Paper is a flat, hygroscopic, anizotropic, double-sided, viscoelastic, and non homogenous material, which is used on a daily basis. Its usability most often depends on grammage, which provides and enables different physical-mechanical properties that affect some of the optical properties, as well.
The main purpose of this diploma thesis was to emphasise the the meaning of the paper properties in regard to grammage on the colour reproduction in laser printing and thus achieve a better print repeatability.
The empirical part was based on the testing of eight paper samples; their grammages were 90, 100, 120, 140, 160, 200, 300, and 350 g/m2. The applied reference paper was office paper with the grammage of 80 g/m2.
The measurements were divided into two parts – the measurements of optical and surface properties, and the spectrophotometric measurements. To determine the inflluence of grammage on the paper properties, ISO brightness, CIE whiteness, and opacity, had to be calculated. Additionally, the specular reflection and roughness had to be measured, and the fiber distribution in samples had to be determined. Then, measurements on colour reference charts had to be taken and colour differences calculated among the prints on different paper in regard to the reference sample.
The results showed that the effect of grammage is greater in some properties than others, and that there is a link with both the optical and the surface properties of the paper. The link is most obvious in the measuring and calculating of the ISO brightness, the specular reflection, and opacity. The mentioned properties also affected the colour reproduction on the printed charts, in which some of the differences could be seen optically. The colour value graphs showed the colour difference rising along with the grammage, especially in the colour tones of orange, brown, purple, and black. We predict that the higher temperatures of toner fixing had a bigger effect in paper of higher grammage. A more quality and repeatable prints could be enabled in small-format laser print with small circulations by observing these findings in everyday print.