Color prints cannot be separated from the overprint of four-color inks. The level of printing quality is closely related to the rate of ink overprinting. For example, the high rate of overprinting of ink appears thick and the color reproduction effect is good. Ink overprinting includes two conditions, namely "wet-press dry" and "wet-wet-wet". “Wet and dry†superimposition refers to the fact that when the monochromator prints, after the previous color is printed, it must be dried for a certain period of time to complete the oxidation conjunctiva on the surface of the ink. In the case that the printed sheets are not sticky, the next color printing can be performed. However, the drying time should not be too long (as long as the printed sheets are not sticky). Otherwise, not only the production efficiency is extremely low, the customer's delivery requirements cannot be met, and due to a long time, overprinting of the paper is not allowed. For "wet-wet-wet" printing, especially for multi-color or even multi-color double-sided printing, overprinting of color inks is of great importance for ensuring the printing effect. Drying time depends on the printing materials used, such as paper, ink, and the pH value, equipment used, graphic ink coverage and other factors. In particular, the drying properties of different substrates vary greatly. In addition, when the pH is too low (eg, less than 4.5), the ink film drying time is significantly prolonged. When the pH value decreased from 5.6 to 2.4, the drying time of the ink film was extended from the original 6 hours to 24 hours. The determination of the stacking drying time is very important to prevent printing failures and ensure print quality.
When using a multi-color offset printing machine, the printing interval between each color is very short, the ink just printed on the front will be superimposed on the new ink in a very short time, and the ink film will adhere to each other in a wet state. For "wet pressed wet" printing. "Wet-wet-wet" printing has a different amount of ink transfer than "wet-press-dry" printing, and the "wet-wet-wet" printing ink has a lower trap rate than a "wet-pressed" printing ink. On the other hand, “wet-wet-wet†printing has a key problem. It is closely related to the color sequence of color ink printing. That is, the viscosity of the previous color ink must be greater than the viscosity of the latter color ink in multicolor printing, otherwise the first printing ink The film will be stripped by the printed ink film, resulting in an inverse overprint. The drying of four-color inks that are instantly combined together is similar to the type of the substrate, the type of ink, and the pH of the fountain solution. The size of the ink overprint also depends on the drying capacity of the printing press drying system (infrared drying, dusting, and layering).
Source: "Printing World"
Author: Yin Ping
When using a multi-color offset printing machine, the printing interval between each color is very short, the ink just printed on the front will be superimposed on the new ink in a very short time, and the ink film will adhere to each other in a wet state. For "wet pressed wet" printing. "Wet-wet-wet" printing has a different amount of ink transfer than "wet-press-dry" printing, and the "wet-wet-wet" printing ink has a lower trap rate than a "wet-pressed" printing ink. On the other hand, “wet-wet-wet†printing has a key problem. It is closely related to the color sequence of color ink printing. That is, the viscosity of the previous color ink must be greater than the viscosity of the latter color ink in multicolor printing, otherwise the first printing ink The film will be stripped by the printed ink film, resulting in an inverse overprint. The drying of four-color inks that are instantly combined together is similar to the type of the substrate, the type of ink, and the pH of the fountain solution. The size of the ink overprint also depends on the drying capacity of the printing press drying system (infrared drying, dusting, and layering).
Source: "Printing World"
Author: Yin Ping
Vicarb Related,Heat Exchange Plates,Plate,Vicarb Plate
6Z Heat Exchanger Manufacturing Co., Ltd. , http://www.jialong-coolers.com