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FLEXO Magazine : September 2009
34 FLEXO SEPTEMBER 2009 www.flexography.org PLANTS & PROCESSES Measuring color and dot gain ensures a controllable process. Photo courtesy Smyth Companies. Keeping it in Balance Measuring During a Run Helps Smyth Keep Color in Control By Kim Madigan We here at Smyth have been running to the numbers for the past five and one-half years. What does running to the numbers mean? It means that, during a pressrun, all process colors are printed with a specific anilox roll, a prov- en impression and to targeted densities and dot area numbers. All of the numbers are recorded throughout the run. During the fingerprinting process, we capture a picture of our press using a specific set of anilox rolls, inks, press set up, stock and plates. This press fingerprint helps us balance the numbers in prepress (they are the keeper of the curves). The balancing of curves is what gives us our gray balance. When a production job using this fingerprint information hits press we have already established the density numbers, the starting dot area and the balance tolerance we are look- ing for. Once the press operator has the press set up and run- ning to the original density, and dot area numbers as called out he/she documents the starting point for the run. During the run, the operator pulls additional print targets from press, reads them and documents the numbers. The documented numbers give him/her a log of information on the run. The operator is able to catch one color that begins to spike and retune. Keeping close control of the dot area bal- ance is key to gray balance and good color. The operator is able to watch over a long run for plate wear or dot area gain that can no longer be retuned and request a new plate in a timely manner, incurring limited time down on press because he/she could predict the needs of the press. We have been able to establish a consistent process, docu- mentation to support the process and acceptable tolerances. We document throughout a run, review the numbers to look at training and equipment needs and concerns with stocks and constructions. Throughout our process, documentation proves that our process is under control. THE FIRST EXAMPLE When Smyth was offered the opportunity to run the FIRST 4.0 front cover, the staff was very excited. We had a planning meeting to discuss the logistics---press, plate material, stock and timing. Once we had determined our direction, we were on to the fingerprinting process. The press was set up with our standard process anilox rolls, and "proved" impression. Then we saved samples and data from the run for analyzing later. The curves were then built, final files created and plates made following our standard process. When the final job was on press, the operator just ran up to the documented densi- ties and the balanced dot areas with very little adjustment. The print outcome was, as expected, vibrant and rich. If we had skipped this fingerprint step and guessed at the char- acteristics of this tag stock on our new press we would have been chasing color. ABOUT THE AUTHOR: Kim Madigan has a Bachelors of Science degree in Art from University of Wisconsin-River Falls. She is a 20+ year veteran of the printing industry, is the director of corporate color for Smyth Companies Inc. Her responsibilities include developing processes to support color management in all plants, including flexography and litho sheetfed. She is also an active member of the Twin Cities Flexo Association. • Fingerprinting process captures a picture of the press using a specific set of anilox rolls, inks, press set up, stock and plates. • Operator reads print targets during the run and documents the numbers. • Keeping close control of the dot area balance is key to gray balance and good color. PS&QS