Details:
Summary:
“Brand colors” are a key component to a brand’s visual identity. Traditionally, the brand colors are defined with spot colors. While a brand color can be used in various types of packaging, the formula of the printing ink is adjusted accordingly based on the substrate, application, finishing, etc. to maintain the accuracy of the brand color. With the individuality of the color formula, the print manufacture can accumulate many leftover spot-color inks. Meanwhile, more waste was generated during make-ready and in the process of changing inks on press when dealing with multiple jobs that require various spot-color inks. With sustainability in mind, more and more printers are looking for ways to reduce waste and to optimize material management. The extended color gamut (ECG) process printing offers just the solution to achieve a sustainable production.
The ECG printing is a print reproduction process that uses orange, green, and violet inks in addition to the traditional cyan-magenta-yellow-black (CMYK) process inks. The three additional inks serve to extend the color gamut. The use of an ECG inkset to replace spot colors reduces in press wash-up time and spot color ink inventory and improves productivity with the options to gang up different brand color jobs. But some brand owners and printers hesitate to implement the ECG process. They are not sure if the brand colors can be reproduced accurately using ECG process printing and if the brand colors will fluctuate more through the production run.
In this study, 25 predefined spot colors would be reproduced using the ECG process printing workflow. A press trial was designed to investigate the color accuracy of these predefined colors and to investigate how well these colors performed through out the production run by analyzing “within the sheet” and “from sheet to sheet” variations.
With a joint project between Sun Chemical and ESKO and with Dr. Abhay Sharma as an academic consultant for the data analysis, the ECG press trial was conducted at Sonoco Institute, Clemson University, Clemson, SC, using Esko Equinox color management software and separations, in conjunction with Esko HD screening and XPS Crystal platesetter. Printing was done on the seven-unit OMET VaryFlex 530 flexographic mid-web press with UV LED flexographic ECG process color inks and the coated paper label house stock. After the calibration and profiling of the press condition, the production run was prepared using the resulted profile to convert the special designed press form that contains spot colors into ECG process colors through ESKO Equinox system. The run was kept at a production speed and for more than 50 minutes continuously. At the completion of the run, the substrate roll was rewound then a sheet was cut and collected at every 150-foot length. A total of 35 sample sheets were collected for data analysis.
Without using any spot color inks, the accuracy of 25 chosen spot colors can be achieved to an average of ΔE00 1.6, with no patches having an error greater than ΔE00 of 3. The average color variation through the press run was ΔE00 0.4 for lead-edge vs. tail-edge and ΔE00 0.33 from-sheet-to-sheet. Variation between left and right sides of the sheet is slightly higher with the maximum ΔE00 of 2.16 and average of 0.59. The variation on press was mainly caused by the repeatability of the black ink printing unit.
The consistency can possibility be improved by resolving the repeatability issue on the black unit. The study also confirmed that the variation on press for ECG printing was not caused by the color distance to the hue line of the process inks. It was not caused by adding orange, green, and violet inks into the color separation. It was not caused by the total area coverage of the inks. On the other hand, ECG process reduced the number of color inks needed and the ink coverage. ECG provides a way to an efficient production and reduces makeready time and the material waste.
For printers to implement ECG process printing for brand colors, the achievable colors can be reproduced in a consistent and accurate manner provided with a good and repeatable printing process condition and with proper calibration and profiling. If a printer has a repeatable system for a CMYK process printing or for spot color printing, the printer will have no issue to reproduce special colors consistently using the ECG workflow.