The Investigation of light-stability of color proofing materials

Lightfastness is the permanence of a photograph, or any colored material, under the influence of light {Encyclopedia of Photography, Third Edition, p 438). Thus the lightfastness test is an investigation of changes, mainly in terms of density, of any colored materials due to light. From accelerated light-stability tests, information about the light stability of color prints can be obtained. To produce the desired amount of image fading, special lightstability test units equipped with high-intensity light sources, where test strips can be exposed for days, weeks, months, or even years, are required. The temperature of the samples and their moisture content must be controlled throughout the test period, and the types of light sources must be chosen to yield data simulating those obtained under conditions of normal use. Many accelerated tests have been devised that attempt to simulate in only weeks and months the fading that will occur during many years of normal display and storage. High-intensity light-stability tests expose a photographic print to light that is many times brighter than normal indoor illumination levels, speeding up the fading that would gradually take place during many months, or years of display at normal indoor illuminations. This test is intended to simulate normal office illumination situations. Fluorescent lamps, which generally provide more intense illumination than tungsten lamps, are usually the primary source of illumination in offices and public buildings. When fluorescent lamps are present, they may contribute significantly to the fading of displayed prints. Printers, publishers, photographers, and other consumers need to know the stability characteristics of a color material before they purchase it in order to select the most stable color material and proofing device available. The purpose of this thesis project is to investigate the light-stability of four prepress proofing outputs including dye-sublimation, silver-halide/dye-diffusion, electrophotography, and ink-jet, with traditional chromagenic color photography prints, and regular CMYK four color sheetfed lithographic prints under fluorescent illumination. Through an accelerated lightfastness test, the differences in light-stability between conventional color prints and other color printing processes were found out. Thus the thesis project resulted in the rejection of the hypothesis for all given color printing systems