Improve the printing quality of color newspapers through process standardization

In the age of the knowledge economy, the coverage of information is more extensive, information is disseminated more quickly, and the channels for transmission are increasingly diversified. The market share of traditional information media, newspapers, is being eroded by online media, electronic media, and broadcast television media. Many newspapers print In order to maintain their original market share, companies have increased their input, introduced new technologies, new equipment, or made technological changes to print more competitive color prints in order to meet the needs of consumers and advertisers.

Color newspaper is more attractive

With the improvement of material living standards, people's demand for culture has also changed. The past “black and white world” has been unable to meet people's needs. At present, the print volume of color newspapers in China accounts for 1/3 of the total print volume of newspapers, and this proportion is still increasing. According to a survey conducted by ZMG in Germany, colored newspapers are more attractive than monochromatic newspapers. Color newspapers with the same information receive 25% more attention than monochromatic newspapers. Color newspapers with the same information are better than color newspapers. The degree of concern is 15% higher. The survey also shows that although color newspapers have attracted more attention, many advertisers have reservations about printing color advertisements in newspapers. Because they believe that there are many deficiencies in publishing color advertisements in newspapers as opposed to advertising in other media, such as cumbersome processes and complicated operations. What is more important is that there is still no unified uniform printing quality standard in the field of newspaper printing. It is difficult for a printing company to ensure that the same printed matter printed in different places or the same printed matter printed at the same place at different times remains approximately the same in color and tone. For this reason, advertisers spend a lot of time and money each year to explain and deal with their customers.

As a printing company, how can advertisers' complaints and complaints be reduced? Only the introduction of the concept of standardization in the field of color newspaper printing can effectively reduce print quality problems, reduce customer accusations of quality issues, re-inspire traditional customers, and create higher levels. Economic benefits.

Standardization of color newspaper printing

We know that there are many standards that require performance and indicators for common products, such as enterprise standards, industry standards, and national standards. However, these standards can not fully meet the requirements and needs of customers. Only by standardizing the process can we produce products that meet the needs of consumers.
In the implementation of standardization in the field of color newspaper printing, I think we should consider from the following aspects:

Prepress process standardization

1. The definition of the original quality. There are many types of originals used for newspaper printing, such as film, sulfuric acid paper, photo paper, negative film, reversal film, and digital documents. In order to ensure the quality of the production, the manuscript should be defined, such as: the tone level, color tone, sharpness and completeness of the specified image manuscript; the line width, character type, character size, gradient type, and shadow of the specified graphic manuscript. .
2. Unified file format for digital files for prepress processing. Advertising operators, editors, and authors are all providers of prepress digital manuscripts. The digital file formats they provide are various. However, there are still a large number of newspaper printing companies that cannot accept the PDF file format and XML language. This requires the advertising operator to convert the PDF file format or the XML language into the Postscript file format, thus causing difficulties for the prepress standardization.
3. Consolidation of parameters in digitized manuscript processing. It is difficult to ensure that the digital manuscripts provided by advertising operators, editors, and authors are completely consistent in terms of parameters such as scanning resolution, tone levels, and color space. People should specify uniform image input resolution, contrast range, UCR, GCR and so on.
4. The ICC characteristic curve is used to control the proof output, the output of the film and the direct output of the printing plate. Digital proofing technology has the advantages of fast proofing speed, no need to output complicated procedures such as film, imposition, printing, development, and traditional proofing, which can significantly reduce the influence of human factors on the quality of proofing and is increasingly valued by the newspaper printing community. In order to make better use of digital proofing technology, to achieve matching between proofing products and printed products, and to stabilize the printing quality, the output must be controlled by means of the ICC characteristic curve.
5. Uniform output parameters. The output process should fully take into account the actual situation of the printing company and people's requirements for the product, select the appropriate number of screens, screen angle, dot shape and the appropriate gray level, to avoid the appearance of rose spots and moire. However, the number of screens currently provided by customers may be 28, 30, 32, 34, 36, or 40 lpcm, and the reproduction range of reproduction may be 4% to 96% and 12% to 86, respectively. %, 0% to 85%, 20% to 100%, and 7% to 94% of the middle segment. Therefore, it is difficult for people to ensure that the appearance of multiple network lines and multiple screen angles does not occur on the same printing plate, and it is difficult to ensure the printing quality of printing plates and the stability of printed matter.
6. The black density of the output film and the output of the sulfuric acid paper and the virtual reality of the outlets are stipulated, ensuring the normal operation of the printing machine, finding the ideal exposure time and developing time of the printing plate, etc., which are all issues that should be considered in the prepress standardization. In order to better control the printing quality and printing quality, it is best to add printing and printing control strips on each printing surface of the newspaper.

