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FLEXO Magazine : December 2012
when comparing job costs from cradle to grave - the total cost of converting. You will find that in multi-press shops, assigning jobs becomes more complex, as you must balance the avail- able equipment with the available experience of the opera- tors and support staff. The most successful ECG systems have reported utilizing dedicated presses, which are setup with 10 or more stations to handle the seven process inks plus any white ink, metallic inks and clear coatings. When choosing extended gamut primaries the following generalizations may be applied, based upon the field trials reported here. The first ink to be added should be an orange ink, preferably a slightly yellowish orange. Examples include Pigment Orange-34 and Pigment Orange-64 (average gamut increase 23 percent). The next primary color to add would be a green (average gamut increase 22 percent). In this study, it was assumed that a yellow-shade green would provide the largest gamut, but in fact, the more traditional bluish green of Pigment Green-7 outperformed both G-36 and blends of green and yellow pigments. Finally, the last color to add would be a very reddish blue or a bluish violet (average gamut increase 16 percent). There are not very many red-shade blue pigments available and some users have reported using a primary pro- duced by blending a violet or purple with a less reddish blue to achieve the hue that they desire. Blended or toned primaries have been successfully utilized in process printing, but it will be more difficult to maintain a stable color since the blended ink will have two sources of pigment-based variations. Based on the pressruns in this study, Both the mean and median increase in gamut, across all substrates, from a standard CMYK ink set to a CMYKOGV ink set is 60 percent. The general recommendations on hue are such that, the hue of the orange primary should be close to being comple- mentary, that is 180° opposite, to the cyan primary, the violet primary should be close to being complementary to the yel- low primary and the green primary should be close to being complementary to the magenta primary. From the results of this study the following can be recommended: • Magenta (PR57.1 or PR52) with metric hue angles be- tween 0° and 8°; • Yellow (PY14 or PY74) with metric hue angles between 93° and 98° • Cyan (PB15:3 or PB15:4) with metric hue angles between 230° and 240° • Orange (PO34 or PO64) with metric hue angles between 50° and 58° • Green (PG7) with a metric hue angle between 178° and 182° • Violet (PV23) with metric hue angle between 302° and 309° ACKNOWLEDGEMENTS The Committee wishes to thank the FTA and the staff for all of their support during this project. In particular, Mark Samworth, Esko, and Al Bowers, R.R., Donnelley, invested hundreds of hours preparing the artwork, reading the sup- plied prints and preparing the database of summary data. This paper reports only the very pinnacle of the mountain of work that they performed. We also thank all of the converters who were willing to share the printrun experiences with the committee and by way of this report with the entire member- ship of the FTA. n About the Author: Danny Rich is senior color physicist, Sun Chemical Corp. He is based in Carlstadt, NJ. REfERENCES 1. K. Guyler, “ Visualization of Expanded Printing Gamuts Using 3-Dimensional Convex Hulls,” TAGA Proceedings, pp696-707, (2000). 2. Hexachrome is a trademark of Pantone LLC, World Headquarters, 590 Commerce Blvd., Carlstadt, NJ 07072-3098 3. J A Stephen Viggiano and William J Hoagland, “Colorant Selection for Six-Color Lithographic Printing,” Proceedings of the Sixth Color Imaging Confer- ence: Color Science, Systems and Applications, IS&T / SID, pp 112 - 115 (1998). 4. M . Y. Cartons B.V., Kooiweg 12, NL-4631 SZ Hoogerheide, Netherlands 5. Opaltone Opaltone Australasia Pty. Ltd., Suite 2, 7 Hinde St, Ashmore QLD 4215 Australia 6. K. Zeleznik and J. Sperry, “Standardized Data Sets for Expanded Color Gamut”, Artisan - Clemson University, presented at TAGA Conference 2011, Pitts- burgh, PA, March 6-9, 2011. 7. FIRST 4.0 is the publication of the Flexographic Technical Association that contains the Flexographic Image Reproduction Specifications and Tolerances. It is available from the FTA, 3920 Veteran’s Memorial Highway, Suite 9, Bohemia, NY 11716. 8. Color Engine Pilot is a product and trademark of Esko, Kortrijksesteenweg 1095 BE-9051 Gent Belgium, and was on loan to Clemson University for this test. 9. CGATS - the Committee for Graphic Arts Technology Standards, the ANSI accredited body for developing standards in the graphic arts, has developed a series of standard test images for ANSI Committee Imaging Technology known as IT8/7 and 7.4 is a large array target for 4-color process printing. This target is available as an image and it associated color data from the NPES The Association for Suppliers of Printing, Publishing and Converting Technolo- gies, 1899 Preston White Drive, Reston, Virginia 20191. 10. GRACoL is the publication of IDEAlliance that contains the General Requirements and Applications for Commercial Offset Lithography. It is available from IDEAlliance, 1421 Prince St., Suite 230, Alexandria, VA 22314-2805. 11. ANSI / CGATS Recommended Industry Practice, Color characterization dataset development – Press run guidelines, NPES The Association for Suppliers of Printing, Publishing and Converting Technologies, 1899 Preston White Drive, Reston, Virginia 20191 12. XRGA is a trademark of the X-Rite Corporation and stands for X-Rite Graphic Arts scale of color measurement. It is a process for obtaining consistent instrumental readings from the full range of instruments used to characterize the color of print. EyeOne and EyeOne-IO and EyeOne-iSIS are products and registered trademarks of the X-Rite Corporation, 4300 44th Street Southeast Grand Rapids, MI 49512 13. ANSI / CGATS Recommended Industry Practice, Color characterization dataset development - Procedures for color measurement system process control and for inter-lab coordination, NPES The Association for Suppliers of Printing, Publishing and Converting Technologies, 1899 Preston White Drive, Reston, Virginia 20191 14. Excel® is a product and trademark of the Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 20 FLEXO december 2012 www.flexography.org 2013 media kit