Highlight gain is the dominant effect with Flexcel NX plates. Halftone dots as small as one or two pixels at 2400 dpi (0.4 or 0.8 percent at 150 lpi) can be imaged and printed reliably, but these small halftone dots are subject to compression dot gain, causing a small flexo discontinuity.
A typical flexographic press device condition using Flexcel NX plates at 175 lpi has the following behavior, demonstrating the effect and magnitude of the discontinuity:
- The color change from the substrate to a 1% magenta dot is 3.7 DeltaE—an easily noticeable difference. The 1% tint has a tonal response or EDA of 9%.
- The color change from the substrate to a 2% magenta dot is 4.5 DeltaE—less than twice that exhibited by the 1% dot—and the 2% tint has an EDA of 10%.
The color change from substrate to 1% is much larger than from 1% to 2%, while the typical offset color response has similar color changes from 0% to 1%, and 1% to 2%.
For Kodak Flexcel NX plates, it's recommended that you characterize the press with a built-in or custom NX transfer curve according to the cyan midtone (50% input tint) TVI. Use the default Mindot values, and don't increase the Minimum Tint Out value.