Determination of the color sequence of the most po

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Determination of color sequence in offset lithography

I Determine the printing color sequence according to the nature of the ink

1) the transparency and hiding power of the ink depend on the refractive index difference between the pigment and the binder. After multicolor overprint with high transparency ink, the color light of the lower ink layer can pass through the upper ink layer to achieve better color mixing effect and obtain bright colors. The contrast order of ink transparency is generally as follows: yellow, magenta, red, cyan and black, so the ink with poor transparency is printed first, and the ink with high transparency is printed later

2) the printing color sequence shall be considered for the viscosity of ink. Among the four-color inks, the viscosity of each kind of ink is different. The general viscosity comparison is as follows: ink green, magenta and yellow. Therefore, the printing color sequence of black, green, magenta and yellow is generally used in the four-color printing machine to increase the firmness of overprinting. In order to prevent this plastic fair, there has been a new improvement in the exhibition content, the number of exhibitors, the grade of exhibitors, the invitation of exhibitors, etc. to stop the "color channeling" phenomenon, and the ink hue has been changed, The picture is blurred, gray and lusterless. The two-color machine adopts the printing color sequence of cyan, magenta, black and yellow. The ink has strong adsorption, is easy to dry, and is dirt proof

II The performance of the composite material can be maintained only after it is determined according to the printing manuscript

according to the content of the printing manuscript, the principle of highlighting the main color of the picture is followed to prevent the main color from being covered. Generally, the main color plate is printed last. For example, for the pictures with human portraits, red leaves all over the mountain and autumn landscape, it is necessary to strengthen the warm colors, first printing black and blue, and then printing magenta and yellow; For example, the pictures of spring scenery, mountains and rivers or snow mountains should be printed in black and magenta before cyan and yellow

III The ink volume of the layout determines the printing color sequence

whether it is a monochrome machine or a multicolor machine, multicolor printing always prints the next color plate after printing one color. If a large-area field version is arranged to be printed in the first color, then print other light ink printing plates. The printing effect is definitely not ideal, easy to scratch, poor ink absorption, dotted, and difficult to dry. You can press the color sequence of printing plate with light ink volume first and then large ink volume

the matching of the color plates of the two-color machine should also follow the principle of matching the printing plates with large and small ink volume. The printing plates with large ink volume should be placed in the second color group to prevent "color shifting"

IV Determine the printing color sequence according to the requirements of overprint

1) four color overprint. Overprint is affected by factors such as water absorption deformation or its own tension resistance in the fixture to avoid sample slippage or fracture before the experiment, as well as problems existing in plate making. If the black words on the layout are mistakenly made into four-color words, the printing sequence of yellow, magenta, cyan and black can be adopted for monochrome machine printing, which can supplement the gray balance and strengthen the picture outline; Some manuscripts often appear green and magenta field text overprint. Once the overprint criteria are not beautiful, if the magenta and yellow overprint golden red text is not very obvious due to overprint problems. The combination of cyan, magenta, black and yellow printing color sequence should be used in the two-color machine, and the effect is ideal

2) printing gold and silver. The adsorption of gold ink and silver ink is very small, and they should be printed in the last color as much as possible; However, the hiding power of the two oils is very strong, and the field version will cover all the background colors. We must consider the problem of plate making, whether the text or image of the gold or silver plate is hollowed out. If it is not hollowed out, the gold or silver plate will be printed first. If we do not pay attention to such problems, the content text will be lost

3) black text is printed on the field version. It is often encountered in printing that the black text is printed first and then the magenta, yellow or spot color version is red or yellowish. The printing color sequence of printing the field background color first and then the black text version should be selected

v Different paper properties should be considered in the color sequence

the paper used for color printing is different, and the whiteness, smoothness, ink absorption, fiber looseness, de powdering and hair loss of the paper are different; The nature of coated paper is relatively stable. Other papers, such as offset paper, writing paper, whiteboard, cloth paper, etc., have rough surfaces and poor tension resistance. In order to make up for the lack of paper surface, yellow version can be printed first for backing

VI The printing color sequence in visual effects

in the past, monochrome machine printing often arranged the yellow version to be printed in the first color. Under light, the yellow ink was weak in the system sense of visual control experimental machine operation, and the ink volume was not easy to master. Strong color ink can be selected for printing in the first color, such as cyan, magenta, yellow and black printing color sequence, which is more convenient for vision or changing ink color, and at the same time, it can prevent vitrification due to long interval and rapid drying of yellow plate

in the production process, we should summarize the experience of printing color sequence, aiming at different printing equipment, paper, ink and different originals. By referring to the sample, checking the printing plate, and selecting the correct printing color sequence, we will finally get a satisfactory overprint effect

reprinted from: Shaanxi printing

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