Newspapers are generally printed using high-speed web-fed printing machines. The surface of the paper is rough, the paper path is long, the width is wide, the printing speed is fast, and the ink is dried by permeation drying. There are many different requirements for pre-press production from printing other fine products. Those who have long been engaged in color newspaper printing will have such experience: Some color newspapers are very good, even if the equipment, paper and other conditions are worse, the printed products are also very beautiful. Some color newspapers are difficult to adjust the color of ink, the field is difficult to print uniform, slightly worse, obviously overprinting is not allowed, the amount of ink is small - some color gray, large amount of ink and easy to dirty. When these conditions arise, people are more often blamed for poor print quality. In fact, in many cases, it is the cause of prepress production, or it can be significantly eased by improving prepress production. So, what quality problems arise in printing and prepress production?
1. Tonality is difficult to adjust, easy to change, not easy to print uniform color palette is very difficult, especially in large-scale deep-tuning part or title, network, it is not easy to put ink, but also easy to change, not easy to print uniform. The reason is that producers do not understand the special printing of newsprint, yellow, magenta, and cyan are too dark, and the balance of gray is difficult to control.
The solution is to increase the black version, replace the grey component with a black version, and reduce other color versions. In this way, it is better to grasp the black version of the text when printing, as long as the black version is normal, even if the other color version is worse or has slight changes are not obvious, and the color is relatively easy to stabilize in the printing. This is why the same color newspaper, some normal pre-inking, a boot color is basically the same. However, some colors are not easy to adjust, and they are easy to change and are not easily uniform.
2. There are many reasons for the unclear level of the picture and the leveling of the picture caused by the stencil, and there are many reasons for stencil printing. However, when the same machine prints other products, it is very good. For another product, the picture level is unclear, and the proof is far from the proof. The question now is whether or not there should be a problem with prepress production. For example, if the image is too dark, the area is too large, the tone value is set too high, the picture contrast is not enough, and the number of network lines is too high. In particular, the film produced or provided by the customer itself often only pays attention to the effect of the display or the effect of the copper plate pattern. It does not take into account the print characteristics of newsprint itself.
Newsprint surface is rough. Surface roughness and brightness are low. Dot reduction is much worse than coated paper. Therefore, the newly promulgated national standard GB/T17934.3-2003 "Cold-printing press offset printing for newsprint" states: For monochromatic and color printing, the number of mesh lines should be 85-120lpi; the tone reproduction range is 5%-85. %; The sum of tone values ​​must not exceed 260%.
Some customers think that the higher the number of film screens, the better the number of screen lines used; some advertisers use printed film paper to print newsprint; some customers set the total tonal value is too high. The tone is too dark; there may be poor quality of the original of the picture or the operator's inexperience in producing the newspaper, etc. These will cause the reproduction of the picture to be difficult and even make a copy.
The solution is: select the manuscript suitable for newsprint printing as much as possible; the number of screen lines output by the film is black and white 85~100lpi, color 100~120lpi; the sum of the order of decay values ​​is less than 260%; Should exceed 85%; and increase the contrast moderately.
3. Dirty, dirty, dirty, dirty - straightforward newspaper printing is difficult to solve the problem. In addition to the paper, ink properties and equipment, the main reason is the unreasonable prepress production. The main reason why pre-press production has become dirty is that the sum of picture tonal values ​​(also called the total amount of ink) is set too high. The “total sum of tone values ​​must not exceed 260%†as stipulated in GB/T 17934.3-2003 is based on the insufficient color saturation of domestic inks. In fact, the sum of tone values ​​should be lower (not more than 240%) to be more conducive to ink drying and not easy to pick up. Many customers do not understand this, and they always require full color, and the sum of tone values ​​is not set at more than 280%. This is undoubtedly the most important cause of dirtying and stenciling.
The solution is: set the sum of tone values ​​in strict accordance with national standards, and as low as possible to 260%; at the same time increase the color purity, depress the opposite color, reasonably use the background color removal function, and moderately increase the contrast. Only in this way can we ensure that the pictures are of a vivid color, meaning that it is not easy to cause piles of ink, dirt, and dirt.
