‘Nu’ From Phototype

Despite the many advantages it brings to package printing, flexography has traditionally suffered from significant quality challenges, due to the way the ink is applied to the substrate. NuDot, a proprietary flexographic screening technology from Cincinnati-based Phototype, is designed to eliminate printing problems arising from dot gain and uneven ink lay by improving the way ink is transferred from plate to substrate.

Before NuDot, says Socrates Rettos, NuDot product manager, “A single plate could print a good solid or a good highlight, but it couldn’t do both.”

NuDot’s primary challenge, therefore, was to achieve optimum solid densities and deliver excellent reproduction of shadow tones without over-impressing the highlight range. This is a tall order by conventional “round dot” screening standards, where ink is squeezed out from under the dot, producing irregular, doughnut-shaped dots prone to dot gain and mottling. “A regular flexo plate on a plastic substrate is like an Indy tire in the rain,” says Gary Russell, VP of research & development. In contrast, NuDot’s uniquely shaped “shorelines” relieve that hydraulic pressure and ensure that ink is retained within the structure of the dot, yielding well-formed, printed dots, smoother ink lay and better image reproduction.

NuDot created its original technology, GR3, to improve printing on high-holdout substrates where hydraulic pressure builds up between the plate and substrate, giving rise to dot gain, mottle, and poor ink lay. “We were the ones who proved this technology was viable,” says Gary Russell, NuDot product manager. The premise is disarmingly simple. Asserts Russell, “If you can control dot gain, you can help control variability.”

There are a number of screening technologies on the market, but nothing currently available affects the entire tonal range the way NuDot does, say Russell and Rettos. “NuDot is the only proven product that relieves dot gain and helps the printer achieve a smooth transition and good ink lay across the tonal range,” Rettos adds. Moreover, incidental benefits usually include shortened makeready and faster press speeds.

Recent enhancements to NuDot are designed to expand substrate category and improve press latitude. These include NuDot Radial 8b for printing on films using high line screen and low-volume anilox rolls, and NuDot PB4 for printing on folding carton stock, such as clay-coated newsback.