Photodegradation of the ink‐jet prints is a complex process in which many external and internal factors are involved. Nevertheless, the role of colorants and various accompanying substances in the ink is often overlooked. Our research work aimed to determine the fastness of water‐based ink‐jet inks in aqueous solutions. A printing ink often contains a complex mixture of colorants to achieve optimal optical properties of color and a suitable fastness of the print. Therefore, we investigated the composition and stability of cyan, magenta, yellow, and black inks under the influence of UVC light in the presence of oxygen as well as in an inert environment based on TLC chromatography and spectrophotometric analysis. The process of photodegradation was evaluated based on ink amount and half‐life. According to the results, the majority of inks consist of at least two colorants that differ in color and polarity. The results have shown that the presence of oxygen negatively affects the stability of inks; therefore, the inert atmosphere prolongs the durability of ink in water solution.

Reading is a fundamental process and enhancing legibility is crucial for improving the reading experience. There is a growing interest in improving legibility, with new applications such as bionic reading. To investigate the legibility of texts in the bionic format, we tested two groups of participants, that is, younger readers (students) and older readers (middle-aged). Two widely used typefaces designed for on-screen reading were used to assess legibility, that is, the transitional typeface Georgia and the sans-serif typeface Verdana. The reading was tested with an eye-movement tracking device. Bionic reading was developed for on-screen reading; however, we were interested in whether it could also be used as a print typeface on paper. The results showed that bionic reading affects the reading time, that is, the reading time is longer. In addition, the Verdana typeface is faster to read than the Georgia typeface. Moreover, it was found that there is no advantage to using bionic reading for texts on paper. Older readers read faster on any medium and in both typefaces in the non-bionic and bionic format. It cannot be stated with certainty whether bionic reading is favourable or not, as the results of comprehension and memorisation do not suggest that they are affected in the same way. Further extensive testing is required. We propose extensive testing with different typefaces and type sizes, including people with dyslexia and ADHD, especially with younger readers to refine the bionic reading applications and understand their impact on enhancing the reading experience.

The durability of the materials is often limited as they fade under the influence of external factors, particularly light. The present research aimed to study the photodegradation of commercial inkjet inks in an aqueous solution. The results were compared with their stability on prints in order to establish the connection between the kinetics of photodegradation of dye in the solution and the durability of the final print. Thin-layer chromatography (TLC), chromatography with a mass selective detector (GC/MS), and spectrophotometric measurements were used to study the effect of light, including near UV. The results clearly show that the catalytic effect between different dyes cannot be avoided, as the inks for inkjet printing are usually a mixture of different colorants. A comparison of the results of photodegradation of the dye in solution and on the final prints does not show a direct connection due to the different influences of external factors. Consequently, it was established that it is not possible to predict the photodegradation of prints solely based on a single dye’s analysis in solution. The paper as a substrate must be included in the analysis, as it significantly influences the photodegradation of the print.

During the lifespan, graphic products are exposed to various external factors. During their use, their properties(physical, mechanical, visual, etc.) change to a greater or lesser extent. It is necessary to observe/monitor changesand influence of external factors on their properties as soon as the product is created. The aim of this research is toexamine the impact of the aging process on the quality of inkjet printing. A different number of layers of black ink (in10 % tonal value (TV) and 100 % TV) and a different number of varnish layers were printed on PVC foil material. The samples were exposed to xenon light (λ > 300 nm) to accelerate the ageing process over a period of 72 and 216 h. They were measured by Datacolor spectrophotometer. As expected, with longer exposure time, greater changes occurred. According to the CIE ΔE*00 formula, the differences ranged from an imperceptible to a large colour change. After 72 h, the biggest changes in colour occurred in the K10 % with one ink layer and three layers of varnish. The smallest changes were in K100 % with one ink layer and no varnish. After 216 h, the greatest changes were observed in the K10 % sample with three layers of ink and two layers of varnish. The smallest differences were K10 % sample with one ink layer and without varnish.