4. Why is overprint not allowed to register? Why is it related to prepress production? Actually, the personnel engaged in printing have such a personal experience. Some newspapers even if overprinting are worse, they do not affect the overall effect; while some newspapers are overprinted. If you are not allowed, it is very obvious.
Registering is an important index for measuring the quality of color newspapers, and the registration of color newspapers is constrained by various factors, including: the level of craftsmanship, whether it is direct plate making or traditional plate making; it is full page output or manual single spelling; The print version is still small; it is a big roll printing or a small roll printing; and paper, equipment status and timeliness, and so on. Therefore, inaccurate overprinting is not only the most important index reflecting the quality of printing, but also the problem that cannot be avoided or fundamentally solved by various conditions. The "national standard" stipulates that the overprint error is less than 0.3mm. It is formulated in consideration of the above factors. Since it is difficult to overcome, it is necessary to consider how to avoid the problem of poor pictures caused by overprinting when it is printed.
Through actual printing, it is found that yellow, magenta, cyan, and black versions are all heavy, not only difficult to print, easy to paste version, but also a little inaccurate. However, when the black version is heavy and the other color versions are light, even when the errors of other color version overprints are large, it is not obvious. This is a problem that should be considered in prepress production in order to solve the printing deviations that are inevitable in printing.
5. Against the background Pressing the inscription or directly pressing the inscription on a deep background or background will reverse the background. Some customers comment on this. They think this is because the inscription is so small that it cannot be suppressed and requires more ink. This will not only affect the level of the picture, but also cause the ink layer to be too thick, dirty, dirty.
The solution is: hollowing out or increasing the cyan version of the black heading.
6. Paste words Multi-color printing and deep-web (ground) anti-white ink, unrecognizable newspaper printing is another big problem. In particular, advertisements are often seen as cases where printing companies are unreasonably demanding payment or refusing to pay printing fees. In fact, under the high-speed printing of more than 2000 pairs (or copies) per minute, any jitter of the paper will instantly result in overprinting. This is what no one can do and what is inevitable. Therefore, in order to solve the above problems of multi-color embossing and deep-web (ground) anti-whitening, it is necessary to design and produce manpower from the early stage. According to actual measurement, even if the word of the Song type is 3 large, it is printed on paper, but the crossbar is only 0.10mm. This means that even if the printed newspapers are all high-quality newspapers, the registration error is less than 0.15mm, and No. 3 Song type multi-colored laminated or anti-white characters cannot be identified. Therefore, a clear specification must be made for the font and font size of multi-colored overlays or inverted texts. Take Renmin Ribao Printing Factory as an example, the number 5 bold type (crossbar width of about 0.25mm) is used as a reference, in accordance with the overprint error requirement of the “national standard†regulation is less than or equal to 0.30mm, and the number of multicolor overlay or inverted text, The following rules are specified in the font: (1) Multicolored words cannot be multicolored, regardless of the font size. (2) Text below No. 5 cannot be multicolored or reversed white; (3) When multi-color overlaying or reverse whitening is required, only No. 5 or higher boldface can be used (No. 4 blackbody crossbar width is about 0.30mm ); (4) For products with many manual collages, poor paper conditions or high quality requirements, the restrictions should be raised. These are best based on the actual situation, in the signing of the contract with the customer, clearly written into the contract.
In addition, pre-production in the handling of multi-color printing should also comply with: can use monochrome without two-color; can use two-color instead of three-color; more than three colors to increase the proportion of the black version, reduce the principle of other color version, try to meet While designing requirements, creating conditions for printing.
7. The title and field are not true. It is generally believed that the headlines pressed by the field or the larger color bars and color blocks are more saturated in color, but in the actual printing, the large headings or areas with larger colors are found in the actual printing. Bars and color blocks are easy to make and print, and they are not easy to print, and they can easily cause squaring. The larger the title and color area, the more obvious this phenomenon is. The use of 85% ~ 95% of deep nets instead of the field will receive unexpected results. For newspapers with high timeliness and high volume, this approach is even more effective. Because the plate will seriously affect the quality, sometimes even if you can change the version, because time does not allow, but also can not do anything. This is also one of the reasons why the title and the field are unrealistic, flowery, and color cast. In addition, this approach can also make up for equipment and other deficiencies, which is also an example of how prepress production should create conditions for printing as much as possible.
