In the master’s thesis, we analysed the lightfastness of printed samples on folding carton
packaging used for hair dyes. The aim of the research was to evaluate the influence of
pigments, ink manufacturer, and surface properties of the printing substrate on colour changes
after exposure to artificial aging, as well as to determine the relationships between optical,
mechanical, and surface properties of the prints.
The experimental part included the analysis of four printed samples of different colours on two
related printing substrates. Before light exposure, we determined the basic and surface
properties of the materials, such as thickness, roughness, and porosity, and evaluated the
rubbing fastness of the prints. The samples were then subjected to artificial aging in a chamber
with a xenon lamp at time intervals of 8, 16, 24, and 48 hours. Prior to exposure and during
the intervals, spectrophotometric measurements of colour values were carried out, and colour
differences were calculated. Based on the results, the samples were also assigned a
lightfastness rating. Additionally, we analysed the surface before and after exposure using a
scanning electron microscope.
The results showed that the printing substrate yellows after exposure to light, which can affect
the perception of colour changes in the print. Significant differences in lightfastness were
observed among the individual samples. The largest changes were detected in one of the
beige samples, while the other beige sample exhibited very high stability. The orange and blue
samples showed moderate lightfastness. It was found that changes in surface structure are
not necessarily directly related to colour differences.
Based on the results, it was concluded that the lightfastness of prints is significantly influenced
by both pigment properties and the characteristics of the printing substrate, with the choice of
pigment manufacturer playing a very important role. The results confirm the complexity of the
studied problem and indicate the need for a comprehensive approach when selecting materials
for packaging printing.
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