INVESTIGATION OF UV ARTIFICIAL AGEING OF OPTICAL CHARACTERISTICS OF PRINTED IMAGES

Over time, the printed images are ageing, and this may be due to different factors like natural ageing of paper and ink, temperature, humidity, sun light and human intervention. The main goal of this research is determination of the influence of artificial UV ageing on the colour characteristics of the printed images for mostly used papers, inks and offset printing technology. Two types of papers have been selected for the experiment in terms of their wide use and distribution on the all printing markets – uncoated offset paper and mat coated paper. Printing test evaluation form designed for this research test has been used. In real printing conditions in printing houses on two selected papers have been printed the test form with big number of control strips and elements for colour measurements. The optical properties of papers, colour characteristics of test charts for used papers, inks and printing presses were measured before and after artificial UV ageing time periods. The colour differences, changes of colour gamut volumes, 3D and 2D gamut are calculated too. Great changes in the colour characteristics of the printed images have been identified. The results show huge changes in many of critical colours from human perception point of view.