1. Setting of black and white field when scanning
Newspaper printing mostly uses newsprint and rotary printing, and the smallest dots that can be reproduced are 6% -8%. Therefore, when scanning, the dot percentage of each color version of the highlight part cannot be less than 6%. If the dots are too small, it will cause the highlight part Small outlets are lost and there is a dead network. Due to the particularity of newspaper printing, it is necessary to pay attention to the total amount of ink when making a plate. The total amount of four-color ink should be between 270% and 300%, and the maximum amount of black ink can be set between 90% and 95% , And can appropriately increase the amount of background color removal to reduce the thickness of the ink layer.
2. Control when outputting film
The output accuracy of general newspapers is 85LPI-120LPI, and the dot angle is not much different from that of ordinary offset printing. Generally, the green version: 15 ° (or 75 °), the magenta version: 75 ° (or 15 °), the yellow version: 0 °, Black version: 45 ° is sufficient, and the dot angle can be adjusted according to the main color version. Regarding the requirements for the on-site density of the flexible film, generally 3.5 or more is required, and some newspapers only require 3.2 or more. The haze of the film base should be controlled below 0.08.
3. Imposition
With the development of electronic technology, imposition work can now be completed by computer software, and then output using imagesetter or CTP. The layout of the newspaper is basically fixed. Therefore, you only need to create a template in the computer to determine the size of the page, the center of the page, the sky, the foot, the fold line, the cut, etc., and the content of each page is fixed. You can add all the information required for printing (such as crosshairs, corner lines, color marks, etc.), and this template can be applied to each layout in the future, which is very convenient. The work of manual imposition is now very few. However, it should be noted that the originals provided by some advertisers are four-color films that have already been output. At this time, there are two ways to solve them: one is to use a dot copy scanner, scan the film into an electronic file, and then copy it in the computer It is combined with other content in the layout. This method has high registration accuracy and can be directly published by CTP. There is no intermediate or indirect seam during printing, and no revision is needed; another method is to manually put together two sets of film. This method has low registration accuracy, and the film that is not firmly pasted is easy to be lost. It needs to be revised after printing. If possible, the first method is recommended.
4. Exposure
When printing the newspaper, pay attention to the Brunel printing control strip to control the printing, and use 0.5% -5% of the fine dot area and micron-level line to control. It is required to reproduce 3% -5% of the dots, 97% --98% 0 outlets are not dead. In this way, the tone of the image is restored. When using the film provided by the customer to manually imposition, and then printing, it should be noted that some advertising companies produce laser printing film, the density of the laser printing film is lower than the density of the film, one is not overlapped during imposition, otherwise it is easy to cause Insufficient suction results in a false picture; the second is that the density of the printed film is different from the density of the film, the exposure time during printing is also different, the film density is larger, the printing time is longer, and the density of the printed film is small, The printing time should be shortened accordingly. In principle, after printing, the text should be clear, and there should be no shortage of strokes and full strokes.
5. Roast version
The baking version is to improve the printing plate durability. The printing volume of newspapers is relatively large. If the printing plate has a high printing durability, it can reduce the number of assembly and disassembly of the plate, save time, reduce the amount of scrap, save production costs, and also control the ink color. The baking temperature is generally around 200-220 ℃, and the baking time is 10-15 minutes.
6. Development
The daily prints of the newspaper are different, so the consumption of the developer is very large, so it is necessary to pay attention to the change in the concentration of the developer, and adjust the state of the punching machine in time according to the situation of the developed film or plate, or replace it Liquid medicine to ensure the quality of the newspaper.
7.CTP
Now CTP technology is becoming more and more mature. It simplifies some of the process of plate making, shortens the time of plate making, and also improves the accuracy. It reduces the loss of dots caused by the many processes, makes the dots restore better, and the printing plate is cleaner. CTP technology is used by many newspapers in newspaper printing. Among the various types of CTP equipment, the violet laser CTP equipment has a stable light source, long laser life and low price, and the dot reproduction range can reach 1% -99%, and the price of the plate material is low; now the thermal type promoted by major CTP manufacturers CTP equipment can be operated in the bright room. The exposure latitude is large and the resolution is very high, but the speed is slower. The newspaper can choose according to its own needs. When the newspaper chooses CTP equipment, it also needs to carefully choose a good digital process, and pay attention to the connection of various links, so that CTP can play its strengths.
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