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FLEXO Magazine : February 2014
IMPLEMENTING PENTACHROME— STEP 4 Step four consists of loading the fin- gerprint’s ICC Profile into a specially de- veloped tool we call the “PatchFinder.” It stores all the values of ink percentages for the 875 color patches in the chart of our example, related to the actual location in the color book, defined by coordinates. Once the theoretical build found by software is loaded into the tool, it finds the closest patch in the actual color book (E45 in the example in Image 7), which can then be visually com- pared to the target color and make the final decision of either using it directly, choosing a different one or interpolating between two according to the desired results and tolerances. In our experience, this step of being able to visually see and compare what will actually be printed on the press is crucial. The theoretical values found by software—by themselves—are not enough to guarantee a successful color conversion, since they leave an import- ant margin of uncertainty about the ac- tual results on the pressrun. By the time you’re on press, it can be too late or too expensive to make corrections. In the special case of some graphics that have solid outlines and/or bigger areas in black (like Mickey ’s ears in Im- age 3) we reinforce with one extra solid dark color present in the graphics or a more traditional under color addition of CMY—depending on the case—and play carefully with trapping and over- print in prepress to avoid misregistra- tion issues on the press. IMPLEMENTING PENTACHROME— STEP 5 Finally, once the right builds to rein- force all colors are carefully chosen, they can be used to automatically replace the original inks of the graphics, if the appropriate prepress software for multicolor conversion and ink replace- ment management is available. This can be also done manually or semi automatically if the graphics are not complex. To avoid moire, screen angles can be managed based on the previously mentioned premise of avoiding mixing complementary inks because of the risk of increased grayness, which works against color saturation and vibrancy. Thus, greens can have the same angle as magentas, blues as yellows and oranges as cyans because they never mix. Trapping should be set up using generous values adequate to the char- acteristics of the substrate and favoring overprinting and under color addition whenever possible. In our experience a minimum dot of 8 percent is safe, considering the abrasive characteristics of non woven substrates that can affect smaller dots on the plates, and the total Image 9: A test done on press shows the difference between standard surface impression on a non woven material (left) and color reinforcement using Pentachrome to achieve more vibrancy (right). www.flexography.org FEBRUARY 2014 FLEXO 45