A Study of Dot Gain and Gamut for Prints Made with Highly Pigmented Inks

The technology of the used machines and tools in printing technology and in the offset printing has reached the stage when, technologically, it is very difficult to raise the printing quality with the up to now used production materials, which the world market demands more and more [1, 2]. Because of that the producers of the printing materials and inks invest great means in the development of materials which would enable increasing the printing quality [3, 4]. One of the main ways of increasing the printing quality today is the development of the new highly pigmented inks, which contrary to the inks used up to now, have the increased ability to cover the printing elements [5]. One of the main quality limitations of the printing made with classical inks was the impossibility of the ink to adhere qualitatively to paper i.e. to the printing substrate, when it is above the critical point of the ink layer thickness above 2 μm [3, 6]. The critical point of the ink layer thickness occurs in the moment when the ink cannot qualitatively adhere to the paper, i.e. when there is not enough absorption into paper or not enough drying of ink. In such situations the ink stays wet on the print and the undesired consequences occur. The mentioned consequences can be such that the ink offsets on the other side of the paper it is in contact with. The rubbing, i.e. removing of ink caused by the mechanical manipulations with prints can also occur. The main advantage of the highly pigmented inks is in the fact that better inking is achieved with the standard thickness of the ink layer. Because of that the research of the printing quality increase was performed with highly pigmented inks on two most often used papers in the sheet fed offset printing, so