How to control the color sequence flow of offset p

2022-08-01
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How to control the printing color sequence flow of offset printing

color reproduction printing uses the dots of yellow, magenta, cyan and black at different angles for plate making and printing. In this way, the combination form of four-color dots transferred to white paper is; In the bright part of the picture, each color point is always in the form of parallel combination; The color dots of the middle tone part are the combination of most of them and a small part of them; The various color points of the dark part are almost completely superimposed

printing color sequence and ink characteristics

from the point color rendering principle, whether it is point superposition or point juxtaposition, it belongs to the color rendering principle of color subtraction method. As far as the color sequence of multi-color printing is concerned, no matter what kind of printing color sequence is adopted, it will not have any impact on the color restoration of the bright part of the color image, but the middle and dark tones are affected, because these two parts are colored by point superposition. Ink has different degrees of covering, even transparent yellow. For example, if transparent yellow is printed on the silver white aluminum foil, the silver white aluminum foil will turn yellow. Similarly, the color of the ink film first printed on the white paper can not be completely displayed after it is covered by the later printed ink film, and the later printed ink can be fully colored, which is the inevitable law of multi-color overprint

another factor that affects the tone restoration of color images is that the first color ink printed in the wet press wet printing state, when overprinting the second color, the third color and the fourth color, is stuck away by the rubber roller in turn, so that the "speed of going to the sea" is extremely highlighted on the fourth color rubber roller, showing a four-color color image. The third color ink is less adhered, and only the fourth color ink is 100% retained. It can be seen that the third color and the fourth color are extremely critical in the order of increasing demand for carbon fiber in the printing color Boeing b777x and the next generation aircraft body. Practice has proved that even if all printing conditions are the same and only the printing color sequence is different, the color effect of printed matter will be different

arrangement rule of printing color sequence

as far as four-color printing is concerned, the printing color sequence can be combined into 24 modes according to mathematical arrangement. If light color or spot color is added, the combination of printing color sequence will be more. However, the most commonly used printing color sequence in actual production is only shown in

the general arrangement of printing color sequence follows the following rules:

(1) convenient color change

(2) the ink with poor transparency and strong hiding power is placed in the first color printing

(3) put black on the first color print for accurate overprint

(4) the color with small ink volume shall be printed first, and the color with large ink volume shall be printed later

(5) back printing with transparent ink

(6) when the smoothness of the paper is poor, the ink with coarse pigment particles is placed in the first color printing

(7) when the paper tightness is poor, the light color shall be printed first

(8) in order to increase the gloss of the picture color, light color can also be post printed

(9) in the warm and wet state, yellow is placed in the fourth color (such as the four-color machine color sequence) because other inks have poor adhesion to yellow ink

the above factors are mainly considered from the aspects of paper, ink and convenient color change, and less consideration is given to tone restoration. In fact, there are three standards to measure the quality of offset color printing: first, tone restoration, second, tone restoration, and third, overprint accuracy (i.e., high image definition). Besides the close relationship with plate making, hue restoration is also related to printing color sequence

arrange the printing color sequence by tone

manuscript is the first of the five elements of printing, which is not only the basis for plate making, but also the basis for printing. That is, the proofing printing color sequence must be based on the original color tone, and the printing color sequence must be consistent with the proofing color sequence. Although there are many kinds of originals and different colors, the picture of any color original has its primary color (the dominant color), while other colors are secondary colors (the background color). Therefore, when matching colors (printing color sequence is also a kind of color matching), we must follow the principle of master-slave. If the main tone cannot be fully displayed on the printed matter, and the subordinate tone is highlighted, it will lead to the inversion of the main and subordinate tone, which will not only make the printed matter tone unable to be restored, but also destroy the atmosphere of the whole picture and affect the theme of the work

although the colors of the original are diverse, from the perspective of the total color of any picture, it tends either to warm colors (yellow, orange, red, etc.) or to cold colors (green, blue, purple, etc.). Green is a neutral color, a mixture of yellow and green, between warm and cold. Yellowish green belongs to warm tone, while cyan green belongs to cold tone, and neutral tone is rare

the main advantage of this arrangement of color sequence according to cold, warm and neutral tones is that the decisive color is arranged in the last two most critical colors, especially yellow or cyan in the fourth color. It can be seen from table 3 that the important purpose of yellow and cyan is to increase the important role of equipment wear

this printing color sequence based on the combination of cold and warm tones has the following advantages:

