Waterless vs. Conventional
Tested and Proven Superior Technical Performance
Waterless printing is widely recognized as offering significant advantages over conventional wet offset. A recent G7® comparative print test bears this out.
The International Waterless Printing Association (IWPA) commissioned a test in March 2011 to generate fresh data comparing several key print quality metrics for waterless and conventional offset. Gene Langlais of Capricorn Research analyzed the test results and published his conclusions in a white paper called “A Current Comparison of Waterless Printing to Conventional Lithographic Printing.” Below is an excerpt from the white paper.
A Current Comparison of Waterless Printing to Conventional Lithographic Printing: Executive Summary
Although both print processes yielded acceptable commercial quality, the waterless printing process demonstrated better technical performance in several areas as described below.
Both the conventional and the press runs yielded acceptable quality prints based upon the G7® guidelines.
Since both tests used G7® color control methods and recommendations, both sets of printed test sheets were visually similar in appearance.
The color gamut shows a slightly larger color space for waterless over conventional.
When the IT8 data was mapped on the CIE color space curve, waterless showed an advantage over conventional in this test comparison in the red, green and blue areas.
IT8 Color Range Comparison Between Conventional and Waterless
Conventional printing color shown in RED, Waterless printing color shown in GREEN.
The Neutral Print Density Curve (NPDC) Color Match and Stability is better for waterless than conventional.
This is especially evident with respect to the closer match of the CMY Gray curve to the target values set by the G7® / ISO standards. There were also fewer fluctuations from this important target during the press run.
Additionally, when inspecting the color trending through both runs for a comparison of K at 50% and of CMY Gray at 50%, once again waterless appears to be closer to the aim points for achieving a Neutral Density Gray—a key factor in colorimetric control for G7® compliance.
Figure 4-18: Comparison of 50% CMY Gray and 50% K Only Gray,
Conventional (top) and Waterles (bottom) The trend for Black 50% and CMY Gray 50% are compared over the entire 10,000 sheet press runs.
These graphs show that for waterless, CMY 50% gray is closer to the targets set for CMY 50% and for Black 50%; also, the individual data points have less scatter around the trend curve defined.
The conventional graph, on the other hand shows more scattered points with wider variability and more distance from the set point curves.
Waterless appeared to show tighter color control upon inspection of ΔE.
When looking at color stability trends throughout both runs for all of the color values (Cyan; Magenta; Yellow; Black and CMY-neutral density Gray), waterless appears to be more stable, based upon a tighter clustering of data points and with less fluctuations with respect to the aim points in question. Waterless also showed superior performance in matching ΔE targets for RGB over prints and CMY-neutral density gray.
Figure 4-13: ∆E Deviation Trends
Conventional, Sheet #225 - #10,000 (top) and Waterless, Sheet #130 - #10,000 (bottom)
Sheets measured using X-Rite i1 Pro Spectrophotometer and SpotOn!TM color strip
Average Dot Gain/Total Value Increase (TVI) measurements for waterless and conventional seem to indicate some advantage for waterless.
When the CMYK dot gain curves were measured and averaged, both Black and Cyan curves indicated a lower dot gain in the waterless sheets. This was apparent over a broad area (~2–5% decrease); Magenta showed no significant difference; and Yellow showed a slight increase (~1–2%) around the mid-tone areas.
This advantage showed throughout the test run, despite the fact that waterless Black and Cyan showed an appreciably higher Solid Ink Density (+0.16 for K; +0.13 for C; +0.04 for M; +0.05 for Y) than did conventional. (Note: The waterless SID values were much closer to the G7® targets.)
During make-ready, waterless showed advantages in reduced make-ready time and reduced paper waste.
The make-ready time for the conventional press run took 35 minutes and consumed 866 sheets of paper. Whereas, the waterless make-ready took only 17 minutes and consumed 466 sheets of coated paper (only 58.3% of the paper used in start-up compared to conventional). This computes to a saving of 18 minutes and 400 sheets of paper (25”x 38” in 100# Gloss).
During the initial start-up and during the planned restarts, waterless appears to reach and maintain stability faster than conventional.
All 30 sheets after the start-up and each re-start were scanned for closer inspection of color data. The color roll-up back to the target values after restarts are no more than few sheets different between the two plates.
However, when the trend charts for NDPC @75% are examined, they indicate that the Dot% reading for conventional printing appears to be more unstable, oscillating substantially, from sheet to sheet for the CMY Gray and even more so for the Black.
Figure 4-20: Comparison of First 30 Sheets of Roll-up for K and CMY Gray at NPDC 75%, Conventional (top) and Waterles (bottom)
Sheets are measured using X-Rite i1 Pro Spectrophotometer and SpotOn!TM color strip.