On the characteristics of spot color and four-colo

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Analysis on the characteristics of spot color and four-color printing process

1 What is four-color printing

four color printing process generally refers to the printing process that uses yellow, magenta, cyan primary ink and black ink to copy various colors of color originals

2. What is spot color printing

spot color printing refers to the use of yellow, magenta and cyan. A printing process in which the color of the original is reproduced with inks other than black ink and four-color ink. Spot color printing process is often used in packaging printing to print a large area of background color

3. What products must use four-color printing process

photos taken by means of color photography that reflect the rich and colorful color changes in nature, painters' color art works or other pictures containing many different colors must be scanned and separated by electronic color separation machine or color desktop system for technological requirements or economic benefits, and then copied by four-color printing process

4. What kind of products will use spot color printing

the cover of packaged products or books and periodicals is often composed of uniform color blocks of different colors or regular gradual color blocks and words. These color blocks and words can be separated and overprinted with four primary colors of ink, or they can be mixed with spot color ink, and then only a certain spot color ink can be printed at the same color block. Under the condition of comprehensively considering improving printing quality and saving overprint times, spot color printing is sometimes used

5. What is the difference between the color visual effect of spot color printing and that of four-color superimposed printing

the ink prepared by spot color printing obtains the color according to the mixing principle of color subtraction method. Its color lightness is low and its saturation is high: spot color blocks with uniform ink color are usually printed on the spot, and the amount of ink should be appropriately increased. When the thickness of the ink layer of the layout is large, the sensitivity of the change of the thickness of the ink layer to the change of color will be reduced, so it is easier to obtain the printing effect of uniform and thick ink color

for the color block printed by the four-color printing process, since most of the colors constituting the color block are composed of a certain proportion of points, the thickness of the ink layer must be strictly controlled when printing points, and it is easy to change the color intensity due to the change of the thickness of the ink layer and the change of the printing process conditions. Changes in the degree of dot enlargement This causes the color to change. Moreover, because the change of any color constituting the color block will lead to the change of the color of the color block, and the chance of uneven ink color will be doubled, it is not easy to obtain the effect of uniform ink color for the color block overprinted by the four-color printing process. If you can't use a multicolor machine to print the color of the color block at one time It is also prone to color deviation because the color of semi-finished products is not easy to control. In addition, four-color printing obtains the comprehensive effect of subtractive absorption and additive mixing of dots, with high brightness and low saturation of color blocks. For the light color block, the four-color printing process is adopted. Due to the low coverage of the ink on the paper, the ink color is flat and lacks a thick feeling. Due to the point angle, people will inevitably feel the existence of patterns

6. From the perspective of improving product quality, what kind of products are suitable for spot color printing

when printing large areas of light and uniform color blocks, it is usually used to add: medium light agent to the original ink to prepare the spot color ink, and then carry out field printing, so that the ink layer is thicker, and it is easier to get the effect of uniform and thick color. If a four-color printing process is used, a low percentage of flat dots must be used. Shanghai printing, but a low percentage of flat spots are easy to be reduced by small sand particles or slightly poor air extraction when printing, resulting in uneven ink color: when printing, it is easy to supply too much water for the layout. The paper powder accumulates on the printing plate and blanket, and the low smoothness of the paper causes poor ink transfer of small dots. Thus, the ink becomes lighter and the ink is uneven

for dark large-area color blocks, the four-color printing process may need to be formed by the superposition of high salty points of several colors, and the ink layer is too thick, which is easy to get dirty on the back; The spot color printing process only needs to print one color, which is not easy to get dirty on the back. Using four-color printing process, some parts of the picture and text may be composed of several colors; By using spot color printing technology, only one color is printed on the corresponding part, which avoids the possibility of overprint error

7. From the perspective of economic benefits, what kind of products are suitable for spot color printing

from the perspective of economic benefits, it mainly depends on whether the spot color printing process can save the number of overprint. Because reducing the number of overprint can not only save printing costs, but also save the cost of prepress production

8. Can a product be printed in four colors and spot colors at the same time

if the picture of a product has both a color layered picture and a large area of ground color, the part of the color layered picture can be printed in four colors, and the large area of ground color can be printed in spot color. The advantage of doing this is that the four-color printing part can correctly restore the picture by controlling the field density, and one steel ball on the bottom rotates against three static steel balls below. The color part can obtain the visual effect of uniform and thick ink color by appropriately increasing the ink volume. This method is often used during the "1025" period of high-end packaging products and the printing production of stamps, but due to the increase of color number, the cost of printing and plate making also increases

9. When using the four-color printing process, if there is a large area of black field, how can plate making be more conducive to the thick black field ink

when using the four-color printing process, in order to ensure the correct printing of the order and color, the output medium temperature, pulse times and pulse pressure waveform; Restore, the ink layer thickness of each color should be strictly controlled. Generally, in four-color printing, the density of black field is no more than 1.8. Printing a large area of black field with such density will lack thick visual effect. The commonly used force method is to overprint about 40% of the cyan on a large area of black field

black field overprint a small amount of cyan. From the hue, it is still black, but the visual effect will be thicker. Originally, when only one color black was printed on white paper, due to the paper wool in the printing process. The accumulation of paper powder on the rubber blanket, or the transfer of ink due to other reasons, resulting in the scratch of the jaw seat slope, will make white sand holes appear on the black field, and the black-and-white contrast is very conspicuous. If the cyan flat is overprinted, even if there are a few sand holes on the black field, because the exposed point is no longer a white paper base, but a cyan point, compared with the black-and-white contrast, the black-and-green contrast is less conspicuous, which can make the black background look more uniform and beautiful

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