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IWPA Conducts Waterless vs. Wet Offset Comparison Test

10 Nov 2011 8:31 PM | Keiji Obata (Administrator)
by John O'Rourke

Earlier this year, IWPA conducted a G7 comparative print test between waterless and conventional offset printing. Both waterless and conventional wet offset. The results of the test have been published in a white paper, titled: “A current comparison of waterless printing to conventional lithographic printing.”

The-32 page whitepaper, authored by Gene Langlais of Capricorn Researchundefineda board member of TAGA and a member of GAFT Research Committeeundefinedis available exclusively through the IWPA. The whitepaper is available free of charge to all current IWPA members. Non-members can purchase the whitepaper for $149.00.

The test was run on March 21-22, 2011 at Mosaic in Cheverly, MD. A common test form was printed both waterless and wet offset on the same press and under the same conditions to determine if measurable print and / or production quality differences could be found between waterless and wet-offset.

During the test, Mosaic was asked to use their pre-press and start-up procedures for both print runs, using the read outs from the SpotOn!™ system to determine when salable copy had been achieved according to the G7® guidelines, which are in line with ISO standards.

The first 30 sheets after each start-up were measured for all the pertinent values. This occurred after the initial start-up, after a planned stop at 4,000 sheets and a 30 minutes delay to simulate a lunch break, and finally after a planned stop at 7,000 sheets to wash the blankets.

Additionally, samples were taken every 100 sheets and measured for the same criteria; namely, SID (Solid Ink Density), Ink Trap on the RGB patches, GB (Gray Balance), NPDC (Neutral Point Density Curves) and L*a*b* Color compliance (Delta E*) and for TVI (Total Value Increase).

Furthermore, since 1-bit TIFF linear (and curved) tone targets were included on each test form, the 1-bit TIFF linear dots on the plates and sheets were compared every 1,000 sheets to record Dot Gain and review any signs of dot wear.

Other areas such as Ink Consumption, Fountain Solution Usage, Paper Waste and Press Temperature were monitored and measured as well.

Following are selected conclusions based on results of the print test:

  • Waterless shows advantage in color space, compared to conventional offset indicating that a slightly larger color space is possible with waterless.
  • Waterless printed with consistently lower dot gain than conventional wet-offset.
  • Start-up waste was significantly lower for waterless, requiring roughly 40% fewer sheet at start-up to achieve G7 aimpoint densities.
  • Waterless reached and maintained target ink densities on all subsequent re-starts.

The whitepaper provides documented evidence of several key waterless benefits. Purchase your copy of the whitepaper today.

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