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FLEXO Magazine : September 2013
ogy, coupled with a lower volume anilox spec, can match this spec and deliver significant ink savings. Q: With new plate technology and surface screening, we are seeing significant solid ink density (SID) increases that are comparable to “Next Generation” plates. The gamut increase is apparently due to SID increase, so is it a realistic expecta- tion that the gamut increase is achievable with plate technol- ogy other than “Next Generation” plates? A: The fundamentals for increased gamut are three-fold. What we know from the conditions we captured were the conventional plate delivered a reduced density and a larger minimum dot. It was also apparent that the ink trapping was not as efficient as the next generation. We can only speak for our experiment and our findings. Q: If SID were run at comparable numbers, what would the comparison look like? A: The Next Generation would have a larger color space due to the smaller minimum dot, extended tonal range and better ink trapping. Q: If we increase density of CMYK, will we change the FIRST standard for density? How does an increased density of CMYK affect grey balance? A: Next Generation plate technology provides the printer with two options: increased color gamut due, in part, to higher achievable densities, or the capability to maintain established target densities (like FIRST) with higher line, lower volume anilox rolls leading to expanded cost efficiencies. Gray bal- ance can be maintained at higher print densities as long as the colors remain balanced. Q: If the increased color gamut with the Next Generation plates is due to increased density, couldn’t we just increase our density with conventional plates and get the same re- sults? A: The increase of color gamut happens for three reasons, an increase of density, expanded tonal range capability and better ink trapping. Stability and repeatability from the print- ing plate also play a role. The challenge with increasing the optical density with a conventional plate is that by doing so affects dot gain, especially the minimum dot. So in effect all that happens is the color space moves to a more dense range of colors. This poses a bigger challenge to then print halftone images and fading off to zero percent vignettes. With Next Generation plates these challenges are reduced significantly. Ann MichAud Q: Do you offer a crosshatch for your mounting tape? If so, does it come with different densities? A: Yes, 3M offers mounting tapes with microchannels in the adhesives. The microchannels will allow easy mounting with virtually no air entrapment. The mi- crochannels or crosshatch adhesives are available on all eight foam densities. Q: Why was a 900 lpi/3.5 bcm anilox used? Typical 900 lpi will have 1.9 -2 .3 bcm. A: We selected our anilox to represent a typical line for 150 lpi combination printing. Our Design of Experiment was conducted on two print stations running simultaneously; we needed two identical anilox rolls. Our selection of bcm was determined by the inventory of anilox rolls at the test location to most closely meet our objectives. Q: Why do the hardness of the tape and the hardness of the plate inversely affect ink density? Why does a hard tape increase dot gain, but a hard plate decrease dot gain? A: This is often confusing at first. Since the plate material is non-compressible, the softer the plate, the more it will conform to the substrate, increasing ink density and dot gain. Moving to a harder plate will decrease the conformability to the substrate, decreasing ink density and decreasing dot gain. The mounting tape, however, is a compressible mate- rial. A softer mounting tape will compress more, decreasing the pressure between the plate and substrate, thus decreas- ing ink density and dot gain. As the firmness of the mounting tape increases, the tape will compress less and the result will be increased pressure between the plate and substrate, increasing ink density and increasing dot gain. Michaud 20 FLEXO septeMber 2013 www.flexography.org