CORRELATION OF INK PENETRATION WITHIN THE PRINTING SUBSTRATE AND PRINT-THROUGH EFFECTS IN OFFSET, GRAVURE AND SCREEN SUSTAINABLE PRINTS

The drying process of printing ink on absorbent substrates in conventional printing techniques essentially takes place in two steps: the penetration of the ink within the printing substrate and the oxidation or oxy-polymerization process. The process of ink penetration within the printing substrate itself begins immediately after the ink is transferred using the impression cylinder, while the oxidation or oxy- polymerization process lasts up to several hours. In this research, the correlation between the value of ink penetration within the printing substrate and the print-through effect on prints produced using three different printing techniques was observed. In this analysis prints made on sustainable printing substrates were produced with a 30% share of non-wood cellulose pulp were observed in order to reduce the consumption of wood raw materials worldwide. The results of the research prove that the degree of ink penetration within the printing substrate correlates with the print-through effect in all analysed black prints (printed with one ink layer), while no correlation was found in the prints that were printed with three ink layers (cyan, magenta and yellow). That is the print-through effect is very low compared to the values obtained for ink penetration within the printing substrate. It was also found that the lowest values for ink penetration inside the printing substrate was achieved with offset printing process, and thus the lowest values for the print-through effect. Sustainable printing substrates achieve very low deviations compared to reference substrates made only from recycled wood pulp, which confirms the possibility of using these substrates for both secondary packaging and publications.