A Survey of Offset Lithography Print Defects

Abstract

Offset lithography printing, given the multitude of material choices, produces more frequent print defects, relating to nonconforming materials. The International Organization for Standardization has developed several standards to define the quality of graphic images, based on various perspectives such as tone, colour, resolution, contrast, etc. The evaluation of image quality traditionally has been one of the methods of visual defect detection, as assessed by the customer. The presence or absence of undesired visual print attributes within a final product would lead to the rejection or acceptance of a job. In this survey, the highlighted print defects on the visual aspects of a print are inclusive of banding, colour cast, colour non-uniformity, colour variation, ghosting, graininess, hickeys, mis-registration, moiré, mottle, poor line quality, poor trapping and poor text quality. The research revealed that the quality of the end product in printing will normally be judged by its visual impression but the visual impression of printing will be determined to a large extent by the sum of the quality of work at each stage of production. Quality control is concerned with ensuring that the materials worked upon or with at each stage of production are within defined limits.