Five printing color sequence
In multi-color overprinting, the process of overlapping and overprinting in a certain order with a single color as a unit, and finally restoring the original, is called an ink overprinting sequence, or simply a color sequence.
In traditional offset printing, the same printing plate, the same type of paper, the same series of inks, the same type of offset printing press, the same temperature and humidity, the same operator, due to the different printing sequence, the printed color effect is Not the same.
There are 24 types of overprinting sequence for combining four-color printing.
If you add light or spot colors, the combination of overprinting color sequences is even more. The most commonly-used models in actual production are the following:
Table 5-1 Color ordering of common models Color sorting machine First color Second color Third color Fourth color Four color machine Black and green goods Red and yellow color machine Black and yellow green Magenta monochrome machine Green and yellow red
Note; for reference only
The arrangement of printing color sequence is governed by various conditions. In order to obtain a good copying effect, the following basic principles should generally be followed:
(1) Arrange the color sequences according to the brightness of the three primary colors: dark color first, bright color, and then printed.
(2) According to the transparency and hiding power of the three primary colors, the color sequence is arranged: the ink with poor transparency is printed first, and the ink with strong transparency is printed after printing.
(3) According to the area occupied by the dot area, the color sequence is arranged: generally, the area of ​​the network area is small, and the area of ​​the network area is large.
(4) According to the characteristics of the original arrangement of color sequence: the warm tone of the first printing of black, blue, after printing magenta, yellow; to cool the main picture of the first printed black, yellow, after magenta, green.
(5) According to the model arrangement color sequence: monochrome or two-color offset printing press color sequence is generally yellow, magenta, cyan, black or black, cyan, magenta, yellow.
(6) Sort the color sequence according to the nature of the paper: Smooth, tight paper first prints dark colors, and later prints bright colors; thick, loose paper first prints bright colors, and later prints dark colors.
(7) According to the dryness of the ink, the color sequence is arranged: the slow drying ink is printed first, and the fast drying ink is printed.
(8) According to the flat network and the field arrangement of color order: flat-screen graphic first printed, the real structure of the post-print.
(9) According to light and dark ink arrangement color sequence: dark ink first printing, light or spot color ink after printing.
(10) According to the rules of fitting, color change is easy to arrange the color sequence: the main color or strong color combination as close as possible in a piece of printing, can not be separated. In addition, the color sequence must take into account the convenience of color change, otherwise it will increase the auxiliary time.
For a multicolor offset printing press, in the wet and wet printing state, whenever the first color ink film printed on the paper is overprinted with the second color, the third color, and the fourth color, they are sequentially erased by the eraser. The cloth roller sticks away some of the ink. Among them, only the third color ink is the least sticky, except that the fourth color ink is 100% retained on the paper. Therefore, the third color sequence and the fourth color sequence constitute the most critical two of the printing color sequence. Color sequence. Therefore, the decisive color must be arranged in the third and fourth color sequences so that it can meet the requirements of any hue manuscript and is easy to restore the hue. At the same time, the effect of ink hiding is avoided. Therefore, it is better to highlight the main color of the picture. In short, the color-sequencing arrangement is a very important and complicated issue. It must be analyzed specifically on specific issues and must not be conducted blindly.
For a monochrome offset press, it is printed in a wet, dry state so that the arrangement of the color sequence cannot follow the color sequence of a multicolor offset press.
[Case: 5-4]
A unit printed a cigarette pack with a J2205 machine. The pattern is a big butterfly. The single-sided coated paper of 80g/m2 was used. Its color sequence was black, blue, red and yellow. As a result, it was found out that printing was inaccurate and the printed products were almost completely scrapped.
[Case Analysis]: The paper used in this product is the most easily retractable paper. Therefore, special attention should be paid to the arrangement of the color sequence and the control of the wetting fluid when printing. Obviously, black, blue, red and yellow are the first two colors. After printing in the group of two colors, printing blue and red in the two-color group will inevitably result in overprinting. It appears that this type of paper is printed by the J2205 machine. The color sequence should be yellow, black, red and blue. better.
[Case 5-5]
A factory used a four-color monochrome offset press to print a poster featuring 128g/m2 double copper and 1,000 copies. The color sequence used by the operator is black, sky blue, magenta, and yellow, and the screen presented by the printed product is boring and dark as a whole.
[case analysis]:
For monochrome machines, this arrangement is unreasonable. One is not conducive to color-changing cleaning, and the other is that black and blue are both too large and too small to be remedied. If the prints appear to be dark and dark, it means that black, sky blue and black may be too large. Therefore, this color arrangement is not reasonable. It is reasonable to print in the order of sky blue, yellow, red, and black.
[Case 5-6]
A factory used a white embossed paper to print the color insert of a magazine. The model used was the J2108 type machine. The color sequence was sky blue, yellow, magenta, and black. The result was a poor print. Mainly color image stereo feeling is not strong.
[case analysis]:
The above phenomenon often occurs. The surface of a substrate such as embossed paper is not smooth and the blackness is poor. Therefore, the color sequence should be corrected as follows: yellow, magenta, cyan, and black. The reason is that the yellow version has a long tone and a large area. Printing on embossed paper can play a good role in the background color, and then magenta, cyan and black inks are printed in sequence. The effect of this is just fine.
[Case 5-7]
A certain customer wants to print a batch of magazine covers. Most of the background of the cover uses "technical blue", that is, the magenta is 25% of the cable, and the green is 100% in the field. In the four-color offset printing, the conventional color sequence is black, cyan, magenta, and yellow. The phenomenon of dark blue soiling often occurs during printing. Later, the viscosity of the magenta ink is reduced, and the viscosity of the blue ink is increased. The problem is not solved.
[case analysis]:
Since the four-color offset printing press is wet-on-wet printing, when the other color ink is superimposed on the wet solid, the transfer effect is poor and the ink transfer rate is low. In this example, if magenta is placed in front of cyan, that is, the color sequence is black, magenta, cyan, and yellow, this sample red will be transferred to the paper by 100%, the transfer rate will be the highest, and the cyan field will also have Three-quarters of the area is directly transferred to the paper, and printed prints are relatively flat.
Treatment methods: First, use coated paper and advanced ink printing. The second is to change the printing sequence.
Source: Ke Yin Network