(1) it meets the requirements of any tone original, is easy to restore the tone, and can ensure the color consistency of the printed matter

(2) it makes up for the insufficient hiding power of the current ink, and can better highlight the main color of the picture. It is also suitable for FM and am plate making process, four-color plate making process at the same angle, three-color plate making process and color structure process

(3) put the black ink with the greatest covering power in the first color sequence, which is conducive to accurate overprint of other color plates and clear images

(4) the machine operator is easy to master and control the ink color

but there are also some problems: in the wet press state, the adhesion of the post printing ink is very small when the yellow ink is not dry. Therefore, the yellow ink must change its performance, otherwise the cold tone printing color sequence cannot be used on the four-color machine. The local color machine and the two-color machine, which only contribute to the dispersion, extensive, environmental pollution, disorderly export, and are difficult to be regulated, do not have such a problem because they are wet press dry. Although the color sequence of cold and warm tone printing is applicable to the current four-color plate making process, it brings great resistance to the study of non-color structure process. People very much hope to obtain ideal black ink with high blackness and good gloss, but in reality, absolute black does not exist, and there can only be relative black. One of the problems encountered in the research of the new process of achromatic structure is that the dark tone of the sample is not enough and the gloss is poor. In fact, this is also closely related to the printing color sequence. Because the bright three primary color inks have a certain degree of hiding power, especially magenta ink and yellow ink. No matter which kind of overprint is on the black ink, it will affect its blackness and gloss. If a small amount of green ink is overprinted on the black ink, it can increase the black effect, which is a problem of visual perception

for some originals with a large area of black as the main dark tone and those with a large area of black as the background, if the printing plate is made by the non color structure process

this kind of printing color sequence is ideal, which can not only make the blackness of black ink unaffected, but also solve the problem of hue. The ink amount of the black plate with non color structure is generally greater than that of the color ink. The black plate with large ink amount is completely suitable for printing suitability at the end

printing color sequence of traditional Chinese ink painting

traditional Chinese painting is one of China's traditional plastic arts. Like using color, ink in traditional Chinese painting can make the scenery in the painting rich in color. Therefore, in traditional theory, the ink color of traditional Chinese painting can be divided into five colors: coke, thick, heavy, light and clear. Therefore, when copying and printing traditional Chinese ink painting, the plate making process of "one gray and one black" is often used. If there is burnt ink in the ink painting, The plate making process of "one gray and two black" must be adopted. The ideal color sequence in printing is shown in Table 5. If the printing color sequence of "one gray and two black" is changed, the level will be flat, and the coke ink will be adjusted to thick black

when painting, traditional Chinese painters often use techniques such as "thick breaking light" and "light breaking thick". In order to better display this technique, the printing color sequence shown in Table 5 should not be used, but the printing color sequence shown in Table 6 should be used

if the techniques of "light breaking thick" and "thick breaking light" appear at the same time in a picture, it depends on which one is dominant. In a word, the printing color sequence of traditional Chinese painting must be based on the sequence of pen and ink used by painters when painting, so that offset prints can fully show the artistic effect of "colorful ink" and "moving ink". For example, the printing color sequence of the "rongbaozhai" woodcut watermark in Beijing is completely carried out in accordance with the sequence of pens and inks when Chinese painters paint, thus achieving a state of superb craftsmanship and confusing the fake with the real

to sum up, when arranging the printing color sequence, we should not only consider the performance of ink and paper, printing suitability and other factors, but also comprehensively consider the color, art and process based on the original, so as to obtain the ideal printing color sequence. (by Liu Yuxiang)

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