In Electrophotography printing technique with liquid toners, large quantities of ink are deposited on photoreceptor. Voltage variations during the development phase (ΔV=200V) will directly influence the thickness of ink layer on photoreceptor. Optimal reproduction is achieved when smallest image elements (screen dots) have smallest possible diameter, and respectively higher optical density. Suitable method for reproduction analysis is based on spectrophotometric measurement of halftones and on optical densitometry. By adjusting the voltage during development (II. phase) will allow largest manipulation of color (ΔE RR = 10.01). Optimal results are achieved with voltage of -125 V. Under this conditions, average printed screen element had average diameter of 56.9 μm and a maximum reflectance of R=33.50%. Variation of voltage on other two developing devices affect only slightly the color reproduction (ΔE DEV =1.26; ΔE SQU =0.94.) and have lower impact on the size of screen elements (Δd DEV =8.1 μm; Δd SQU =4.1 μm).

Light and gas fastness are two very important aspects of print quality. The aim of this proceeding is to determine light and pollutant impact on the gamut of prints through exposure of samples to artificial, glass filtered and direct sun-light, as well as common gas pollutants. Exposed samples were analysed by densitometric and spectrophotometric methods and statistically processed in order to determine the correlation between time and type of exposure and gamut changes. The results show a significant impact of combined direct sunlight and pollutants on prints. Beside the scientific aspect, these results could be used as guidelines for manufacturers and printers to improve the quality, while still maintaining low production costs.