G7 certification for the packaging industry is the ticket for a brand’s print buyer to ensure consistency across variables and offers other benefits, writes Danielle Jerschefske
Hammer Packaging in Rochester, New York, is one of the first packaging printers in North America to achieve G7 Master Printer Status, a qualification granted by IDEAlliance, a non-profit industry association which disseminates best practice methodologies, specifications and standards for the print industry.
When it comes to print consistency across a brand-marketing portfolio, print buyers have traditionally found it difficult to match color across different regions or across different print types and materials. For the packaging industry, G7 represents a radically different approach to this problem.
Because Hammer produces printed labels and package decorations for the global beverage, food, horticulture and household products industries, including cut & stack, in-mold, shrink sleeve, roll-fed and pressure sensitive labels, it was eager to reap the benefits found in the G7 methodology.
Essentially G7, or Near-Neutral Calibration, defines targets that allow packaging printers to match a proof to a press; a press to a press; one process to another; and across various consumables. The ‘G’ stands for gray as in gray balance or neutrality, and the ‘7’ refers to the seven major process printing colors.
G7 uses colorimetry to specify both the color of the media, in white point, and the color of the inks in accordance with ISO 12647-2, which describes gray balance as 50/40/40 CMY. The resulting grayscale and tonal curve is used for calibrating a proofing and/or printing system. G7 utilizes the new ISO 10128 standard to set near-neutral calibration.
Rather than changing the tint by diluting color with white or black ink, a grayscale-based system adjusts the tone, where the eye is more sensitive than saturated color. All a G7 certified converter like Hammer has to do is maintain gray balance and tone within this set range.
Benefits to brand and converter
Lou Iovoli, Hammer’s VP strategic partnerships and marketing, says, ‘The advantage to the brand owner is that we can provide our press 'condition' to a given designer so they can provide customers with a proof that will match the final print image from our press. In this way our customers will know sooner what a design will look like, rather than having to wait or travel for a press approval.’
Hammer started using the G7 process to control both press and proofing in Fall 2010. Iovoli says, 'With this process we are able to map the wide gamut of colors used in packaging and produce a proof that represents the press condition. This process takes into consideration the various combinations of substrate and inking in either surface or reverse printing. We strive to reduce the uncertainty of the proof matching the printed sample, allowing us to deliver high quality products for our customers.'
A second benefit is that the print file no longer needs to be modified or adjusted to print to any of Hammer's presses regardless of the printing process or consumables used. This can mean significant cost savings since one file can be used for everything: cartons, labels, a webpage, POP and flexible packaging.
If all the print products have the same gray balance and neutral tonality defined by G7, they will all look remarkably alike to the human eye. Since buyers believe the similarity of the visual appearance across print products is critical, and are gaining a better understanding of the G7 method, many have started to make G7 a buying requirement.
Lastly, G7 calibration gives print buyers flexibility in processes and materials used in the packaging industry. It streamlines the coordination between the pre-press house and printer thereby improving speed to market.
G7 defines the print condition in two ways – tone reproduction, gray scale – and it describes how to use the principles of digital imaging, spectrophotometry, and computer-to-plate (CtP) technologies to achieve color matches using quality inks and papers. Its Neutral Print Density Curve (NPDC) defines the neutral density of the grayscale curve with a combined CMY curve of 50/40/40 at the middle tone and specifies the tone from highlight to shadow, taking priority over traditional TVI curves. The calibration method calculates corrected RIP values that will force the press to replicate the desired NPDC curve based on the given press conditions.
As the NPDC curve approaches the solids then the lines will deviate. Gray process control patches should always be printed on the production runs in order to regularly verify gray balance. It is important to remember that gray balance tells the printer that the color has changed, not what is supposed to change. It cannot compensate for ink and substrate variances.
Flexography has come a long way through process improvements and advanced technology to better allow print to hit G7 requirements. This is important as the market is seeing increased demand by brand owners to match offset printed products to flexographic printed products on the store shelf. The steps to achieve G7 calibration are as follows:
• Ensure inks hold to ISO standards
• Print a P2P (Press to Proof) to target conditions
• Evaluate print samples to match 50, 40, 40 CMY (as defined by ISO)
• Generate plate output curves to NPDC
• Print another P2P and production run to verify print conditions
The key challenges to keep in mind are matching inks with ISO standards, and handling substrate variation. As all materials vary there will be different white points, and inkjet proofers will need to effectively simulate correct colors over the variety of media options. Also, Hammer has found issues in matching gray balance in offset print to HP Indigo output.
Iovoli says, ‘Now this is something of a closed-loop proofing system. It’s very exciting to have color verification on press for acute definitions which brands like Coca-Cola demand. This greatly benefits us in cost of pre-press and in the consistency we’re able to provide our clients.
‘Right now we do not have all of our customers on board and we’re limited to utilizing G7 to new work because we have to have the file designed to meet our press conditions. Nonetheless, we are optimistic about the system and the benefits we’ll find moving forward.’
Hammer has tasked three associates to achieve and maintain G7 certification – one pre-press, flexo and offset professional. The converter has invested in a new Epson X900 series proofing system with on-board X-rite spectrophotometer to achieve more accurate measurement and certification of proofs. Never one to rest on its achievements, Hammer’s next step is to move into ‘G7 Extreme’ by applying the G7 gray balance methodology to expanded gamut printing incorporating the colors orange, green and violet (OGV).
G7 is truly a revolutionary method to meet print buyer requirements and offers assurance that the final color quality of the printed media is true to the creative intention, and is delivered at a competitive cost. As the trend for shorter-runs and frequent design changeovers continues across package printing, the industry can expect to see a shift towards this grayscale process of achieving consistent visual color matching.
Pictured: G7 Neutral Print Density Curve
This article was published in L&L issue 3, 2012