Gray Balance Control in Sheet-Fed Offset Printing

Newspaper printing can be controlled by visual gray balance assessment, a procedure which is widespread among newspaper printers in Sweden. In sheet-fed offset today, there is no fast and efficient way to process control the sheet-fed offset-press during production without using advanced online-systems. The control patches which are used in sheet-fed offset during the production often lack the possibility to assess gray balance, these usually work to determine full-tone ink densities and dot gain. The first objective of this study has been to evaluate the subjective quality experience (and objectively measurable factors) of print, where the quality control has been carried out based on gray balance control in sheet-fed offset. The second objective was to implement gray balance as a practical tool for the printers for a fast visual quality control in a sheet-fed offset printing. The study has shown that: 1) The gray balance can be used as a control parameter for control of quality in sheet fed offset. 2) A faster start-up and a more reliable print quality (fewer variations during production) can be achieved. The printer and the customer have access to a tool which facilitates communication, generates fewer misunderstandings, leads to less product returns and less production losses. With this tool it is easier for the printer to visually detect deviations without time consuming physical measurements. Also troubleshooting is easier; printers know instantly where the deviation is and can attend to it immediately.