In the offset printing process, the correct choice of printing color sequence according to certain principles is the key to improving the quality of printed matter.
1. The color sequence arrangement of a single color offset press We will use the Y, M, C, and K color sequence superimposition as the color sequence. Under most circumstances, most color offset presses can use the color sequential printing. Color sequential printing is the printing of the ink with the lowest transparency in the first color, and then overprinting with the higher transparency of the ink, that is, in order of the transparency of the ink to arrange the printing.
The monolithic offset press is wet-stacked. The color sequence of a monochrome offset press therefore places the viscosity of the ink in a less important position.
In addition, from the perspective of the color of the ink, the single-color offset press is printed in the order of Y, M, C, and K, which is advantageous for color change and easy cleaning of the ink roller and ink tank.
Another reason why a monochrome offset press prints a yellow version is that human vision is insensitive to yellow dots, and even if a pale yellow color is printed, even if it is slightly overprinted, it is not easily visible to the naked eye. It is conducive to the accuracy of four-color overprinting.
The wet and dry printing method of a monochrome offset press should also take into consideration the lightfastness and acid and alkali resistance of the ink. Monochrome machine adopts color sequence Y, M, C, K printing, printing saturation, light resistance, heat resistance, acid and alkali resistant and strong alcohol resistant magenta and cyan printing on the back, will help improve print quality.
The overprinting sequence of the monochrome offset press is not immutable. It is necessary to correctly adjust the color sequence according to the originals, printing materials and models, and to avoid stereotyped old frames and old sets.
2. The color sequence arrangement of a multi-color offset press The color sequence of a multi-color offset press mostly uses the inverted color sequence, namely K, C, M, Y. Multi-color printers are wet and wet, meaning that the ink is superimposed on another ink in a very short time without drying the oxidized conjunctiva. The second color printing by the two-color offset printing press can be said to be wet and wet, and in the third and fourth printing overprinting, there are a plurality of superimposition printing modes simultaneously performed by wet pressure drying and wet pressing. Therefore, due to the different types of models, multi-color offset printing press color sequence arrangement and monochrome machine is different. The color sequence of a multi-color offset printing press is arranged according to the viscosity of the ink, and the ink with high viscosity is printed on the front side. In this case, the over-printing fastness will be better, and the “bleeding†will not be caused by the size of the viscosity. As a result, the printed product has a blurred picture, dark color mixture, and poor gloss. However, the effect of ink overprinting cannot be attributed entirely to the ink viscosity, but it should be said that the ink viscosity and the amount of ink play a role. Therefore, in order to achieve a good overprint effect, the ink should have the following points:
1. The ink should have the proper viscosity and concentration.
2. When wet wet printing, it is necessary to have moderate ink supply, too much and too little are not good.
3, ink requires positive hue, high transparency, good gloss, fine ink particles, acid and alkali, good chemical stability.
Wet wet printing should first understand the effect of ink viscosity on the fastness of overprinting. The transfer of ink from the printing plate to the paper relies on the effect of the printing pressure, and the ink with a large viscosity adheres to the ink film with low viscosity due to its cohesive force. If a multicolor offset press does not take this into account when formatting the color sequence, overprinting cannot be performed.