Enqi Zhang

Abstract

The original intent of this research was to verify that a new method - called the Little Joe method in this report - could be used to verify that CMY offset inks conform to ISO 2846. This method would use less time to generate multiple ink film thicknesses (IFTs) than the traditionally used ISO 2834 method. With a graduated gage, a Little Joe proofer can be used to produce multiple IFTs on a single sample. However, the absolute thickness values for those IFTs are unknown. Therefore, to calibrate these unknown IFTs, a calibration curve that relates IFT and optical density should be used. Such a curve would have to be built based on samples produced by the method described in ISO 2834 using an IGT printability tester. The question is: will both methods (the traditional ISO 2834 method and the Little Joe method), either accept or reject a given sample? This research found that the same IFTs on both samples do not have the same colorimetric values. The ink film was not as smooth on the Little Joe prints as it was on the IGT prints. The presence of tiny white spots throughout the Little Joe sample add a gray component to the color. The difference in smoothness of the ink layer on the Little Joe proofer comes from the ink not being "worked" as much as it is on the distribution rollers of the IGT printer. Therefore, the ink is less liquid and not able to completely spread out and cover the paper. The answer to the research question is that the two methods do not both either accept or reject a given sample. Towards the conclusion of this research, Professor Franz Sigg and the researcher made some improvement to the traditional ISO 2834 method and eventually invented a more efficient method: the modified ISO 2834 method. A high input volume of ink (0.1 cc) was applied to the IGT inking unit. Then, while the inking unit was kept running without adding new ink, the disc was weighed before and after each print and was then re-inked to made another print. As samples were printed, the ink on the inking unit was reduced, producing prints with progressively thinner ink film thicknesses in rapid progression since no cleaning was needed between prints. This allowed the prints to be produced in a much shorter time than with the original ISO 2834 method. The result of the modified ISO 2834 method agreed with that of the original method within a tolerance of 1 DeltaE. Therefore, both methods can accept or reject a given sample at the same time.

Library of Congress Subject Headings

Printing ink--Testing; Color printing--Testing; Printing ink--Standards

Publication Date

10-1-2012

Document Type

Thesis

Department, Program, or Center

School of Media Sciences (CIAS)

Advisor

Sigg, Franz

Comments

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TP949 .Z42 2012

Campus

RIT – Main Campus

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