Color: It’s All in the Process

Many things make a package effective: size, shape, functionality—and color consistency. In packaging, an essential part of color management is to show what a brand color will look like on press. For package printers and converters, this involves the ability to reproduce color accurately, regardless of inks, coatings, substrates, blankets, plates, or process. The higher the value of the brand asset, the more critical the color. However, because the color spaces of printing presses vary according to ink, inking sequences, and paper grade, consistent color printing is difficult without reliable color management from the time a file enters the workflow until it is reproduced on press. This is the difference between a color-managed file and a color-managed workflow.

The need for faster makeready, on-time delivery, and reductions in cost and waste places a premium on predictable results and comparable quality, independent of location, substrate, or printing process. However, because it is now possible—and often necessary—to print the same brand colors on everything from paper and plastic to corrugated and shrink-wrap film, the level of technical expertise needed to produce consistent, saleable results from press to press, process to process, and job to job is considerable. Design specifications also may leave printers struggling with color that is difficult to reproduce on presses. When it comes to color, proof, plate, and print must deliver identical results. More specifically, this means that the proof must simulate as closely as possible the color from the press and hence, the product, as it will appear on the shelf in all its irresistible, eye-catching glory.

Recipe for repeatability

Once a job enters the workflow, multiple factors influence color. These include dot gain based on a new range of inks, printing substrates, and blankets, as well as the type and trapping performance of the printing plate. According to Marc Welch, U.S. channel manager, GMG Americas, a color-managed workflow has three components: repeatability in the pressroom regardless of printing process; prepress process control; and color management technology. “A repeatable pressroom is the foundation of process predictability whether the process is offset, flexography, or gravure,” Welch says. “The disciplines of repeatability include standard ink densities, standard press settings, defined blanket packing, ink quality control, and standard operating procedures.”

Platemaking also needs to be consistent. “Plate exposures, proper plate processor cleaning and maintenance, and quality control tracking of the prepress process are vital,” says Welch, adding that once the pressroom and the prepress are operating in a repeatable process, it is possible to integrate the “fingerprint” of the printing press into the prepress stage and to calibrate and manage the proofing technology to assure repeatability of the results. With careful attention to these three areas, Welch says, the ability to achieve a reliable proof to press match is available to any package printing company, regardless of size or printing method.

GMG’s ColorServer solution provides automatic color space conversions scaling, sharpening, separation, and optimization of pixel and PDF image data. The software reportedly permits the conversion of one CMYK color space to another while keeping the integrity of the black channel, meaning that offset data can be automatically converted to gravure data. The major advantages of GMG ColorServer are said to derive from the acceleration and automation of work processes by very accurate, high-speed color transformations that produce significant cost savings.

Color management is a tall order in itself, incorporating RGB to CMYK conversion, extended ink gamut sets, ink selection, and dot gain on press, “to name just a few,” says Tyler Harrell, solutions and innovations manager for Esko-Graphics. “The priority for any printer [is] to be able to create a predictable proof-of-press performance. Given that, a printer should never try to provide a press sheet to represent the best that can be done. It has to be representative of production. That’s the only way you can link a proof back to press predictability.”

Spot on

Where packaging workflows differ from commercial printing workflows is in the use of spot colors. “Spot colors play a huge part in any package design,” Harrell says. “The challenge is to determine how to recreate it on a proof. Many major packaged goods companies have people who do nothing but visit printers to make sure their brand colors live up to the ‘delta e’ deviations on press.”

Extended gamut proofs make the accurate representation of spot colors even more critical, although the development of more capable inkjet printers is rapidly closing the gap between what you see and what you get. “Some high-end devices have six or seven inkjet heads, providing a wider gamut,” Harrell says, adding, “While we’re not at the point yet where proofs can comfortably assure a color on press, but what a major development that would be if brand people did not have to attend another press run.”

A rising challenge is the increasing use by some printing companies of proprietary ink sets that cannot be adopted by many proofing systems—although the converter still must find a way to represent those colors in a proof. The challenge here, reports Harrell, “is to create a good separation of a photo using replacement inks.” Kaleidoscope, the device-independent color engine in all Esko-Graphics’ Scope workflow environments, performs color-matching operations within Esko’s FlexRip and creates ICC profiles for image retouching. As a centralized color management system, however, Kaleidoscope also goes beyond ICC profiling by enabling its color tools to be used in any combination of process and special inks, including multi-color process and other non-CMYK color sets like opaque and metallic. Kaleidoscope is fully integrated with Esko-Graphics’ IntelliCurve, FlexRip’s dot gain control engine. Esko-Graphics’ InkWizard converts jobs to any target color space, using Esko PackEdge as a host application. Off-the-shelf color sets (e.g., Pantone Hexachrome, Opaltone, FM6) and custom color sets are supported.

Sun Chemical agrees that color-matching and on-press process controls are the basis of quality spot-color print results. To reduce the incidence of subtle variations of the same brand color “that are undetectable until they wind up side-by-side on a shelf,” explains Iain Pike, business leader, brand color management, Sun Chemical currently is working with converters and their brand-owner customers on a “palette rationalization process” that aims to reduce the number of brand color versions to a manageable level. “A typical implementation may consolidate some 250 variations of brand colors down to just 24 target colors, making the overall workflow more manageable and assuring better color consistency,” Pike says. To set realistic targets and expectations as to what can be achieved on press, Sun also recommends that brand colors should be documented as physical color standards that take into account printing process, ink systems, and substrates and are produced under controlled conditions for color consistency. “Other package end-use requirements that affect color, such as light-fastness and chemical resistance, etc. also should be reflected in the physical color standard,” Pike says. pP