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FLEXO Magazine : July 2014
The White Ink Matrix A Multivariate Analysis for Optimum White Ink Transfer Marek Skrzynski D espite our industry’s best efforts, brand owners continue to express their dissat- isfaction with the “weak” or “dull” visual appearance of flexographic white ink, especially on transparent substrates. Poor white ink transfer results in pinholing, which can negatively affect the perceived brightness, saturation and color fidelity of all overprinting colors, so this problem goes beyond the appearance of white—it may affect the success of the entire run. In an attempt to compensate for defects like pinholing or mottle, some printers went to great lengths trying to find workarounds, including: • Different aniloxes • Slower press speeds • Double hits of white But these all come with higher costs, production delays and not much improvement in results. White ink was not looking any whiter, unfortunately. Laying The Foundation In 2012, CSW Inc. approached Vice President and General Man- ager Timothy Gotsick at MacDermid Printing Solutions to suggest working together on improving white ink transfer for flexo wide web applications. After consulting with MacDermid’s Global Director of Innovation Ryan Vest and Senior Application Development Specialist David Recchia, all agreed that finding a viable solution to achieve white ink smoothness and opacity would be an invaluable benefit for the entire flexo industry. Both companies were in the middle of existing research and devel- opment projects at the time, so their opportunity to collaborate was deferred for nearly two years. By that point, CSW's R&D team had developed several options for white plate surface treatments and was conducting short press trials in order to identify the best combination of plate material and mounting tape density. "Our results at the time were limited by the existing selection of com- mercially produced plate materials and we were getting frustrated," recalls Mark Buchanan, CSW's plate division production manager. MacDermid was able to respond fairly quickly with additional photopolymer materials selected for this test by Recchia. “The two companies decided to bring these early trials to the next level by designing an experiment to test the following elements of the printing system: plate surface properties, plate durometers, mounting tape densities and anilox volumes,” he explains. “All combinations would be run concurrently on the same press. Our goal was to evaluate all these variables and determine the optimum combination that would 52 FLEXO | JULY 2014 TECHNOLOGY & TECHNIQUES Forum Flashback