Coudray discusses the influences that ink values, software, and other variables have on the creation of effective simulated-process separations.
It’s not my intention to analyze the various techniques, but rather to focus on what happens after the seps are delivered and the job is on press. Press operators resort to all kinds of gyrations to try and find a way of making underperforming separations work. Typical manipulations include changing print order, mesh count, ink colors, squeegee durometer, pressure, angle, hit sequence, and print speed. This time-consuming, hit-or-miss approach mostly yields mediocre results—or worse, the job is pulled and sent back to the art department for new seps, screens, and round two on press. It’s a frustrating and expensive waste of time.
There are two primary approaches to simulated-process separation. The first involves the premise that ink colors are opaque and will not optically mix, but instead rely on physical ink mixing to form secondary or tertiary colors. This approach tends to be very forgiving on press as there is no requirement to control pressure and only limited requirement for control of dot gain. The only gradation that occurs comes from the physical mixing of the ink dots. The dots often completely disappear, which gives the impression of near-continuous tone and makes it considerably easier to get good—and even outstanding—results under almost any printing condition.
The trade-off in this case is that you need as many printheads as you can get your hands on. It’s rare for this type of separation to work with fewer than ten colors, and most outstanding work is accomplished with 13-16 colors. The opaque version of simulated process is little more than a modified posterization, where tonal transitions are softened with some halftone blending. Close examination of the final print almost always reveals some obvious tonal banding and issues with holding fine detail.
The second type of nChannel separation is more complicated. It’s based on the assumption that inks do mix both optically and physically to deliver a much broader range of tone and color. With this approach it’s possible to deliver incredible detail, tone, and color. The color gamut is much, much greater than any CMYK gamut, and is typically accomplished with fewer than eight colors.
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