In the beginning of 2020, I was awarded the Gary Hilliard FQC Scholarship to conduct a research project.
My instructor and I chose to begin determining patterns of variable combinations that produced the most desirable prints.
Our goal with these test prints and combinations was to find out which combination of variables would make white film ink lay down as opaque as possible. We hoped to do this by providing data based on test runs, as well as visual inspections, of 80 different variable combinations, while running white ink on a film substrate with unbleached liner.
Measurements were to be taken using a spectrodensitometer from the patches (see Image 1) that were printed to compare the opacity of each patch. The hope: to find a way to log data that, in the future, could help printers cut down on ink consumption and material waste during trial runs in preparation for a live job.
All images courtesy of Micah Purser
Our focus for this project was running white ink on film, though we ran the same set of variables and tests on an unbleached kraft substrate, both provided by Avery Dennison. The non-film substrate was incredibly absorbent and showed as being more opaque through the spectrodensitometer, despite the ink laying down patchier, due to more ink being held in the paper. That rendered results on the unbleached kraft inconclusive.
Once this was realized, we returned focus to our film substrate. We observed how the surface screening we used on our plates affected the film as a result of the substrate being less absorbent. We ran four test runs on the film, each yielding 20 variable combinations per run.
Test Runs
For the test runs, we had two ink stations: a black and a white. Most of the unchanging variables in this project were in the black ink stations. Constants were the anilox roll, the FTH (flat top hard) plates, and the 3M E1015 mounting tape. We put the black ink station before the white, in order to print the white over the black patches for measurements. The black anilox roll had a bcm of 4.85 and a cpi of 360.To get the 80 variable combinations we ended up with, we used a high-volume banded anilox roll in the white ink station (see Image 2). The banded anilox gave us the different columns used to create test patches. We had a portion of the white ink lay down on just the substrate, as well as a portion lay down over a strip of black ink.
There were three changing variables within this project:
- Three surface screening patterns numbered from bottom to top on our test prints; the bottom being no surface screening, the top being what we called Pattern 3
- Two types of 3M mounting tape: E1015 firm, which was also used in the black ink station, and E1815 medium firm
- White ink plates. We used two different plate types: FTH (or Flat Top Hard) and FTM (or Flat Top Medium)
After running the test prints with the variable combinations noted, we moved on to the measuring and data portion of our project. The black strip of ink we added to our project was the key to being able to take measurements. We used this in measuring the opacity of the white by using the Contrast Ratio on an X-Rite eXact spectrodensitometer. We then logged all measurements into a spreadsheet to create charts to see the difference according to each of the variables. These charts were a simple compilation of the spectrodensitometer measurements according to which anilox band and surface screening patterns were used for the measured patches.
These charts showed us that the most desirable prints came from our first two test runs done with the FTH plates on both E1015 and E1815 mounting tape. The combination of the surface screening with the FTH plate material helped the ink to lay down evenly and opaquely.
To reiterate, our best set of variables out of the 80 combinations ran across four test runs was the group of anilox band patches that had the first surface screening pattern with E1015 and E1815 mounting tape used on FTH plates. This test group showed the cleanest print with the least mottling, while still exhibiting high opacity on our white ink laydown. Both visual inspection and measurements with the spectrophotometer proved this group to be the most desirable.
Conclusion & Acknowledgements
This project was just the tip of the iceberg for tests that could be run across every type of printing to help lessen waste during test and live job runs by reducing materials used, making the run more cost efficient as well as decreasing carbon footprint. This could give a standard to how printers go about their live jobs while remaining in accordance with Flexographic Image Reproduction Specifications & Tolerances (FIRST), as the entire project was done using FIRST methodologies from beginning to end.
I’m sure we can all agree that the last two years have been hard. I mention this only to say that the entirety of this project was done during the COVID-19 pandemic, so we faced a few issues due to restrictions and time limitations. I ran the test prints of this project during the fall semester, which ended up being cut short by more than a month. Given more time to work on it, I would have liked to dive deeper into different forms of measurements we could have used to collect more data. Unfortunately, I was extremely limited in the time I had available in the lab.
This project would not have been possible without the numerous companies that sponsored me by either donating material to use or just giving advice on what they would do while running these tests. I also owe a huge thank you to my instructor, Zachery Blackburn, who walked with me through the entirety of this project, and my instructional lab coordinator Amber Dobbins, as well as to all the supporters of Central Piedmont Community College. From developing a plan to design to execution, these people helped guide me throughout the journey that was this year-and-a-half-long project. And lastly, a thank you to FTA and FQC for awarding me the Gary Hilliard FQC Scholarship.
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