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FLEXO Magazine : July 2014
Is Gray Balance Useless? Pondering Flexo Printing Process Optimization And Considering The G7 Approach Dr. Martin Dreher W hen it comes to technical advance- ments and market growth, flexog- raphy has been the clear winner and has emerged as the dominant package printing process. This will certainly persist throughout the coming years, but there are some goals that need to be achieved to ensure it. One of them refers to the involved cost of prepress. Prepar- ing the files for printing in flexo is a relatively large expense, in terms of time spent, and requires a far reaching specific expertise. The main actuator for this cost situation is the mostly elevated first printable halftone dot that many flexographic printers have to live with. The threatening breaks in vignettes and voids of the mixed colors achievable through autotypical color mixing require a far reaching, process specific retouching of CMYK image files. For that reason it makes sense to work intensively on the reduction of the first printable halftone dot. The German DFTA Technology Center, too, has developed its own technical solution for DFTA members and prints all its internal projects with linear transfer curves—and con- sequently without any process specific adjustments of the respective image files—very successfully. But even as soon as the majority of flexo printers have achieved this— or any—new level of quality, there is another hurdle waiting on the industry’s path to even greater market success. It is not only the elevat- ed first printing halftone dot alone that renders the transfer of existing image files from other printing processes to flexo quite difficult and laborious, it is also the gray balance that adds to this equation. This is where the G7 approach helps. It is G7’s gray balance that is the focus of our attention. Gray bal- ance is the combination of tonal values in the colored process inks cyan, magenta and yellow that yields neutral gray in printing. Because the ratios between these three inks vary over the range of different gray tints, the gray bal- ance needs to be considered two dimensionally (see Image 1). The Gray Balance Gray balance may be considered the main tentpole of image repro- duction and multicolor printing. As opposed to saturated colors, the Image 1: Gray balance of an exemplary print process 46 FLEXO | JULY 2014 TECHNOLOGY & TECHNIQUES