[Summary]: [Experience] University Questions in Printing: Arrangement of Color Order

[Extended]: On the printing color sequence of different printing machines

[Extended]: Analysis of the color sequence of self-adhesive printing

[Extended]: 14 principles that need attention when arranging printing color sequence

Today, multi-color printing has occupied a dominant position in the printing industry. When we use a four-color printing press for production, how should we arrange the printing color sequence? Bisheng editor combined his own practical experience, summarized as follows.

1. Ink factor

Four-color machines generally use a printing color sequence in which the thickness of the ink film gradually increases. For example: C ink density is 1.6, the ink film thickness on paper is about 0.85μm; M ink density is 1.4, ink film thickness is about 0.9μm; Y ink density is 1.0, ink film thickness is about 1.3μm. If printing in CMY color sequence, the overprint effect is good. If the printing color sequence is changed to CYM, the ink film thickness is 0.85 μm, 1.3 μm, and 0.9 μm, respectively, resulting in poor M-color overprinting effect. Although the thickness of the ink film can be increased to improve the overprinting effect by increasing the amount of M ink, but after the thickness of the ink film exceeds 1.2 μm, the dots increase and color shift occurs.

When the density of C ink is 1.6, the thickness of the ink film is 0.85μm. If the density drops to 1.5, the thickness of the ink film is about 0.7μm. This is the lowest value that the ink can cover the paper when printing on coated paper, which is lower than this density value. , The printing field will be poor. So when encountering this kind of problem, it is better to dilute the ink so that the thickness of the printed ink film reaches 0.7 μm or more. Of course, when the thickness of the ink film exceeds 1.4 μm, in addition to the increase of the dots, it is also easy to produce undesirable phenomena such as backside smearing or reverse overprinting. It can be seen that the ink density has a great relationship, and it is necessary to fully understand the relationship between the ink film thickness and the ink density when printing.

Four-color printing belongs to wet press wet overprinting, and the post-printing color is easy to reverse sticking, so considering the viscosity of the ink, it is best to print according to the order of decreasing viscosity of the ink. In addition, in terms of the transparency of the ink, the printing color sequence with increasing transparency is preferred.

If the four-color printing is mainly based on the K version, the background color removal is done deeper. From the perspective of reverse overprinting, the best printing color sequence is CMYK. However, if the K version is a complementary color version, KCMY can be selected for the printing color sequence, which can save costs from another perspective. However, if the K version has too much ink, it will cause ink smearing in the latter color printing, which must be paid attention to.

2. Product features

There are many types of color printing, each with its own characteristics. Therefore, we must arrange the printing color sequence according to the characteristics of the product itself.

For newspaper printing, color newspapers are printed on newsprint paper that is porous, easily deformed, and low in whiteness. Overprinting is difficult on high-speed rotary offset presses, and the color reproducibility is inferior to offset paper and bond paper. The national standard "Requirements and Inspection Methods of Newspaper Printing Quality" stipulates that: the printing quality of color pictures basically conforms to natural tones, and four-color overprinting is accurate. Therefore, in addition to considering the effect of ink overprinting, the printing color sequence of color newspapers must also meet the requirements for overprinting and color reproduction of newspaper color pictures in the national standard. For example: The Zhoukou Daily, a party newspaper of our city, printed and printed by this newspaper agency, one of which contains mostly pictures of people. Therefore, after comprehensive consideration of various factors, we adopted the CMYK printing color sequence, which not only ensures a good overprint effect, but also does not produce cross-inking phenomenon under high-speed printing.

When copying prints or high-end artworks, they should be printed in strict accordance with the color order of the originals to better faithfully copy the originals. When printing a ticket, the shading should be printed before the border. When printing certain packaging prints, the main text or screen should be kept clear and not covered by other ink colors. Therefore, the main color sequence of the main text or screen of post-printing should be adopted.

3. Overprint accuracy

During the printing process of the paper, a certain degree of deformation and extension will occur through the rolling of the cylinder and the effect of the fountain solution, which will inevitably affect the accuracy of the overprint of the printed product. From the analysis of overprint accuracy, how should the printing color sequence be selected to better ensure the registration of printed products?

First of all, ink colors with low registration accuracy requirements should be printed first, and ink colors with high registration accuracy requirements after printing, so that the paper will gradually stabilize after the first two colors are printed, which can reduce the inaccuracy of the overprint registration. Secondly, the color or dark version with a small area should be printed first, and then the color or light version with a large area should be printed, so that even if the paper is deformed to a certain extent at the beginning, it will have little effect on the overprint of the printed product.

The color sequence arrangement of four-color printing should be analyzed according to specific situations and adjusted according to the actual situation at any time to achieve the best combination of printing quality, printing cost and printing operation.

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