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FLEXO Magazine : September 2014
Efficacy Of UV & LED UV Curing 2013 Rossini Research Scholarship Winners Share Details of Study Natalee Consulo, Lena Haidar, Mark MacManus [Editor’s Note: Part 1 of this study, published in last month’s FLEXO® , of- fered an overview of UV, mercury and LED curing, key lamp differences, the project’s research method and some of its results.] T he purpose of this study was to provide accurate detailed data related to the print- ability differences between conventional UV flexographic printing and LED UV flexographic printing. TONAL VALUE INCREASE Tonal value increase, often referred to as dot gain, measures the actual yield of dot sizes once printed compared to the dot size in the file. The tonal value increase was measured using a X-Rite 530 model spectro- densitometer. Fifteen samples were randomly selected from each run. Cyan, magenta, yellow and black values were measured at 2 percent, 10 percent, 30 percent, 70 percent and 100 percent densities. With conventional ink, paper fibers normally absorb the ink more readily, while film has greater ink holdout, meaning that the ink remains on the surface of the substrate. UV inks behave differently on the surface of the substrates, due to their curing speed. The curing process polymerizes the ink on the substrate and the speed of the curing process does not allow the ink to spread out as much as it normally would with conventional ink. The data in Graph Set 1 and Graph Set 2 provides the specifications for the pressruns on paper and film, respectively: The graphs in Graph Set 1 display the TVI for all film samples for each color. There is negligible difference in the TVI for all runs using SF 2.6M WH BOPP TC/S692N film. The graphs in Graph Set 2 display the TVI for all paper samples for each color. There are slight differences in the TVI, but the differences are negligible for TVI in runs using 60# Elite/C2500/40# paper. 66 FLEXO | SEPTEMBER 2014 FTA TODAY Lena Haidar (left) and Natalee Consulo, presenting the findings of their report at Forum 2014. PART 2 INA SERIES