Color Consistency: Using Ink Proofing to Overcome Challenges

Color, its importance and today’s need to accurately reproduce it on packaging cannot be overstated. The increase of brands in our market means colors must match perfectly in order to maintain buyer recognition and loyalty.

Simply put, the only way to accomplish this goal of color consistency is to focus on ink standards and ensure the package on the grocery store shelf matches the targeted color, regardless of the type of substrate. After all, it is the identity of the brand being represented on that package, so perfection is the only option.

Of course, we all know perfection isn’t always the only outcome. Challenges occur along the way that interfere with our goals. Because of this harsh reality, it is necessary to deepen our understanding of ink and how to achieve that ideal color.

Data courtesy of Pamarco

Behind the Ink

When focusing on the significance of hitting color targets on all substrate types, it helps to think about brands that have mastered the skill of consistently recognizable color. A global brand must have consistent color regardless of the manufacturing location, and packaging must be produced using the same formula and action steps. There must be accurate reproduction on a variety of substrates, on multiple types of equipment, run by a variety of people, using multiple different processes in all types of environments. With that kind of laundry list, how does anyone manage to get repeatable results?

Before we dive into the specifics of accurate reproduction, let’s begin in the shallow end with a quick review of the moving parts behind ink. The first priority is that ink must arrive press side ready to run. That means meeting L*a*b*, Delta E and density requirements. All ink manufacturers have quality control procedures that include ink proofing technology, allowing them to meet brand owner requirements for color. The printer receiving the ink also has proofing technology to ensure the correct color match on site. But what happens when ink proofing procedures are not followed or are not performed consistently?

When ink arriving press side isn’t the correct color, printers find themselves with density outside of the needed range. In other words, it becomes a problem detectable by the naked eye. Sometimes operators notice before it’s too late and are able to make adjustments. But press time is costly, so even minor changes can be an expensive undertaking. Waste of time, waste of substrate, waste of consumption—the list of possibilities is long, not to mention the customer relationship strain during a long press approval, and/or the rejection of the job entirely. Even just a few extra minutes of makeready time that is caused by ink issues can be very costly on an annual basis, especially when press time costs $600/$800/$1,000 an hour—that can quickly become an expensive proposition.

That’s apparent even if we do the math with conservative figures:

  • Four jobs per day
  • Five minutes saved per job
  • Press time: $800 per hour or $13.33 per minute
  • Annual savings: $97,000!

Achieving High Quality Color

Image 1

In order to avoid these issues and earn those annual savings, we need ink that is pleasing to the highly accurate instrument most of us innately possess: the naked human eye. For this reason, drawdowns to ensure quality have been a staple of ink manufacturers and in-house ink departments for years, but repeatability has been a struggle for just as long. The keys to achieving the highest-quality ink are three-fold: density, L*a*b* and Delta E standards. We all understand density, but what are the other two and why do they matter to drawdowns?

Delta E is a metric for understanding how the human eye perceives color difference. It is the measure of change in visual perception of two given colors. The term “delta” comes from mathematics, meaning change in a variable or function. The suffix “E” references the German word empfindung, which loosely translates to “sensation.”

Defining L*a*b* is a little harder. It is similar to geographic coordinates—longitude, latitude and altitude. The color values give us a way to locate and communicate colors where L is lightness, a is the red/green value, and b is the blue/yellow value, as shown in Image 1.

Image 2 provides us with a visual model of the way Delta E and L*a*b* intertwine.

Correlating Ink to Press

So, how do we apply this information to the pressroom? First, ink technicians need to have an anilox roller that correlates with the press configuration. A ceramic anilox roller, with or without doctor blades. Secondly: records, records, records! These are the most important factor in repeatability (hint: lab notebooks). To properly correlate ink to press, with the knowledge you collect, involves gathering the necessary samples and following these seven steps:

  1. Printed sample from press after approval
  2. Fresh, wet sample of ink from press
  3. Set up proofer using an anilox volume that is the same or similar volume as the press
  4. Produce a drawdown on the same substrate that is running on press
  5. Compare press sample to proofed sample
  6. Volumes should correlate 1:1. If not, make slight adjustments until you hit the perfect match for the ink color you are testing
  7. Once the color matches within at least 1 Delta E, record anilox roller specification and proofer settings (most converters are working at or below 2 Delta E)

As technology has increased, so has our ability to manage and measure ink properly. Printers expect the variables keeping them from increasing press-side productivity will be eliminated by technology advancements. Pamarco has been gathering ink proofing data for more than 10 years with the goal of reducing on-press ink adjustments in an effort to meet those expectations. Industry tools—like the company’s Iris (an automated precision proofer)—do just that, in a repeatable, consistent, automated manner, helping to reduce ink consumption and its associated cost, shorten press setup and mitigate color approval issues, and ensure you get the color you need every time. (Iris also works with current Pamarco hand proofers, so your old equipment isn’t becoming obsolete but updated instead.)

Further, these tools can allow an ink department to improve accuracy and speed while increasing press productivity by removing ink adjustment from the pressroom. With variable speed settings that equate to idle at 1 fpm to 300 fpm, the operator saves time. And with the ability to use doctor blade systems, there is enhanced calibration with production conditions. The value of ink proofing and this proofer device are readily applicable to the coating industry and specialty coatings systems as well as proofing for gravure. The options are limitless.

Image 2
Data courtesy of Pamarco

Running the Job

So we’ve walked through the importance of ink proofing and modern tools to assist—What now? You’ve started to run your production job. What’s critical? Being able to maintain the color that is in the bucket and being applied to the web or sheet, right? It needs to deliver the same ink qualities through the first 15 minutes that it does for the entire 24-hour pressrun—in the middle of winter or the hottest part of summer. Excessive variation in density not only affects color, but also increases ink consumption. Running a higher density than what is required to produce the job means that you may be consuming 3 percent to 5 percent more ink than necessary. With ink typically being the second-highest raw material cost to produce the job (after substrate), savings here can create real value.

At this point, there are two to three areas that need to be at the forefront of your attention: viscosity, pH and temperature—depending on whether your ink is water-based or solvent-based. By managing these three components, color can be maintained throughout the run to minimize waste and increase productivity with fewer defects.

About the Author

headshot John Rastetter
John Rastetter, as the vice president of sales and marketing for Pamarco’s Flexo division, is responsible for leading the Americas sales team and executing the strategies for sales in North America, Canada, Central, South and Latin America. With more than 30 years in the printing and packaging industries prior to joining Pamarco, John has held various executive positions at some of the leading suppliers to the printing industry, developing and managing sales and service organizations in North America, Asia Pacific and Europe.
headshot Jeff Ashburn
Jeff Ashburn is a 30-year veteran of the printing ink industry with a primary focus on paper and board packaging. Jeff currently serves as VP – Corrugated & Merchandise Bag Division for Flint Group Packaging Inks – North America. Throughout his career, Jeff has fulfilled a variety of roles in the commercial and technical facets of the ink industry.If you’d like to know more about how to gain or maintain control over viscosity, pH and temperature, look over the Total Flexographic Ink Management white paper.