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FLEXO Magazine : July 2011
Technologies & Techniques Adopting Expanded Color Gamut Printing at the Brand sets Packages Apart From Competitors Expanded Color Gamut (ECG) printing has a significant and obvious presence in several grocery categories. The images in those aisles of the supermarket are much brighter, often more complex and generally create more impact than the packaging in other aisles. The greater impact of ECG printing, however, is efficiency. By fully adopting ECG ink sets and replacing spot colors with process builds, flexo printers are saving on makeready and material costs, throwing less away and producing more. There are challenges and confusion about the process for the printer and for the separator that may create resistance in the supply chain, but it may be time to confront those concerns. After all, how often does a brand owner have the opportunity to make packaging designs more eye-catching and save waste in printing them? DEIGN FOR APPROACH Because flexo can print on almost anything, the process is used to print on virtually everything. Every structure brings unique challenges, and each printer devises an approach to solve those difficulties. “ You have to design this for flexo,” has traditionally meant, “ You may have to compromise the ideal, given the approach that I will use. ” In reality, we are designing for the approach, not for the process. For most printers, the easiest and most reliable approach is to use CMYK process inks for images and dedicated print stations for each spot color. Flexo CMYK process inks are designed to deliver color at adequate strength with a thin ink film using high line count, low volume anilox rolls. These anilox rolls enable printing fine line screens with low dot gain. This means that images will display subtleties and even appear to be continuous tone. With special screening or platemaking techniques, highlights may even fade to zero. Using dedicated pre-matched inks for spot colors simpli- fies color control on press to maintenance of ink viscosity. It requires, however, that inks be changed out as colors change from one design to the next. That change results in ink loss and accounts for a great deal of the solvent use in an opera- tion. Spot colors in large coverage areas are required to have smooth, rich ink coverage, which is often improved by using slightly higher volume anilox rolls. Stronger spot colors can require even greater ink film thicknesses, which may require even coarser rolls. The higher volume anilox rolls in spot colors may require coarse line screen plates for any tints and gradients, which are more visible and harsh, rather than subtle and smooth. The heavier ink film will also deliver a larger “minimum printed dot,” disallowing soft fades and fine highlights. Designing for CMYK + spot flexo generally means mini- mizing screens and maintaining heavy minimum dots in spot colors. It also requires that you: avoid using too many colors for the press, keep fine copy out of colors with heavy cover- age, and anticipate “unwanted third colors” where dissimilar spot colors will meet and trap. ECG INKS For ECG printers, a common set of six or seven process colors is used to render every design. Spot colors are created using screens and combined overprints of those colors. The first and potentially most difficult printer challenge is to establish plate fit, mounting and press register capability to allow three or even four color process builds in text areas designed to run as a spot color match. Another challenge is to select process colors beyond CMYK, where no standards exist. A great resource can be found in the April 2011 edition of FLEXO, which featured a fine study by the FFTA Rossini Scholar Kristen Zeleznik. Addition- ally, the Flexo Quality Consortium (FQC) has a team tasked with testing ink sets and proposing standards. The emerging 42 FLeXO july 2011 www.flexography.org BuiLding LimitLEss COLOrs • By fully adopting ECG ink sets and replacing spot colors with process builds, flexo printers are saving on makeready and material costs, throwing less away and producing more. • For ECG printers, a common set of six or seven process colors is used to render every design. Spot colors are created using screens and combined over- prints of those colors. • Since ECG printing uses a single ink set like CMYK- OGV to build every color, there need be no limit to the number of spot colors in a design. • Optimizing the colors beyond CMYK will require col- laboration with ink and roll manufacturers.