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FLEXO Magazine : January 2010
www.flexography.org JANUARY 2010 FLEXO 9 THE FLEXO CHALLENGE Speaking to unique challenges in controlling color for flexo, Jay Sperry, Clemson University, stated, "All this color man- agement is great, but it's no good if the anilox isn't clean." Moments later, Sperry noted that this situation works in reverse, saying that good color management techniques can help identify when an anilox needs to be cleaned. Another challenging factor in flexo, according to Sperry, is the variety of ink systems, which is a direct result of the vast array of end use applications. To predict color on press, Sperry insisted that flexogra- phers calibrate hand proofers to the press anilox. He also recommended reducing anilox inventories to include just a few volumes for each color, as well as introducing a thorough anilox care program. Perhaps the larg- est struggle in color managing flexo, Sperry observed, is matching across substrates. To accomplish this, Sperry quoted a formula attributed to Mark Samworth of EskoArtwork, namely using ΔE as a measure of dot gain. For example, if the ΔE between the substrate and solid area is 60, then ΔE between the target 50 percent would be 30, as so forth. This information should then be integrated into a RIP. Sperry admitted that this technique does not work with high- lights. To compensate, he suggested using soft mounting tape, and using screening to clean up solids. He also advocated the use of near neutral calibration for process colors, and incorpo- rating expected levels of dot gain into a contract proof. STANDARDS & FIRST "While FIRST is not a book of standards, it does reference them," proclaimed Tuccitto on Tuesday, Dec. 8, concluding the three days of Color Management Conference. He then intro- duced Pat Pavia of world-renown toy manufacturer Mattel Inc. Pavia explained the importance of standards and consistency to his operations. "In the toy industry, we have licensors who are much tougher [on color] than us." He told attendees, "I don't care what standard you use, just make your pressroom stable." Later, he added, "Those who want to be competitive must correct problems and fix weaknesses." Smiley took the podium next to talk about international standards, with Mazur and Tuccitto chiming in to relate his comments back to FIRST. Smiley began by noting that, for the past four years, ISO (International Standards Organization) has been revising document 12647-6, which offers procedures for halftone reproduction for flexography. One goal is to ensure that results are compliant with 12647-7---the equiva- lent standard for proofing. FIRST, he revealed, recommends using an ISO-compliant control bar on any given proof, and also defines ANSI viewing conditions in both the print and prepress section. "When your customer hands you a job, they must tell you how they want it printed," said Mazur. This can be via ICC profiles, a proof or G7 curves. He identified the three FIRST- recommended methods of compensation calibration that can help ensure the print matches: 1. Dot Gain Compensation 2. Near Neutral Density Calibration (G7) 3. Profile to Profile Conversions Dot gain compensation, according to Mazur, is easy, but does not consider all of the variables. Near neutral calibration is closer, as it looks at both dot gain and how colors overprint. Profile to profile conversions, are the best and the easiest to implement. However, there is concern over dealing with minimum dots, maintaining the integrity of spot colors and not introducing contaminating colors into saturated colors. There is software to deal with all of these issues, but the prepress sup- pliers have been slow to adopt this technology in flexography. Smiley observed that, in increasing numbers, PDF files are being used in the printing industry. Tuccitto cited FIRST prepress section 8.1, which named acceptable and unaccept- able file formats. Section 8.2, he recalled, discusses PDF files, and noted that print outcomes can only be as good as the quality of the file prepared. Or, in other words: "garbage in, garbage out." ISO 12647-6 contains a section on printing aims. Smiley explained this part to attendees, which, in essence, says that each process is unique and may be better suited to different applications. Print buyers should be aware of the strengths and limitations of flexography. From here, Tuccitto launched into a conversation about FIRST methodology. The book, he said, supports the methodi- cal approach to process control outlined in CGATS TR 012- 2003. "While it is true that each organization employs its own workflow based upon its individual needs, there are many common elements and certain fundamentals to flexographic printing that are universal," he stated. He then noted that, despite being the smallest of all the sec- tions of FIRST, communication is the single most important. Next, Tuccitto outlined FIRST procedures for optimization: • Establish Objective • Define the parameters and team • Layout pressrun • Record run conditions • Measure, Measure, Measure • Analysis of the Data He also stressed the importance of letting press operators and similar staff be a part of the data analysis process. Mazur pointed out that while FIRST references ISO ink standards, the actual FIRST specifications differ slightly. This leads to variation and confusion throughout the industry. "There can be only one C, M, Y and K standard," he pro- claimed. "While certain printing processes may not be able to achieve those standards as well as other printing processes, it should not change the standard. How close you come to matching the standard should not be used as a reason to change the standard." FTA TODAY
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