PrintAction - March 2009

Delta and the Deviations

Consultancy group IDEAlliance recently launched Gracol.com to differentiate its family link between the GRACoL proofing certification and G7. As Ide-alliance.org states, “Although G7 was developed by the efforts of the GRACoL Committee, it should not be confused with GRACoL.” G7 is a calibration process based on a target of neutral print densities, which serves as a control from where printers can build colour management. GRACoL, on the other hand, refers to a commercial offset look-and-feel, and is commonly applied to sheetfed presses, among other processes and in particular with inkjet proofing – General Requirements for Applications in Commercial Offset Lithography.

In late-February, the GRACoL certification of three HP Indigo press models – 7000, 5500 and 5000 – marks the first instance of a non-inkjet or a non-proofing system to be certified. Much of this technical achievement is orchestrated by CGS’

ORIS software, specifically its Press Matcher Pro application. The same software is currently being tested with a Xerox iGen4 in IPA’s annual proofing roundup – directed by Ryerson GCM chair Abhay Sharma.

“Our inks are the best thing going for us,” says Bobby Parker, describing one of the key factors for why HP achieved GRACoL before its rivals. While HP’s self-described liquid inks lie outside of the ISO specifications, which partly form the basis of GRACoL, Parker continues, “they are so close, and sometimes the reasons why they are not compliant is because they are outside of the colour… we are stronger than the specification.”

Beyond the L*a*b* advantages that GRACoL presents for electrophotography, toner-based machines also carry a self-calibration advantage over offset presses. “ GRACoL is colourmetric. It is taking into account print neutral density, but for G7 all they are concerned with is the density and the neutral curves – the starting point.”

Conversely, GRACoL focuses solely on the end result – a printer may or may not use G7 to get there.

The production marriage between electrophotography and offset is fostered by GRACoL-certified proofing on Indigo presses. “What if you under-run a job and you need to match that job on a digital press? What if you need to bail a customer out or maybe the job is not scheduled to run but he needs a few hundred for a tradeshow or something? Or a few thousand?” says Parker. “You have a device sitting in front of you that is very versatile.”

The GRACoL certification is based on using expensive CGS’ PearlDIGITAL 170 proofing paper, stuffed with materials like optical brighteners to better match offset stock, but Indigo proofing overall provides an economical matching system relative to inkjet. “If the media meets the GRACoL specification, the ISO standard, and the customer uses that media to calibrate his press, he will still achieve the results,” explains Parker, who initially will lead the HP team to implement its GRACoL system at customer sites – described as a 2-day process.

– Jon Robinson

GRACoL Certification Vitals

Four technologies are involved in the industry’s first electrophotographic GRACoL certification, which basis its results on a holistic proofing system, including: