Elusive "Perfect Proof"
The digital-versus-analog debate continues.
By Terri McConnell
Terri,
I read your column last month about [color management] and was wondering if you were going to highlight the difficulties we have with digital proofing in the packaging industry. These "difficulties" specifically pertain to spot colors and the use of modified process. With flexo, gravure, and limited offset packaging, we still have a hard time finding a quality digital proofing device that can reproduce good color when mixing the spot colors together with four-color process... . The world of digital proofing would be so much better if there were products [and] materials [available now] to help accomplish all packaging needs... .
Jim Koukol, Account Executive
Schawk Graphics
Jim is absolutely right—the area of digital proofing is a distinctive technology gap in an industry that has otherwise forged ahead with electronic innovation. To date, analog (or film-based) proofing is still the only method available for accurately representing both four-color process and the wide range of special inks, or spot colors, used in folding carton, flexible packaging, label, and corrugated printing production.
It appears we are in a "compromise" situation. While we continue to rely on film-based systems for contractual approval, we cannot fully utilize the array of color controls available to us in the digital world. On the other hand, if we choose to take the leap into an entirely digital realm, we must create workarounds for devices that are fundamentally unable to reproduce the entire package printing color gamut.
Says Gregg Tashker, global packaging segment manager for DuPont Color Proofing, "There is no single perfect proofing solution for the wide range of printed results we see across the packaging arena." Tashker explains that's why DuPont, one of our industry's leading suppliers, continues to work on enhancing current analog proofing technology, while simultaneously developing new digital solutions.
Indeed our analog options are more attractive than ever. DuPont claims its newest offering, the WaterProof CV (Color Versatility), can represent any Pantone™ spot color, including a full complement of metallic shades and fluorescent inks, with great precision. Also, it offers the ability to transfer the proofed image onto any substrate for 3-D prototyping.
The CV system uses a supplemental set of 16 call-out colors which are blended at a stand-alone coating unit and applied to a WaterProof transfer sheet. The sheet is then sandwiched with the film separation and exposed under UV light. After washout, the sheet can be laminated to a carrier substrate, like a TV dinner carton stock or a polypropylene diaper bag. A separate sheet is subsequently applied for each printing ink being used in the job.
According to John Awahmukalah, DuPont's North American product manager for packaging proofing, there are around 2,000 WaterProof systems in the United States, 60 percent of which are installed in commercial printing plants. "For the past year and a half, we have seen an increasing number of CV's being purchased by packaging trade shops and converters," says Awahmukalah. "Most are being used in the folding carton and flexible packaging markets, where quality demands are very high, but we also see some in tag and label and corrugated applications."
While analog systems can accurately represent the spot colors inherent in packaging, the need for intermediate film separations makes them time- and cost- prohibitive for communicating color throughout earlier phases of the packaging production cycle, when many critical approval decisions are made. Certainly, they are a serious holdout in any computer-to-plate workflow, where eliminating film is a prime economic factor.
Though film-based proofs show color traps and the actual halftone dot structures that will be plated, they are not necessarily as predictive of final printed results as some digital proofs. For example, the effect of dot gain, especially in flexographic printing, is not as apparent on an analog proof as it might be on a digital proof that has been carefully profiled with actual press fingerprint data.
Digital developments,drawbacks
The packaging industry, just as commercial printing before us, is steadily moving towards totally digital workflows. Despite the drawbacks, we are currently employing dozens of different types of digital proofing systems. In terms of price/performance ratios, we can categorize those systems into three major product groups from the most to least expensive: digital halftone systems; continuous inkjet systems; and drop-on-demand inkjet systems.
Digital halftone systems use high-resolution lasers to image pre-coated, transferable color sheets. For example, the Spectrum devices from CreoScitex are capable of imaging Imation Matchprint, Kodak Approval, and DuPont Digital Halftone Proofing media. While these systems offer the most exacting digital image fidelity and true halftone reproduction, the number of spot colors that can be shown is still limited.
More affordable, continuous inkjet systems like the IRIS, Imation 4700, and Digital WaterProof do not render actual halftone dots, and must simulate spot color from a palette of only yellow, magenta, cyan, and black inks. On the plus side, however, these systems can offer a complete set of digital prepress color management tools. The Digital Waterproof system, for instance, boasts support for inbound and outbound ICC profiling, SWOP certification, and Pantone Hexachrome certification.
Features like those allow the Digital WaterProof system to be characterized (within the limits of its color gamut) to simulate many printing and proofing processes. Additionally, the device can be calibrated (to varying degrees of accuracy) to ensure consis- tency from proof-to-proof and from device-to-device—a must for multi-plant color communication.
At the lowest end of the market are the drop-on-demand (DOD) inkjet systems, such as the Hewlett Packard, Canon, and Epson desktop engines. Product Manager John Malloy says DuPont has entered into an exclusive agreement with Epson to take this low-cost, very accessible technology out of the "pleasing color" market and into more serious applications.
DuPont has coupled the Epson Stylus Pro 5000 and the wide-format 9000 printers with a Windows NT-based Color Station. The Color Station software RIP supports a wide variety of file formats and controls a number of important proofing functions such as spot color and paper simulations, color correction, color bars, and job tickets. In addition, DuPont offers a line of specially matched inks and media that extend the color reproduction gamut of the Epson device. For around $5,000, low-cost "desktop" devices can become suitable, color-controlled proofers for communicating color earlier in the production process.
Working knowledge of color theory and hands-on experience with color measurement and management are keys to successful digital proofing—regardless of how sophisticated the system is. Perhaps DRUPA will offer us new solutions, but until there is a digital system that specifically addresses all the nuances of packaging production proofing, we will continue to push the limits of available technology. Sorry, Jim.
