Multi-color Overprinting How to Correctly Arrange Color Sequences

In the offset printing process, the correct selection of the color sequence is a key link for overprinting four-color inks. Incorrect color ordering will have a great impact on the product. In the actual production, there are often cases where the printed product is scrapped due to incorrect color sequence. Let's talk about some issues that should be noted in the color sequence arrangement of the printing process. First, the color sequence of a single-color offset press We usually say: (yellow) Y, (magenta) M, (blue) C, (black) K is the color sequence, multi-color superimposition of monochrome offset press is generally used Shun sequence. This color sequence is based on the size of the ink's transparency. First, the ink with the lowest transparency is printed in the first color, and then the ink with high transparency is printed. The common color sequence for a monochrome offset press is based on the viscosity of the ink. The yellow ink with low viscosity is printed first to prevent the back of the printed material from getting dirty. Only then ink with increasing viscosity was printed. Also take into account the depth of the color of the ink, the printing process, the light color of the ink is printed first, and then gradually dark ink color printing. In this way, it is much easier to clean the ink roller and ink tank when printing the next color when changing the ink color. Because the color sequence is printed on the yellow plate first, people's naked eyes are not easy to observe on the yellow dot, and the yellow plate is slightly overprinted in the printing process. This is the defect of using the color sequence. The monochrome color offset printing machine does not use the color sequential sequence for multicolor superimposed color arrays. According to different manuscripts and different quality requirements of customers, color sequencing should be properly adjusted to avoid stereotyped practices. Second, the multi-color offset printing machine color sequence arrangement and monochrome offset press "wet stack dry" printing method is different, multi-color offset printing press is "wet wet." That is, when the surface of the ink is not completely dry, the other ink is overprinted. The color sequence arrangement of multi-color offset printing machines mostly uses inverted color sequences, namely black, blue, red, and yellow. Multi-color offset printing machine mainly considers the ink viscosity, the viscosity of the commonly used four-color ink, followed by K> C> M> Y, multi-color offset press color sequence is gradually higher by the ink viscosity in the end. That is, high-viscosity inks are printed on the front side and low on the back side, so that the laminated fastness is better. We know that the viscosity of the ink has a great influence on the superficial fastness. Ink transfer depends on the effect of pressure, because there is a cohesive effect between different color inks, the result must be the same color is pulled out by another color, and the key to determine who and who pulled the color between the key is the viscosity of the ink size. The cohesive force of the ink with a large viscosity is large, and at the instant of superimposition, the ink with a lower viscosity is pulled out due to a greater cohesive force of its own. Therefore, the ink with the larger viscosity is printed first, and the color fastness is large, and the overprint effect of the printed product is better. Multi-color offset presses do not take this into account when orchestrating the color sequence, which can result in overlapping colors that cannot be performed. The electronic color separation machine adopts the UCR method to appropriately reduce the color ink amount in the composite color areas of Y, M, and C in the printed matter, and replaces the color ink with black ink. This new process is not only conducive to high-speed overprint, reduce costs, but also conducive to the balance of neutral gray, improve the quality of overprint products. Things are always relative. The color sequence of a multi-color offset press is not immutable. The reproduction of tone levels is a very detailed task. Specific issues must be analyzed. During the actual production process, various types of manuscripts will be touched. For example, the manuscripts of the Guilin Lijiang River and the vast sea reflecting natural scenery are mainly blue, and the color sequence can be black, red, blue, and yellow. , so that it fully shows the blue bright and broad. This type is mainly to master the blue version, other color attention leveling tone on the line; such as the character screen, the focus is the human face color, this type of manuscript is mainly red and yellow, color sequence can be blue, black, red The yellow, blue, and black editions are parts of the hair and eyes, lines, etc. The emphasis is on the skin color and expression of the red and yellow highlights. The color sequence of a multicolor offset press should also consider transparency. The lowest transparency of the first printing, the color sequence for the K, C, M, Y, black ink, the lowest transparency, that is, the darkest, as the outline of the screen with a darker color, it should be placed in the front printing. Transparency is an important indicator of ink. Putting high transparency on the final print can make the entire screen colorful and eye-catching. The reason for this is that the color rendering mechanism of the printed matter is to use color-reduced light as the additive color reproduction of the primary color light, and finally printed on it. First of all, it is in contact with the outside world. The ink with high light transmittance can be reflected more strongly into the ink in the lower layer. , And then reflected by the paper to show its own color, if the final printed on the transparency is low, large light blocking, will inevitably affect the color of the other color ink. In fact, the ink used for printing is not absolutely transparent, and they are all slightly opaque. Therefore, the transparency of various inks should be carefully compared when printing. Three, commonly used four-color ink can be arranged in the multi-color overprinting 24 color sequence: K, M, C, YM, C, K, YK, M, Y, CM, C, Y, KK, C, M, YM , K, Y, CK, C, Y, MM, K, C, YK, Y, M, CM, Y, K, CK, Y, C, MM, Y, C, KC, Y, M, KY, K , M, CC, Y, K, MY, K, C, MC, M, Y, KY, M, K, CC, M, K, YY, M, C, KC, K, Y, MY, C, K , MC, K, M, YY, C, M, K More than 24 color sequences can be selected by the multi-color printing press. Among them, the best and the worst are to be determined according to the actual situation. When we consider the color sequence, we must first analyze and study the features of the manuscript and the properties of the used plates. Secondly, we must make a comprehensive evaluation of the printing methods, quality requirements, printing materials, printing suitability, and ink color equality, and then combine them. This company's specific situation, set an appropriate color order. In addition, there are two variable factors that can not be ignored when determining the color sequence: 1. The color cast problem of several inks after overprinting M, C, Y is easy to be green after the overprint, and C, M, Y are easily reddish after overprinting, C , Y, M is easy to reddish after overprinting, M, Y, C is brownish green after overprinting, Y, C, M are overprinted after light violet, and Y, M, and C are overprinted after blue and green. 2. Lightfastness and Heat Resistance of Printed Products If the products we are printing on are advertised in outdoor advertising posters, posters, and New Year's pictures, these products are exposed to the direct sunlight and are exposed to ultraviolet light for a long time. Wind and rain, bright colors tend to fade, and in the end there may be only black and blue inks, both red and yellow will fade. Therefore, in order to reduce the fading phenomenon, it is better to print the Y and M colors firstly and the C and K colors after the exposure of such exposed outdoor prints. In this way, the last two colors C and K have good heat resistance and heat resistance. Reduce the fading of prints and maintain multiple colors of prints.