using Esko Full HD technology, printed on 12-μm. PET in 1,200 fpm using a SOMA Optima2 press. The multi-color separation of the image was done with Esko Equinox in CMYK+GV (EG CMYK with green and violet inks), six process colors and white. The SOMA press used the company’s Anti Bouncing Control mechanism, so we dared to make a design without a typical stepping of the lanes. Aniloxes were 1,523 lpi and 1.8 bcm, which still created smooth and strong solids (black density of 1.7), with vignettes fading completely to zero.
It was an impressive moment and a breakthrough that proved high-quality EG can be easy. There was no question if the “Petfood” job was close to the quality of gravure printing. The visitors who saw the samples at different partner booths commented that “This cannot be flexo, this must be gravure”; even gravure printers were claiming it had to be gravure, not flexo.
The Efficiency of Gang Printing
The “Petfood” print at drupa launched a partnership and further co-development between Marvaco, SOMA and Flint Group, who were motivated to showcase additional examples of high-quality EG flexo printing with even higher efficiency.
As expanded gamut is often considered a 7-color technology, we wanted to demonstrate the “Petfood” case print in six colors. But for the next show, Labelexpo Europe 2017 in Brussels, Belgium, we wanted to boost the color space even further and increase productivity. To increase the challenge and visuality, we added silver as the eighth color to create metallic shades and made a gang print design. This resulted in a collection of nine different artworks on the same sheet, containing more than 30 different color shades (see Image 4).
The material was now even more challenging: the self-adhesive laminate had a higher thickness (133-μm.) due to glued PP and the release material. Meanwhile, we had already experimented with EG printing in real life and seen that 178 lpi on the plate would work without problems. Due to this, the demo was once again printed in 178 lpi with Flint Group nyloflex 0.45 plates and processed with Full HD flat top dot technology, where the color separation was done with Esko Equinox. We printed it on a SOMA Optima at 1,150 fpm with 2.1 bcm anilox.
The design looks like a line work, but everything was created by rasterizing the images using EG CMYK+OGV+silver. Register accuracy is always a critical factor in executing multi-color separation, but modern, directly driven CI flexo presses like the SOMA Optima have constantly shown they can maintain register, and even smallest negative texts up to 4-color multi-color separation are possible. These experiences have led us to using multi-color separation in real life for small texts and even bar codes.
What Have We Learned?
It has been said the anilox is the heart of the flexo machine. The anilox was a critical choice in the “Petfood” job as well. To make the ultra-high linescreen count of 254 lpi on plate, the anilox needed to have a high count, too.
Therefore, we selected a 1,523 lpi anilox. When the anilox line count goes up, the volume of anilox cells comes down. To print the finest details and smallest dots while still getting perfectly strong solids, we needed an ink transfer that was both low and good. When we selected a very low 2.1 bcm volume, we knew we needed a new kind of elongated cell engraving. The traditional 60 degree hexagonal engraving was not able to deliver the needed ink transfer. Later, we learned that an even lower linescreen will fulfill our needs and currently we are using elongated cell-shaped aniloxes with approximately 1,300 lpi and 2.1 bcm.
Of course, the ultra-high linescreen anilox is very demanding for ink specs, but we knew that the latest developments of various ink suppliers could handle it. Our tests had also shown the older variants of ink recipes were not performing that well. In high-quality flexo, the ink needs to dry very slowly so that the very thin ink layer will not dry on the plate. Based on our experiences, we can state that if there is a printing problem, some part of the process has not been updated. With modern tools, you can eliminate most printing problems.
Printing a Line Work Job or a Screened Job?
What is the biggest fear in making a simple line work in screen? The questions faced here are usually the same: How do you maintain the register in three colors in negative text, and will the brand color be consistent when made via color separation?
To use high-quality EG successfully, you need to control the details and tolerances, which means the print process with its deviations must be controlled, and you will need an experienced professional to make the prepress.
To demonstrate all this, we at Marvaco, with partners SOMA and Flint Group, completed a high-quality EG project for SOMA’s Flexo Challenges Conference 2018, held in the Czech Republic in May. We collected 18 designs into a co-print where more than 30 colors were printed with only seven plus one colors—in one pass. We collected various challenges into a single design and demonstrated how the colorful design could be printed with only CMYK+OGV+white on BOPP.
Smooth solids, small texts, very fine details and elements with tight tolerances were all brought together in a single design. The live demo showcased designs like those which have been printed with gravure in the past. The linescreen was 178 lpi, which we consider to be the new standard in high-quality EG flexo.
As we all know, EG systems do not cover 100 percent of the full PMS spectrum, nor is it practical to build all color elements (e.g. brown texts) from multiple process colors. In any case, the system is suitable when the colors and elements can be kept within acceptable tolerances. EG systems are even able to expand and stabilize process printing over the CMYK gamut with a remarkable increase in quality and productivity in many products.
I hope this article has inspired and motivated you to take the next steps toward high-quality process printing with high overall equipment effectiveness (OEE). We have seen we can reach the densities and details that were not possible earlier and our next steps are to replace an even bigger part of gravure printed products with EG flexo.
About the Author: Kai Lankinen has 20 years’ experience in high-quality flexo printing, and has been responsible for large-scale print operations, as well as their development. Since 2004, he has been researching multi-color process printing, and for the last 10 years, he has managed a highly awarded packaging prepress company which has seven productions sites in Northern Europe and serves packaging printers and brand owners all over the world. Kai is a pioneer in modern high-quality EG process development with partners from printing, press manufacturing, ink and plate production, and anilox and tape production.
Marvaco has been awarding printers and print solution suppliers with Expanded Gamut Printing (EGP) Partnership Certificates since 2015. The purpose of the Marvaco EGP Partner Certification is to make it easier to recognize suppliers who can deliver EG print process tools, and to raise awareness of all available fixed palette systems.