Color deviation: refers to the color difference between the printed product and the original or proofing.

There are two reasons to prevent color deviation in process technology. (1) arrangement of screen cable angle for plate making. (2) arrangement of printing color sequence.Preventive Measures For Color Deviation Of Printed Matter

1： Arrangement of screen angle in color plate making

In the process of color plate making, if the arrangement of screen line angle is incorrect, it will affect the printing color effect, and moire will occur in serious cases.Preventive Measures For Color Deviation Of Printed Matter

At present, the four-color plate making and printing is mainly based on the three primary colors of yellow, magenta and cyan, showing the ever-changing colors in the picture. Preventive Measures For Color Deviation Of Printed Matter

     The black plate only aggravates the dark tone and acts as a skeleton. From the color rendering performance, among the four colors of yellow, magenta, cyan and black, the visual perception of yellow is the weakest, Preventive Measures For Color Deviation Of Printed Matter

     magenta and cyan are the second, and the perception of black is the strongest. Because people’s line of sight is particularly sensitive to dots with an angle of 45 °, they feel bad about dots with an angle of 0 degrees or 90 degrees, and generally feel about dots with an angle of 15 degrees or 75 degrees.Preventive Measures For Color Deviation Of Printed Matter

     In view of the above factors, the screen angle of each color plate should be determined according to the main tone of the original during plate making. Therefore, the main color printing plate of the original should be made 45 °, and other colors should be made 15 °, 75 ° and 90 °.Preventive Measures For Color Deviation Of Printed Matter

For monochrome halftone prints, we should choose a 45 degree dot. However, for multi-color halftone prints, the dot angles of various color plates must be staggered. The commonly used color screen wire angles are as follows:Preventive Measures For Color Deviation Of Printed Matter

1. For two-color printing, 45 ° screen angle is used for main color plate or dark color plate, and 15 ° screen angle is used for secondary color plate or light color plate.Preventive Measures For Color Deviation Of Printed Matter

2. For three-color printing, 45 ° screen angles are used for the main color plate or dark plate, and 15 ° and 75 ° screen angles are used for the other two-color plate.Preventive Measures For Color Deviation Of Printed Matter

3. In four-color printing, 45 ° screen angle is used for the main color plate, 90 ° screen angle is used for the yellow plate, and 15 ° and 75 ° screen angles are used for the other two colors respectively.Preventive Measures For Color Deviation Of Printed Matter

The screen cable angle is arranged according to the main color of the picture as follows:Preventive Measures For Color Deviation Of Printed Matter

(1) if the main color of the picture is the warm color of red, it can be set as: magenta 45 °, black 15 °, green 75 °, yellow 90 °.

(2) if the main color of the picture is the cool color of cyan, then: 45 ° for green version, 75 ° for black version, 15 ° for magenta version and 90 ° for yellow version.Preventive Measures For Color Deviation Of Printed Matter

(3) if the main color of the picture is black, the black version is 45 °, the green version is 75 °, the magenta version is 15 °, and the yellow version is 90 °.Preventive Measures For Color Deviation Of Printed Matter

Under normal printing conditions, arranging the screen wire angle according to the above method and correctly arranging the color sequence can effectively prevent the color deviation of the printed matter. Make the printed matter colorful and clear.Preventive Measures For Color Deviation Of Printed Matter

2： Arrangement of printing color sequence.

Color printing, whether monochrome or multi-color printing, no matter what type of ink is used, will face a problem of color sequence. Only by arranging the printing color sequence reasonably can we realize the gray balance, fully reproduce the color and level of the original, and achieve the ideal printing effect.Preventive Measures For Color Deviation Of Printed Matter

In multicolor printing, the color sequence in which the color separation plate is successively overprinted on the substrate according to a certain color sequence is called printing color sequence.Preventive Measures For Color Deviation Of Printed Matter

The arrangement of printing color sequence is very important. Its main functions include three aspects:Preventive Measures For Color Deviation Of Printed Matter

(1) correct color deviation

Yellow, magenta and cyan printing inks, no matter what brand, have a certain gray component and more or less have some color bias. There will also be some deficiencies in the whiteness of the paper we use, the accuracy of the printing press and the process operation. Preventive Measures For Color Deviation Of Printed Matter

     This will cause color deviation. Choosing a reasonable printing color sequence can make up for these deficiencies to a certain extent and correct the color deviation.Preventive Measures For Color Deviation Of Printed Matter

(2) correctly display color

The combination of three primary color inks in different proportions will show thousands of new colors. Different printing color sequences will show different color effects. If the same printing plate and the same operation process are used to overprint magenta on yellow, Preventive Measures For Color Deviation Of Printed Matter

     or overprint yellow on magenta, their color effects are different. In four-color screen printing, the dot of the dark tone part is overprinted on the dot, and the dot of the high tone part is printed on the blank part of the paper. Due to the different coverage of ink and the thickness of ink layer, the function of displayed color is also different.Preventive Measures For Color Deviation Of Printed Matter

In four-color printing, yellow, magenta, cyan and black can have 24 different printing color sequences according to the arrangement and combination. Which kind of printing has a good color sequence and has no specific provisions. Appropriate arrangements must be made according to the specific circumstances.Preventive Measures For Color Deviation Of Printed Matter

(3) reflect the overprint status

If the selected printing color sequence does not match the ink performance, there will be color mixing, ghosting, printing failure and other faults.Preventive Measures For Color Deviation Of Printed Matter

Therefore, choosing the correct printing color sequence is one of the important measures to ensure normal printing and obtain the best printing effect.Preventive Measures For Color Deviation Of Printed Matter

The selection of printing color sequence generally follows the following principles:Preventive Measures For Color Deviation Of Printed Matter

1. Arrange the color sequence according to the lightness of the three primary colors: the lightness of the three primary colors is reflected in the spectrophotometry curve of the three primary colors. The higher the reflectivity, the higher the brightness of the ink. Therefore, the brightness of the three primary color ink is yellow > Green > magenta > black. Those with low lightness shall be printed first, and those with high lightness shall be printed later.Preventive Measures For Color Deviation Of Printed Matter

2. Arrange the color sequence according to the transparency and hiding power of the three primary color ink: the transparency and hiding power of the ink depend on the difference between the refractive index of the pigment and the binder. The ink with strong covering has a great impact on the color after color stacking. Preventive Measures For Color Deviation Of Printed Matter

     As a post printing color, overprint is not easy to show the correct color and can not achieve a good color mixing effect. Therefore, the ink with poor transparency is printed first, and the ink with strong transparency is printed later.

3. Arrange the color sequence according to the size of dot area: generally, those with small dot area shall be printed first, and those with large dot area shall be printed later.Preventive Measures For Color Deviation Of Printed Matter

4. Arrange the color sequence according to the characteristics of the original: each original has different characteristics, some are warm colors and some are cold colors. In the arrangement of color sequence, the color sequence dominated by warm tone is black, blue, magenta and yellow; The color sequence dominated by cold colors is black, magenta, cyan and yellow$ Page break$.Preventive Measures For Color Deviation Of Printed Matter

5. Arrange the color sequence according to different printing equipment.Preventive Measures For Color Deviation Of Printed Matter

(1) monochrome machine color sequence: when monochrome machine prints multi-color products, the ink transfer belongs to wet stacking and drying. When considering the color sequence, the ink viscosity can be put in a secondary position.Preventive Measures For Color Deviation Of Printed Matter