Material purchase standardization

As the saying goes: It is difficult for a clever woman to be without rice, and without good printing materials as a backing, it is difficult to print an ideal print. Therefore, to do a good job in newspaper printing quality, we must first start with raw materials, strictly control the quality of raw materials when entering the factory, and resolutely put an end to unqualified printed materials from entering the factory. Only if these raw materials meet the standards set by the industry can print products that meet the standards be produced.
1. Paper purchases. The roughness, whiteness, smoothness, smoothness, tensile strength, ink absorption, degree of sizing, and moisture content of the paper surface all affect the print quality of the printed matter.
2. Printing ink procurement. Ink is a colorant that exhibits a printed pattern. The hue, color purity, transparency, viscoelasticity, color strength, fineness, rheology, and dryness of the ink also affect the print quality of the print.
3. Printing Plate Procurement. Whether it is a normal offset printing plate or a CTP printing plate, their resolution, ink absorption, hydrophilicity, and resistance to printing will affect the quality of the printing copy.
4. Fountain solution purchase. The chemical composition, pH, and conductivity of the fountain solution can affect the print quality.
5. Purchase of other accessories. For example: blankets, desiccants and so on.

Standardization of the printing process

1. Define the printing pressure. The appropriate minimum printing pressure should be found during printing. The water and ink rollers should be pressure-regulated according to data and standardization, and the drums should be cushioned by data and normalized adjustments.
2. Define the ink balance. In offset printing, water consumption is reduced as much as possible while maintaining the balance of water and ink.
3. In the specific production of offset printing, we should be diligent ink fountains, diligently look at the water, diligently look at the proofs.
4. Look at the sample platform should use standard light sources. People often use a neutral light source of 5000K. If the light source is bright, it will cause the printed product to be bluish, which will result in a reddish appearance of the printed product.
5. Control the temperature and humidity in the offset printing shop.
6. Registration error. According to GB/T 14705-93 formulated by the General Administration of Press and Publication of China, the allowable registration error of color newspaper prints is: the main part (0.05 mm), the general part (0.07 mm), and there is no color leakage at the edges of the color photos. Positive and negative register error does not exceed 2mm.
7. Ensure that the printing network is clear and strong, no deformation, no moire, no lack of color, no paste version, the image network line area and the field area does not appear white spots and pull hair phenomenon, no ink, pressure dirty.

Make full use of print quality control strips and measuring instruments

The print quality control bar can objectively reflect the change of the dot in the printing and copying process at any time, giving the printer instructions. The printer can adjust the pressure, amount of ink and water according to the relevant information, change the error in the operation process at any time, and ensure the stability of the product quality.

We must always use the reproduction of the neutral gray balance as the most important means of controlling the printing quality. Since printing surfaces are printed on each printing surface of the newspaper, we can use the density and chromaticity measuring instruments to evaluate the tone reproduction. . For example, density meters are used to measure solid density, dot density, and dot gain. Color monitors are used for color calibration and measurement of computer monitors, calibration of digital proofing equipment, evaluation of digital proofing products, and evaluation of solid color reproduction. . In the entire printing production process, only the measurement process is used to make the process smoother and the production tends to be stable. Whether in the density measurement or the colorimetric measurement, it must be noted that the measuring instrument must first be zeroed and calibrated. During the measurement, the printed matter to be tested should be laid flat to ensure that the measuring head is in close contact with the block to be measured and measurement errors are reduced. In the printing production, the internationally-recommended recommended standards are used in combination with the actual measurement results to guide the printing with numerical values, which promotes the improvement of newspaper printing quality and reproduces the desired printing effect.

1. Grey balance control. In color reproduction, gray balance reproduction is an important means of verifying that color reproduction is realistic. The color balance produced by overprinting the three primary colors of ink is a small area close to neutral gray. In most cases, the visual impression of the color balance block is close to neutral grey, and its gradation value roughly corresponds to the adjacent real gray block. It is very sensitive to changes in color and tone values ​​during the printing process. By controlling the color balance of the bars, the shift in color balance can be found.

2. Solid density. The measurement and control of on-site density is the basis for objectively evaluating print quality. Generally, the color density of solid-colored newspaper prints is controlled at: yellow (0.8), magenta (0.9), cyan (1.0 to 1.2), and black (1.0 to 1.3).

3. Network expansion. Dot enlargement is an unavoidable phenomenon in offset printing. The maximum dot gain of 401/cm prints can reach: positive-printing plates (27%) and negative-tone printing plates (33%).

Reprinted from: "Printing Magazine"