In short, there are a lot of quality problems in the printing that are caused by the innate shortcomings of prepress production. Through the production, the quality of printing can be solved or mitigated to some extent. In particular, printing in color newspapers, pre-production is particularly important.
1. Tonality is difficult to adjust, easy to change, not easy to print uniform color palette is very difficult, especially in large-scale deep-tuning part or title, network, it is not easy to put ink, but also easy to change, not easy to print uniform. The reason is that producers do not understand the special printing of newsprint, yellow, magenta, and cyan are too dark, and the balance of gray is difficult to control.
The solution is to increase the black version, replace the grey component with a black version, and reduce other color versions. In this way, it is better to grasp the black version of the text when printing, as long as the black version is normal, even if the other color version is worse or has slight changes are not obvious, and the color is relatively easy to stabilize in the printing. This is why the same color newspaper, some normal pre-inking, a boot color is basically the same. However, some colors are not easy to adjust, and they are easy to change and are not easily uniform.
2. There are many reasons for the unclear level of the picture and the leveling of the picture caused by the stencil, and there are many reasons for stencil printing. However, when the same machine prints other products, it is very good. For another product, the picture level is unclear, and the proof is far from the proof. The question now is whether or not there should be a problem with prepress production. For example, if the image is too dark, the area is too large, the tone value is set too high, the picture contrast is not enough, and the number of network lines is too high. In particular, the film produced or provided by the customer itself often only pays attention to the effect of the display or the effect of the copper plate pattern. It does not take into account the print characteristics of newsprint itself.
Newsprint surface is rough. Surface roughness and brightness are low. Dot reduction is much worse than coated paper. Therefore, the newly promulgated national standard GB/T17934.3-2003 "Cold-printing press offset printing for newsprint" states: For monochromatic and color printing, the number of mesh lines should be 85-120lpi; the tone reproduction range is 5%-85. %; The sum of tone values ​​must not exceed 260%.
Some customers think that the higher the number of film screens, the better the number of screen lines used; some advertisers use printed film paper to print newsprint; some customers set the total tonal value is too high. The tone is too dark; there may be poor quality of the original of the picture or the operator's inexperience in producing the newspaper, etc. These will cause the reproduction of the picture to be difficult and even make a copy.
The solution is: select the manuscript suitable for newsprint printing as much as possible; the number of screen lines output by the film is black and white 85~100lpi, color 100~120lpi; the sum of the order of decay values ​​is less than 260%; Should exceed 85%; and increase the contrast moderately.
3. Dirty, dirty, dirty, dirty - straightforward newspaper printing is difficult to solve the problem. In addition to the paper, ink properties and equipment, the main reason is the unreasonable prepress production. The main reason why pre-press production has become dirty is that the sum of picture tonal values ​​(also called the total amount of ink) is set too high. The “total sum of tone values ​​must not exceed 260%†as stipulated in GB/T 17934.3-2003 is based on the insufficient color saturation of domestic inks. In fact, the sum of tone values ​​should be lower (not more than 240%) to be more conducive to ink drying and not easy to pick up. Many customers do not understand this, and they always require full color, and the sum of tone values ​​is not set at more than 280%. This is undoubtedly the most important cause of dirtying and stenciling.
The solution is: set the sum of tone values ​​in strict accordance with national standards, and as low as possible to 260%; at the same time increase the color purity, depress the opposite color, reasonably use the background color removal function, and moderately increase the contrast. Only in this way can we ensure that the pictures are of a vivid color, meaning that it is not easy to cause piles of ink, dirt, and dirt.
4. Why is overprint not allowed to register? Why is it related to prepress production? Actually, the personnel engaged in printing have such a personal experience. Some newspapers even if overprinting are worse, they do not affect the overall effect; while some newspapers are overprinted. If you are not allowed, it is very obvious.
