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FLEXO Magazine : April 2011
Technologies & Techniques Traditionally, the number of colors used determines the cost of each job. Jobs are priced based on CMYK and the addition of spot colors. This charge includes the ink and the cleanup and set- up of that unit. An expanded color gamut system can be more efficient because of its defined ink set, which will require no changeover of inks and can potentially print an unlimited number of spot colors. Some may also argue that an expanded color gamut system also uses less ink because spot colors are formulated on press, allowing buyers to save on ink. For an expanded color gamut system to provide cost savings, it is necessary to define ink bases and sets. Providing information on how colors will transi- tion into expanded color gamut at early stages in the graphics workflow will ensure that established production sys- tems will satisfy expectations. The ink bases, therefore, have been selected using a combination of Flexographic Image Reproduction Specifications and Tolerances 4.0 (FIRST) and consulting with several ink manufacturers and providers. The ink pigments were used to create four expanded color gamut ink sets that are printed using flexographic printing equipment on specified sub- strate while using an ultraviolet inking system. The enhancement to the color gamut and the ability to reproduce spot colors can be evaluated with the differ- ent pigment options provided. Ink bases have been selected in reference to FIRST and consulting with several ink manufacturers and providers. The inks have been grouped into four seven-color process sets, including cyan, yellow, magenta, black, green, violet and an orange or red pigment. These ink sets have been printed under calibrated con- ditions on SF 55# Cast Gloss label stock utilizing an ultraviolet inking system. Data sets and profiles have been cre- ated for each ink set combination using an IT8/7.4 calibration target. INK SELECTION The beginning stages of this experi- ment entailed thorough research on the ink bases most commonly used in the flexographic package printing market. An initial reference to FIRST set the path for distinguishing appropriate pigments to evaluate. Further investigation with the following ink manufacturers and provid- ers allowed for additional pigments to be considered: Environmental Inks and Coat- ings (now part of Siegwerk), Flint Group, Siegwerk and Sun Chemical. A concise chart is provided in Table 1. To determine which advised ink bases are most appropriate for expanded color gamut, several factors were taken into consideration. The first order of opera- tion was to choose pigments with hue angles in the regions desired. When looking to a color wheel, it is clear that FIgurE 2a: spectral reflectance curves for green 7. FIgurE 2b: spectral reflectance curves for Violet 23. www.flexography.org april 2011 FLeXO 47 At Harper Corporation we do more than sell anilox rolls. We deliver confidence that comes with a 100% performance guarantee, backed by a team of graphic experts, and supported by a full compliment of products and accessories. With anilox roll manufacturing and restoration facilities in Charlotte, NC; Green Bay, WI; Herford Germany and Bangkok, Thailand; Harper Corporation delivers dependable consistency no matter where you print. Harper Anilox Roll with built-in support. Performance guaranteed. From four locations across the globe. To learn more, call 704.588.3371 or Toll Free at 800.438.3111 Or visit our website. Anilox Roll Division HARPERi MAGE.Co M Americas • Europe • Asia ©2011