Taking the measurement data from the fingerprints, we averaged the spectral data for all measurements, compared it to the average and removed outliers with readings above a Delta E 2000 of 10. Next, the data was smoothed in Heidelberg Color Tool v. 15. The smoothed data was compared to the averaged data to make sure no drastic changes were taking place. The average Delta E 2000 was 1, with a max of 3 for all of the 26 datasets, indicating no significant change was caused by the smoothing.
The data, now averaged and smoothed, is in the format that can be opened in Curve software. Curve 3 was used to create the curves, then apply curves using its virtual press module. The VPR mode in Curve acts like a confirmation pressrun, applying the G7 curves to the linear One Run target.
Pictured in Image 6 is an example of one of the G7 curves derived from the smoothed, averaged data. These curves are used in plate production to align the press to G7 tonal aims and neutrals. After all datasets were G7 calibrated, the data was compared to the CGATS21/ISO 15339 datasets. For each substrate we tested and rendered a similar appearance to the standard dataset.
This procedure was done in coated and uncoated. The averaged coated aligned with CRPC 5 within a Delta E 2000 of less than 3, while the uncoated aligned with two datasets: CRPC 2 and CRPC 3. Some of the uncoated substrates had optical brighteners aligning with CRPC 3. Substrates without optical brighteners aligned (OBAs) fit with CRPC 2.
Conclusion
Coated aligns to ISO 15339/CGATS 21 CRPC 5. Image 8 shows alignment between CRPC 5 and postprint coated. Each pressrun was an average Delta E 2000 of greater than 8 from each other. This can be clearly seen in the color variation in Image 9. Adding NNC G7 calibration aligned each printer to the CGATS/ISO Standards.
The final results suggest that, rather than using custom proofs and profiles for postprint, utilizing standard profiles and files for proofing and alignment by the printers using NNC curves will provide a superior product, aligning CPCs across all products. This is preferred to having custom profiles for each printer, press and substrate.
What this means for printers is these CRPCs align with Flexographic Image Reproduction Specifications & Tolerances (FIRST) and ISO 12647-6 flexographic printing.
Proof to Press Match
One of the biggest issues flexo printers face today is receiving a different custom proof from every CPC or supply chain partner. Utilizing the CRPC that is appropriate for their substrate and printing condition, in most cases the printer can develop curves that align with ISO standard proofs. This eliminates a CPC having to approve multiple proofs for multiple printers. The printer can be responsible for its curves and proofs.
This methodology has been used in the offset industry for more than 10 years. With the new plate/screening/ink technology we are using in flexo, we can print as well or better than any other printing process We have tested and proven wide web flexo prints to CRPC 5, narrow web flexo prints to CRPC 6 and now corrugates prints to CRPCs 2, 3 and 5 (depending on substrate), all with the common appearance our CPCs require, using the same files and streamlining the process.
We all know value add can be applied for each process or file and that should still be done, but rather than focusing on custom proofs and profiles, we can align using these CRPCs. Applying a plate curve can deliver aligned aims, printing and process control.
The aim for printers is not their custom press profiles, but the characterization data delivered in the PDF/X, per ISO 12647-6. Proofs can be made anywhere in the world. The printer can print every day to the same proof, not custom proofs made by fingerprints which isolate one point in time, one operator and one set of environmental conditions. As printers’ jobs in the supply chain get easier, they now need to communicate to their suppliers which (of the seven) CRPCs should be used. This eliminates the use of—literally—millions of custom specified profiles. Allowing the printer to print the same every time using only CRPC truly streamlines their process.
We urge you to think about how this can simplify your process, make your customers happier and increase your margins. What do you have to lose?
About the Authors: Steve Smiley, process optimization specialist for packaging, is a 38 year industry veteran involved with print, premedia and packaging brand solutions. Working with numerous major CPCs, printers and suppliers, he has developed tools to assure brand consistency throughout the world.
Steve is the principal of SmileyColor & Associates LLC, a solutions provider working with CPCs and their supply chain, providing process control audits to ISO standards aligning supply chain partners. Using G7 and G7PC training along with ISO standards allow audits and training to align suppliers for consistent results globally. As a brand manager, Steve has developed the tools for physical and digital standards to define common ingredients and aims across supply chain partners, along with supporting documents ISO 17972-4 CxF/X-4.
Steve is the chair of Idealliance’s Print Properties and Colorimetric committee, cochair of CGATS, chair of GWG Colour Committee, convener of ISO TC 130 WG2 for workflows, and a U.S. expert to ISO TC130 WG3 Metrology, WG4 Media and Materials, WG11 Carbon Foot Assessment and WG13 Conformity Assessment; he is also a 15 year ICC member, executive on the FQC Committee and an Advisory Board member for Clemson University. He is the recipient of the Holzinger Award, FTA President’s Award and Clemson Top Cat Award. Steve has a degree in photography.
Shawn Oetjen is the flexo trainer/waste reduction coordinator at Advanced Web Technologies in Minneapolis, MN, where he oversees their unique cooperative training program. He graduated from Clemson University with a B.S. in graphic communications.
Shawn possesses a wealth of knowledge and experience from working in various capacities within the flexographic industry, including education, production, technical service and sales. He has a keen knowledge and understanding of the flexographic process from start to finish. Shawn is active in various industry committees and is FIRST Level II Press Operator Certified.