Registering is an important index for measuring the quality of color newspapers, and the registration of color newspapers is constrained by various factors, including: the level of craftsmanship, whether it is direct plate making or traditional plate making; it is full page output or manual single spelling; The print version is still small; it is a big roll printing or a small roll printing; and paper, equipment status and timeliness, and so on. Therefore, inaccurate overprinting is not only the most important index reflecting the quality of printing, but also the problem that cannot be avoided or fundamentally solved by various conditions. The "national standard" stipulates that the overprint error is less than 0.3mm. It is formulated in consideration of the above factors. Since it is difficult to overcome, it is necessary to consider how to avoid the problem of poor pictures caused by overprinting when it is printed.
Through actual printing, it is found that yellow, magenta, cyan, and black versions are all heavy, not only difficult to print, easy to paste version, but also a little inaccurate. However, when the black version is heavy and the other color versions are light, even when the errors of other color version overprints are large, it is not obvious. This is a problem that should be considered in prepress production in order to solve the printing deviations that are inevitable in printing.
5. Against the background Pressing the inscription or directly pressing the inscription on a deep background or background will reverse the background. Some customers comment on this. They think this is because the inscription is so small that it cannot be suppressed and requires more ink. This will not only affect the level of the picture, but also cause the ink layer to be too thick, dirty, dirty.
The solution is: hollowing out or increasing the cyan version of the black heading.
6. Paste words Multi-color printing and deep-web (ground) anti-white ink, unrecognizable newspaper printing is another big problem. In particular, advertisements are often seen as cases where printing companies are unreasonably demanding payment or refusing to pay printing fees. In fact, under the high-speed printing of more than 2000 pairs (or copies) per minute, any jitter of the paper will instantly result in overprinting. This is what no one can do and what is inevitable. Therefore, in order to solve the above problems of multi-color embossing and deep-web (ground) anti-whitening, it is necessary to design and produce manpower from the early stage. According to actual measurement, even if the word of the Song type is 3 large, it is printed on paper, but the crossbar is only 0.10mm. This means that even if the printed newspapers are all high-quality newspapers, the registration error is less than 0.15mm, and No. 3 Song type multi-colored laminated or anti-white characters cannot be identified. Therefore, a clear specification must be made for the font and font size of multi-colored overlays or inverted texts. Take Renmin Ribao Printing Factory as an example, the number 5 bold type (crossbar width of about 0.25mm) is used as a reference, in accordance with the overprint error requirement of the “national standard†regulation is less than or equal to 0.30mm, and the number of multicolor overlay or inverted text, The following rules are specified in the font: (1) Multicolored words cannot be multicolored, regardless of the font size. (2) Text below No. 5 cannot be multicolored or reversed white; (3) When multi-color overlaying or reverse whitening is required, only No. 5 or higher boldface can be used (No. 4 blackbody crossbar width is about 0.30mm ); (4) For products with many manual collages, poor paper conditions or high quality requirements, the restrictions should be raised. These are best based on the actual situation, in the signing of the contract with the customer, clearly written into the contract.
In addition, pre-production in the handling of multi-color printing should also comply with: can use monochrome without two-color; can use two-color instead of three-color; more than three colors to increase the proportion of the black version, reduce the principle of other color version, try to meet While designing requirements, creating conditions for printing.
7. The title and field are not true. It is generally believed that the headlines pressed by the field or the larger color bars and color blocks are more saturated in color, but in the actual printing, the large headings or areas with larger colors are found in the actual printing. Bars and color blocks are easy to make and print, and they are not easy to print, and they can easily cause squaring. The larger the title and color area, the more obvious this phenomenon is. The use of 85% ~ 95% of deep nets instead of the field will receive unexpected results. For newspapers with high timeliness and high volume, this approach is even more effective. Because the plate will seriously affect the quality, sometimes even if you can change the version, because time does not allow, but also can not do anything. This is also one of the reasons why the title and the field are unrealistic, flowery, and color cast. In addition, this approach can also make up for equipment and other deficiencies, which is also an example of how prepress production should create conditions for printing as much as possible.
In short, there are a lot of quality problems in the printing that are caused by the innate shortcomings of prepress production. Through the production, the quality of printing can be solved or mitigated to some extent. In particular, printing in color newspapers, pre-production is particularly important.
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