Good, Better & Best Approaches to Achieving Color Accuracy

Press-side and inline color quality solutions designed for flexographic and packaging environments can slash makeready times, increase color accuracy and consistency—plus, put money back in the printers’ pocket.

Let’s face it, packaging printers have been getting squeezed by consumer package goods companies (CPGCs):

• Over the years, CPGCs have increased their variety of SKUs, which has resulted in overall shorter printruns
• More troubling, CPGCs have become increasingly critical of the color accuracy and color consistency of their printed brand colors and packaging artwork
• As a result, many CPGCs are demanding and specifying tighter color metrics and tolerances and, in many cases, are asking for color measurement data from their print suppliers to demonstrate the color accuracy and adherence to specifications
• In the end, this dynamic translates to increased waste and lower profit margins for packaging printers who now incur an increased number of makereadies, to accommodate the increased variety of SKUs that dictate longer makereadies to ensure the tighter tolerances are achieved
• The situation is further compounded by the new, younger generation of press operators that is being hired in pressrooms to replace more experienced and retirement-bound counterparts
• Finally, while handheld densitometers have been adopted in many pressrooms, these devices do not actually measure color and are incapable of reporting a color’s CIE Lab value. Also, they do not measure and report color differences using Delta Es. The best these devices can do is to measure and report the densities (ink film thicknesses) of solid color patches and the tone value increase (TVI) of halftone dot areas. While these are both very important print metrics and can absolutely be used to establish some level of process control in the pressroom, brand customers have begun to specify color accuracy using CIE Lab values and acceptable tolerances using Delta E metrics. Therefore, press operators armed with only densitometers cannot know if brand color specifications have been achieved or exactly what color precise changes are necessary to get within the specification

In these situations, operators must still rely on their eyes both during makeready to match colors and during the production run to ensure consistency. The danger here is long makeready times, color that does not hit the specification, and inconsistent color throughout the run, which can all lead to customer rejections, job remakes, increased waste and, ultimately, lower profitability for the printer.

So, what can a printer do to reclaim profitability? Well, the answer is no different than how printers have increased their productivity and profitability in other parts of their workflow over the last few decades. Simply put, package printers must adopt newer tools that employ the use of science and technology to remove the color “guesswork” for press operators to ensure a much more predictable, accurate and repeatable print manufacturing process.
Here is a look at the “good,” “better” and “best” technology options that are available today and being deployed in packaging pressrooms:

• Replacing densitometers with spectrophotometers
• Adding press-side color quality software
• Automating color measurements with an inline spectrophotometer

Now, let’s take a closer look and see just how each of these technology options can increase color accuracy, shorten makeready times and allow packaging printers to reclaim their profitability.

Good: Replacing Densitometers with Spectrophotometers

Quite simply, densitometers do not measure color and are incapable of reporting a color’s CIE Lab values. This also means densitometers cannot objectively describe how a color is perceived by the human visual system or quantify the perceived differences between two shades of colors using a Delta E formula. For this reason, switching from densitometers to spectrophotometers is an absolute must for packaging printers. Otherwise, press operators cannot know when contractual brand specifications have been achieved or what color changes are required to meet them.

Making this shift is relatively easy for press operators because spectrophotometers can still report all of the familiar densitometric functions like solid ink density and TVI, which are important process control metrics, and the instruments are operated and handled in the same way as densitometers. However, in addition to reporting densitometric and colorimetric values for measured samples, spectrophotometers have many more features and functions that can help guide operators to faster and more accurate color matches.

The workflow using a spectrophotometer to check color accuracy is extremely similar to that of using a densitometer. On a flexographic press, the press is stopped and a sample is cut from the roll; while on a sheetfed press, a sample is simply pulled from the output stack. The printed sample is then placed on a flat surface where it can be measured with the spectrophotometer.

Now, the press operator selects the measurement mode on the instrument (density, TVI, CIE Lab opacity, etc.), aligns the measurement aperture over the sample to be measured, initiates the measurement, and the results will be shown on the instrument display. If users wish to see other measurement information from this same sample, they will then need to change the display mode on the instrument.