Printing methods contrast control

In contrast to writing, drawing, marking, and conventional printing methods, inkjet printing is a true primary, non-impact process. Liquid ink droplets are ejected from a nozzle under digital control and directed onto surfaces such as paper, plastics, metals, ceramics, and textiles to form a character or image [2,3],... 

Barium sulfate (BaS04) has an industrial relevance due to its whiteness, inertness, high specific gravity, and optical properties, such as opacity to UV rays and X-rays [164-167]. It is mainly used as a radio-contrast agent, filler in plastics, extender in paints, coatings and additive in pharmaceutical products, and in printing ink. Nowadays, interest on this material has been renewed with the development of methods to produce nanosized particles, supraparticles of a well-controlled number of nanoparticles and mesocrystals that mimic biomineralization processes. 

Inkjet photographic prints, especially those printed with dye-based inks on porous media, are subject to rapid dye fading when exposed to ambient levels of ozone (5). In contrast, the fading rate is much slower when dye-based inks are printed on sweUable media and moreover, when pigment-based inks are used. High concentrations of ozone under controlled conditions have been used for testing in order to establish a standardized test method for accelerated aging. There is a relationship between the concentration of ozone and the time of exposure. 

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