Color by the Numbers

A large printable surface area combined with a wide range of sizes, shapes, and decorating options make beverage cans the ideal packaging format to create brand presence on the shelf and in consumers’ hands. While creatively enticing, however, the proliferation of options for can decoration give rise to a tremendous number of opportunities for unwanted variation and distortion in the printing process, where consistent, repeatable color measurement is the key to color quality control.

Crown Beverage Packaging, a business unit of Crown Holdings, Inc., is a worldwide leader in metal packaging, with $8 billion in sales and more than 20,000 employees and 130+ plants worldwide. Headquartered in Philadelphia, Crown Beverage Packaging North America works with some of the largest consumer goods companies on the beverage side, including Pepsi, Anheuser-Busch, Dr. Pepper, Snapple, and many other private label brands. The company recently helped Molson Coors Canada streamline its printing process and enhance color consistency across different packaging facilities with the new SP64 spectrophotometric color measurement system from X-Rite. By asserting an automated color standard, color harmony now can be achieved across locations, thereby boosting the efficiency of the can printing operation and reducing both time-to-market and associated production costs.

Enhancing the brand experience

According to Marketing Manager Tom Hughes, Crown Beverage’s mission is straightforward, i.e., to help its customers build and strengthen their brands with the consumers they deal with every day. To accomplish this, the company focuses exclusively on beverage can design and production, working with the customer and the customer’s designated prepress house, and leaving cartons and labels to other suppliers.

The can printing process itself is unique. Unlike standard printing, which is 4-color process, wet on dry, there is no drying between the application of each color. The cylindrical can is sent through the press via air vacuum to a mandrill. The printing plate transfers each color onto multiple blankets, where they are registered wet-on-wet at speeds of up to 200 cans per minute. The complete image subsequently is wrapped around the cylindrical can and overvarnished with no drying time.

“A lot of it is generic industry process,” explained John Corelli, manager of graphics planning, customer and technical service North America. “The only area that is unique and somewhat proprietary is what we do internally to reduce variation on press.”
According to Corelli, the nature of the process gives rise to a certain amount of distortion in the printing—up to 25 percent ink gain on screen work. Referring to the need for ink curve adjustment, he said, “The desktop operator whose job is to perform the initial prepress separation has to understand how much to reduce a given screen to allow that gain in order to print as it should. You can’t go to press without making those adjustments.”

Having made the appropriate prepress adjustments, Crown still “pilots” its cans on a proofing press to refine the color blends, screen values, and overall contrast, then secures customer approval before commencing actual production. The reason for this, Corelli explained, is that for anything that features complexity and demands a clean image, “until you have the graphics on the can, you really don’t know how the inks or the gain will react. We want to ensure we’ve met the customer’s requirements to the visual color and print image, as well as build in all the necessary efficiencies for the production line.” To that end, Corelli added, Crown uses the exact same ink, varnish, and distortions to achieve the closest simulation possible of the actual, printed, cylindrical can.

Molson Coors initially approached Crown Beverage with a request to build a system that could define and identify color exactly, Corelli said. In response, Crown enlisted the help of X-Rite and its ink supplier, INX, to develop the complete process, beginning with the customer specifying its color measurement needs. The end result would be a proprietary database and measurement methodology exclusive to Molson Coors.

By the numbers

The X-Rite SP64 Portable Sphere Spectrophotometer from X-Rite enables Molson Coors Canada to assign specific numeric values to colors that are applied as standards across the company’s three production facilities. Previously, these colors had to be gauged by eye, subjecting them to variations in lighting and the challenges of measuring on a reflective can surface.

“It was all visual,” Corelli said. “Don’t get me wrong; we had good control and made good cans. Now, however, we’re better, faster, and more efficient on press, and we produce better quality because the system has built in accountability and enforces process rules at press side. The upshot is that we have better, more accurate control, and I can honestly say we’ve become a better quality supplier in color and print as a result.

Most important, Corelli said, the X-Rite system enables the press operator to understand what adjustments have to be made on press. For example, if the SP64 is reading on the light side, we know we need to apply more ink film weight, or, if it’s too dark, that we need to reduce the film weight of the ink. There are a lot of things the instrument readings will display that will alert the press operator and management to what adjustments need to be made.”

“Everyone follows a standard operating procedure,” Corelli said. “There’s a lot of recording and multiple procedures that have to be followed from the start to the finish and the last can comes off the line,” he continued. “When we establish the graphics and the color measurement for a given label, we set the standard at that plant. We must establish a firm standard before we can release the program to any other Crown manufacturing plant. From the initial run, with the customer present, we refine the color, print, and measurements to meet their requirements. Once the customer signs off, we run off many cans to make sure they match the approved measurements. At that point, we release the standard to all of the plants that may be running that can.”
Where the rubber meets the road

The X-Rite implementation truly takes effect on press during the initial production run, when the reading and final can standard are established, Corelli said. “We do this a good 20 minutes after we start production so we have real, true, commercial production value. There are a lot of things that happen as the press warms up; for example, the rolls start to expand, there’s more distortion, and we have to adjust a bunch of things and then we know that its commercial and it shouldn’t move after that.”
Ultimately, all information about an approved graphic—including customer name, design name, and engraving number—is uploaded to the X-Rite server Crown maintains at its corporate headquarters in Philadelphia. Subsequently, each graphic within the Crown system is identified by a number that can be plugged into any Crown system to retrieve all of the specifications and requirements for that job, including color measurements.

Crown has lavished significant attention on implementing the X-Rite system. Training extends from production personnel and plant management to corporate quality staff, and is ongoing to involve new hires and personnel who move from one position to another. It also includes an element of color theory and visual color testing to determine whether production personnel are capable of making fine color adjustments when needed, Corelli said. After all, “Once the instrument tells you something is ‘too blue’ you need to be able to make the fix.”