For example: four-color printing machines or two-color printing machines are affected by the order of colors. In a layman's terms, it is the different order of colors used in printing, and the result printed is different. Sometimes the printing color sequence determines the beauty of a printed product.
Today, the editor will learn with you about the factors affecting the reasonable arrangement of printing color sequence and the principles that need to be followed.
The reason for arranging the printing color sequence 01
The main reasons for the need to arrange the printing color sequence are as follows:
The influence of ink mutual superposition and the shortcomings of ink pigments themselves
Quality of paper
Human eye's ability to recognize colors
The most fundamental reason is the incomplete transparency of the printing ink itself, that is, the covering power of the ink itself, and the ink printed later has a certain covering effect on the ink layer printed first, resulting in the colors presented by the printed matter always tending to express the later color, or rather, the mixed color of the later and earlier colors.
02 Factors affecting the printing color sequence
1. From the consideration of ink transparency
The transparency of ink is related to the hiding power of the pigment in the ink. The so-called hiding power of ink refers to the ability of the covering layer of ink to cover the underlying ink. Poor hiding power means strong transparency of the ink, and strong hiding power means poor transparency of the ink. Generally, the ink with poor hiding power, that is, strong transparency, should be printed later, so as not to cover the brilliance of the previous ink and facilitate the reproduction of colors. The relationship between the transparency of ink and the strength of the hiding power: Y>M>C>BK.
2. From the consideration of ink brightness
Print the ones with lower brightness first and the ones with higher brightness later, that is, print the ones with deeper ink first and the ones with lighter ink later. Because the higher the brightness, the higher the reflectivity, the more vivid the reflected color, and the slight misalignment of the light color on the dark color is not very conspicuous; while if the dark color is printed on the light color, it will be exposed. In general, the relationship between the brightness of the ink is: Y>C>M>BK.
3. From the perspective of ink drying speed
Print the slower-drying ink first and the faster-drying ink last. If the faster-drying ink is printed first, it is easy to become glassy for monochrome machines, which is not conducive to fixation; for multicolor machines, it is not only not conducive to the superposition of ink layers, but also prone to other defects, such as backside staining, etc. The order of ink drying speed: yellow is twice as fast as red, red is twice as fast as cyan, and black is the slowest.
4. From the nature of the paper
① Paper surface strength
The surface strength of paper refers to the结合 force between fibers and fibers, fibers and glue, and fillers on the surface of the paper. The greater the结合 force, the higher the surface strength. The degree of powder shedding and hair shedding on the paper surface is often used to measure it in printing. For papers with good surface strength, that is, with great结合 force, which are not easy to shed powder and hair, we should print the ink with greater viscosity first, and the ink with greater viscosity is also conducive to over印 when printed first.
② For paper with good brightness, it is better to print dark colors first and then light colors.
③ For rough and loose paper, print the light color first and then the dark color.
5. From the perspective of the market share of outlets
The dots with small area are printed first and the dots with large area are printed later. In this way, the printed image will be more colorful and the layers will be more distinct, and it is also beneficial to the reproduction of the dots.
6. From the characteristics of the original manuscript itself
Generally speaking, the original can be divided into warm tone original and cold tone original. For the original with warm tone as the main tone, it should be printed with black and cyan first, and then printed with magenta and yellow; for the original with cold tone as the main tone, it should be printed with magenta first, and then printed with black and cyan. In this way, the layers of the main tone can be more prominent.
7. From the perspective of mechanical properties
Since the models of the offset printing machines are different, their over印 methods and effects also have certain differences. We know that the single-color machine is the "wet-on-dry" form of overprinting, while the multi-color machine is a combination of "wet-on-wet" and "wet-on-dry" forms of overprinting, and their overprinting effects are also different. The usual color sequence for a single-color machine is: print yellow first, and then print magenta, cyan and black in turn.
03 Printing color sequence must follow the principles
The printing sequence will directly affect the quality of the printed product, in order to achieve a good reproduction effect, the following principles must be followed:
1. According to the lightness order of the three primary colors
The lightness of the three primary colors of ink is reflected in the spectrophotometric curve of the three primary colors of ink, the higher the reflectivity, the higher the brightness of the ink. Therefore, the lightness of the three primary colors of ink is: yellow > cyan > magenta > black.
2. Arrange the color sequence according to the transparency and coverage of the three primary color inks.
The transparency and coverage of ink depend on the difference in refractive index between the pigment and the vehicle. Inks with strong coverage have a greater impact on the color after overprinting, and it is not easy to show the correct color when printed as a post-printing overprint, which cannot achieve a good mixing effect. Therefore, inks with poor transparency are printed first, and inks with strong transparency are printed later.
3. Arrange the color sequence according to the size of the network area.
In general, the plates with smaller dot areas are printed first, and those with larger dot areas are printed later.
4. Arrange the color sequence according to the characteristics of the original manuscript.
Each original has different characteristics, some belonging to warm tones and some to cool tones. In the order of color sequence, those with warm tones are printed in black and cyan first, and then in red and yellow; those with cool tones are printed in red first, and then in cyan.
5. Arrange the color sequence according to the different equipment.
In general, the printing sequence of single-color or two-color machines should alternate between light and dark colors; for four-color printing machines, it is usually better to print the dark colors first and then the light colors.
6. Order of colors according to the nature of the paper
The smoothness, whiteness, tightness and surface strength of the paper are different, smooth and tight paper is printed with dark color first and then with light color; rough and loose paper is printed with bright yellow ink first and then with dark color, because yellow ink can cover the defects of paper such as paper hair and powder falling off.
7. Arrange the color sequence according to the drying performance of the ink.
Practice has proved that yellow ink is nearly twice as fast as magenta ink to dry, magenta ink is twice as fast as cyan ink, and black ink has the slowest fixation. The ink with slower drying speed should be printed first, and the ink with faster drying speed should be printed later. In order to prevent glassification, the single-color machine generally prints yellow last to allow the film to dry quickly.
8. According to the flat net and the color sequence of the field arrangement
When there are both flat and solid areas in the reproduction, in order to achieve good printing quality, to make the solid area flat, the ink color bright and thick, it is generally printed with flat area images first and then with solid area structures.
9. According to light and dark color sequence
To make the printed matter have a certain gloss, the light color is printed first, and then the dark color.
10. The area of the text and picture of the product is much larger than the magenta plate, according to the principle of printing the color plate with a large area of text and pictures behind, it is appropriate to use the order of black, magenta, cyan and yellow.
11. Products with text and solid black generally use the sequence of cyan, magenta, yellow, and black, but black text and patterns cannot be printed on solid yellow, otherwise, due to the low viscosity of yellow ink and the high viscosity of black ink, reverse printing occurs, resulting in black ink not being printed or printed firmly.
12. For small areas of four-color overprint, the sequence of printing can generally be arranged according to the principle of printing the color plate with larger area of text and images later.
13. Products of gold and silver color, due to the small adhesion of gold ink and silver ink, gold and silver ink should be placed as the last color as much as possible, and it is not advisable to use three-color over.
14. The printing color sequence should be as consistent as possible with the color sequence during the proofing process, otherwise it will be difficult to match the proofing effect.
If it is a 4-color machine, printing a 5-color job, you need to consider the problem of embossing or over印. Generally, the color of the bite position is more accurate in over printing. Also, if there is over printing, be sure to make a trap, otherwise the over printing will not be accurate and it is easy to miss white.
