When considering the notion of achieving the best match between proof and press, there have been myriad approaches over the years. Before color management came into its own, either the press was adjusted to match the proof, or the proofing system was adjusted to match the press. Both approaches had their drawbacks, mainly in that both systems had limitations on how much they could be adjusted. Additionally, since printing presses all print differently (natively), that alone created chaos in the overall color reproduction system.
Once proofing technologies advanced and color management systems matured, it allowed for proofs to approximate the color output of a press very closely. Customers could finally have faith that what they saw in the contract color proof was what they could expect off the press. But what enables that approach to work is the notion that the press is the "stake in the ground," meaning that it should be viewed as the target, not only for the proofing system, but for the repeatability of the printing process as well. Remember: you can only have one target, just like in horseshoes.
But how does this work when you need to consider multiple presses, be it within one plant, across multiple plants, across multiple print providers, and/or even across multiple printing technologies? Well, for conventional print technologies (offset, flexo, gravure, etc.), you must modify the behavior of each press to target one condition. And these days, the best approach that addresses that is G7, which is both a methodology for calibrating presses to one condition and defining that very condition.
The color of the inks is specified via ISO 12647-2, and various metrics are defined to achieve a shared visual appearance across the various presses. Then, for digital presses, color management is utilized to target (via ICC profiles) either a custom-defined condition (after G7 calibration) or an industry-defined Characterized Reference Printing Condition. Both are based on the press, substrate, and ink system, and serve as the “stake" for not only proofing systems, but all presses to target. So, whether for a first-time proof or print, or a repeat proof or print, it doesn’t matter — the target is always the same. Then, process control targets and tolerances, based on that defined stake in the ground, serve as the way to ensure predictability and repeatability for future jobs and runs.
Keeping this mindset that the press is always the stake in the ground is what will keep your processes and your expectations all targeted at the same thing, thereby minimizing surprises and chaos with reproducing color.
PRINTING United Alliance and its Idealliance division provide color management and G7 standards trainings and certifications. Find an upcoming training by visiting printing.org/events/workshops.
As PRINTING United Alliance’s VP, Technical Services, Bill Pope leads educational initiatives, including the Continuous Improvement Conference and Technical Association of the Graphic Arts, while overseeing the Alliance’s consulting services and awards programs, and working closely with the newly merged team at Idealliance. With 30-plus years in printing and packaging, Pope frequently presents at industry conferences and events, and has authored numerous technical papers and articles for various journals and publications.