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FLEXO Magazine : December 2012
correctly. So, the committee followed a recommendation from Esko and each converter was asked to use the stan- dard ANSI-CGATS IT8/7.4 CMYK test chart and run the chart three times, substituting an extended gamut color for one of the standard process inks. In addition, ESKO developed a template for Microsoft Excel14 to accept the color readings from the template and generate the gamut increase. Figure 3 shows an example of the template. Representative sheets from a pressrun were sent to the committee and all color readings were made using an X-Rite EyeOne-IO scanning spectrocolorimeter. All readings were made using a single instrument by the color team at R. R. Donnelley. The results of those comparisons are summarized in Table I but the full data set can be obtained from the FTA. CONCLUSIONS There are some general conclusions that can be made without knowing the exact increase in gamut that may be achieved in any specific printing process. First, ECG is not a panacea for the costs and problems of packaging printing. Any given spot color can be tested against an ECG primary set by passing the CIELAB values through the ICC profile. If the predicted tones of the primary inks are equal to, or greater than, the full tone value, or if they are flagged by the color management method as being out of gamut; then it will not be possible to produce that spot color by process printing. Such "out of gamut" colors can be identified to the print buyer and the color may be negotiated to allow a color that is within the gamut to be substituted. Second, process color printing is not as easy as line color printing. Publication printing has very large tolerances, not because the printers or print buyers do not care about money; but because they have learned over the decades that it is not easy to hold tight tolerances from day-to-day or even from be- ginning to end of a long run. Uncontrollable parameters, such as ambient temperature, machine frictional temperature, humidity, dielectric constants, solvent pickup / absorption all can affect how the ink is picked up or transferred. Third, the ECG ink set must be capable of maintaining the full functionality of the package. So, if a spot color ink was doubling as a lamination adhesive, the ECG ink must also be able to do so. This may further limit what pigments and products can be used on that converting line. Switching between surface printing and reverse printing will be more difficult when using an ECG ink set. The inkmaker can help in selecting the right level of customization for any given ink set, but the expectation that one ink set will print everything that was printed previous with line colors is not realistic. As a result, it has generally been observed that there is very little saving in ink consumption and costs in ECG printing over spot color printing. Cost savings have been reported www.flexography.org DECEMBER 2012 FLEXO 19 Experience the science behind the service with Proline® anilox rolls Praxair Proline® laser engraved ceramic rolls deliver quality your printing operation can depend on. Whether you need extended life, improved ink laydown, better opacity, or more repeatable print results, Praxair Proline® series of engravings is for you. Our ART (Anilox Reverse Technology) and REV (Revolutionary Engraving) cell shapes and confgurations continue our history of technical innovation to the fexographic industry that began with the introduction of the frst laser engraved ceramic roll to the printing industry almost 30 years ago. You can see the results every time the press rolls. Improved printing quality. Consistent reproduction. Reduced maintenance downtime. And, better proftability. www.praxair.com/printing Call 1-800-234-3131 for information on how we can help your business.