Printers looking to improve their repeatability and consistency did well to attend Forum 2019‘s “Gaining Control of Your Process: The Fingerprint,” chaired by Zachery Blackburn of Central Piedmont Community College.
Flexo 101: Preparing for a Fingerprint
Mark Mazur, FTA Hall of Fame member, discussed how a printer can prepare for a press fingerprint.
“I hate the term fingerprint, because a fingerprint never changes,” he pointed out, relating the term to calibration. “What you’re really doing, is you’re calibrating your system.” He offered three questions for printers to ask themselves before beginning the process:
- Where are you?
- Where should you be?
- How do you get from where you are to where you should be?
Mazur said the single biggest point of confusion he runs into is separating optimizing and fingerprinting, partly because the difference is not that simple. Preparing to fingerprint a press means two things: making sure you have optimized every component of your printing process and using the data from the optimization to get the best fingerprint information. “You should not be surprised when you run your fingerprint—You should know all these things ahead of time,” he pointed out
Covering a pair of ink film optimization examples, Mazur showed how to plot a and b values, generate curves and then apply those curves to a fingerprint. He spoke to few of his personal pet peeves: Knowing, before running any fingerprint target, how a printer will measure the target, and being ready to record everything. “I guarantee you that when you leave that room, you think you will remember everything,” he said. “You won’t!”
Fingerprinting: The Foundation for Repeatability. Determining YOUR Densities and the Importance of Hue Angles and Gray Balance
Shawn Oetjen of Flexographic Tech followed with a focused explanation of how a printer can find its own, specific densities.
Oetjen began with a print-focused understanding of density as a measurement of ink film thickness. “This does not tell us anything about color!” he cautioned. He then spoke to FIRST-recommended density targets, reminding printers they are starting points and not “do or die” numbers.
Oetjen offered a brief list of rules to follow when fingerprinting a press:
- Running at production speeds
- Running for more than 15 minutes
- Focusing on repeatability (pH, viscosity and clean components)
- Documenting all settings
“What if we could measure the color of the ink?” he asked the audience, before going over how to use hue angle in conjunction with density to paint a more accurate picture of how a process ink is performing.
Once a press’ performance is dialed in, with density and hue angle locked, it’s time to calibrate by adjusting dot gain through curves. Oetjen covered traditional CMYK curves as well as Near Neutral Calibration (NNC).
He stressed the most important result of a fingerprint is repeatability, pointing to operators who choose their personal favorite mounting tape as a hiccup to that repeatability. Training operators on the “why” of the fingerprint, as well as having solidly developed SOPs, are means to prevent this.
Spot Color Tone Value Practical Implementation
The “Godfather of Color” Steve Smiley, of SmileyColor & Associates LLC, gave an overview of Spot Color Tone Value (SCTV), as well as how to both communicate it across suppliers and implement it in software and measuring devices.
Smiley started with a summary of ISO 20654, aka SCTV. “It’s a big win for liquid ink technology and for packaging,” he explained. “We can make everything look the same using SCTV.” He followed with a semi-technical overview of densitometric TVI and traditional TVI, juxtaposing them to SCTV with examples using Reflex Blue and PMS186.
“Traditional TVI aligns measurement devices, but not appearance,” Smiley explained, recalling that not all devices use the same filters and because of that, results can vary. In contrast, SCTV aligns in appearance with Adobe and is calculated with defined colorimetry.
He offered three points concerning how to define color aims in SCTV:
- The aim curve is linear; a 10 equals 10 percent, a 25 equals 25 percent, a 50 equals 50 percent and a 100 equals 1.0
- It opens shadow to smooth transitions in dark colors
- It aligns with digital and analog printing technology
Moving on to tools and software that can measure and make use of SCTV, Smiley covered a number of options. He closed with an explanation of SCTV for color management and using it in conjunction with iccMAX.
Control Points of the Fingerprint. Establishing Feasible Targets
Closing the fingerprint-focused session was Robb Frimming, print services director at Schawk.
Frimming reiterated that the primary objective of the fingerprint trial is to measure and record the print characteristics of a particular press, operating with specific settings and materials. The specific settings and materials are determined, in part, by the customer’s design requirements (substrate, ink colors, design elements) and by printer experience or optimization trials (best anilox for each deck, optimized ink formulation, best mounting tape, etc.).
“It’s time to make some decisions,” he told the audience. Chief among them: a substrate (after trialing options) and ink (after trialing unique ink systems), making use of Substrate-Corrected Colorimetric Aims (SCCA), and a measurement mode (M0 or M1).
“This is more than just what you’re doing inside your pressroom—It has huge influence on the rest of the workflow,” he stated. Frimming posed a possible scenario where, by standardizing methods, premedia companies could share data for a given printer.
Frimming closed by urging printers to take notes and capture data as often as possible. “Data is your sword in the battle,” he said when discussing how frequently to run a new fingerprint. If that data is consistent, and no part of the process has materially changed, the need may not exist.