Optimization = Prelude
At the pre-production meeting, it was revealed that Michaud, Haynes and Teufler, along with the Clemson team, staged the optimization run earlier in August. Reports indicated it stretched over some six hours and entailed a banded anilox roll test.
Holding to its stated purpose, “Identify the best combination of print variables/components to produce desired results. Determine prepress requirements, ink densities, press settings, etc.,” results did exactly that. Talk about “empowering the print crew.”
Among the determinations made and consumables choices settled on:
- Delta 2.88 for paper
- 1200, 1.8 anilox for CMYK
- 800, 2.8 anilox for PMS 207 spot
- 500, 5.0 anilox for the overprint varnish (OPV)
- 3M Soft Tape E1920 mounting back
- Flexo Concepts Orange doctor blade
- Siegwerk LED for CMYK\OPV = UV
- MacDermid ITP (in the plate) 60 plates
- Screen = 200 lpi
Michaud reported, “We hit the ground running with the optimization pressrun to explore anilox, mounting tape and plate screening variables. We had a chance to troubleshoot several real-world challenges, while determining our selection of optimum setup conditions and materials to carry forward into the fingerprint.”
Samworth added, “In addition to the traditional optimization run, we wanted to further refine the screening parameters We knew we were going with a 200 lpi screen, but we wanted to use a transitional screen with FM spots in the highlight areas to enable the job to fade to zero like the offset job. We used Esko’s Print Control Wizard (winner of a 2019 FTA Technical Innovation Award) to create a chart which we printed and measured back into the Print Control Wizard. It instructed us to use a 16 pixel FM dot (about 25-µ. on the plate) and a min dot setting of 0.3 percent. These were the parameters used for all of the following pressruns.”
Telling Signs
That’s where things stood early that Monday morning when under FIRST methodology, a fingerprint run topped the agenda. Its purpose: “Improve graphics and color reproduction specific to the press.”
In discussion, the team elected to aim for solids and tight registration in the fingerprint. It was resolved to generate desired actual curves based on an average of measurements, apply the G7 process, recognize solid hue angles, traditional screens and minimal dot fadeaways.
As the team set about “rounding the curves,” Curve Pilot and SCTV (Spot Color Tonal Value) scripts were put in play and dual fingerprints were generated.
Characterize & Control
With careful measurements taken and intense monitoring of the fingerprinting complete, time came to leverage data collected and characterize the press for the job. Process control was the order of the hour as Tuesday morning dawned.
Characterization meant creating a data set for the sole purpose of comparing our results to CRPC-6. Samworth explained, “Unlike traditional characterization pressruns, there was no intention of ever making an ICC profile from the data. The only goal was to match CRPC-6. As we were using the exact same artwork that would later be printed offset, we did no color conversion in prepress (all images were already assigned the standard CRPC-6 profile). Even the proofs would be matched to CRPC – not the profile of this flexo press characterization run. The main test target used for this test was the IT8.7-5. Formerly known at the Idealliance 1617 chart, this chart combines the IT8.7-5 with the gray scale and Black data of the P2P51.”
A lot happened on press, and it occurred throughout the day, presenting quite an afternoon fraught with challenges. Metal smears were detected, dings in one anilox identified, blade impression applied was too heavy, the ink pump went non-functional at one station, causing the deck to lock up. The story didn’t stop there.
Prominent plate seams came through on print, blade seatings were misaligned, minutes ticked off with a few hours succumbing to getting the gloss just right. And the pièce de résistance—that locked deck—required that it be eliminated and color stations relocated all up and down the press.
Somehow it all came together and by day’s end, just after 4 p.m., characterization and fingerprint run samples were both ready. It was time to make plates for the actual job. The overnight affair saw Clemson’s Mekrom EVO processor, and Esko CDI Crystal 4835 imager and XPS Crystal exposure unit, deployed.
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