The Influence of the position of a color control bar on a form when determining the most appropriate location to measure variability in solid ink density and dot gain of a printed product

This study proposed to determine the most appropriate place to measure variability in dot gain and solid ink density on a form using color control bars. The study developed a form that entailed three GATF/SWOP, 133 line color control bars placed strategically at the lead, middle and trail edges of the sheet. The test set specific density standards to control to, and while these densities were being controlled, samples were obtained that represented a typical press run. Each of the control bar set-ups was treated as a separate press run, allowing the press operator to change the set densities to the next control bar once the samples were pulled. Five samples were averaged to obtain one sample for that particular sample set. That sample represented one of thirty for one entire press run. Every sample's average density and dot gain was determined, as well as its accuracy, precision, and range. A one-way analysis of variance was used to determine difference between control bar data. Through the statistical tools listed above, the variability in each position of the control bars was determined. The results revealed that both the density and dot gain positions at the trail edge for cyan, black, magenta, and yellow were the most consistent, most precise, most accurate, as well as containing the smallest range of data. In conclusion, based on this study, the trail edge may be the most appropriate position on a form to consistently control a web offset press. The data that were obtained when the middle was being controlled also showed this to be a good location for the control of the press.