The smoothness of the paper refers to the surface roughness of the paper. Paper flatness is a very important paper performance index. There is a certain degree of difference between the smoothness of the paper and the print smoothness. As the effect on the print quality is discussed, the paper only refers to the print smoothness of the paper. The smoothness of newsprint is low in all types of printed paper. Its composition is mainly long fibers. It is filled with short fibers and properly calendered. The surface smoothness is low. At present, the offset printing process has been widely used in the production of newspapers. Offset printing is produced by the principle of immiscible oil and water. Its printing pressure is lower than that of lead printing. In order to obtain good graphic quality, we must ensure that the paper has a good surface. Smoothness. Newspapers produced on paper with a smoother surface, due to better contact during printing to transfer the ink, can obtain a higher dot quality, allowing the graphic image to be reproduced clearly and plumply on the paper. With the development of the newspaper industry in recent years and the expansion of the production of color newspapers, the requirements for the surface smoothness of paper have also been continuously improved.
Dots are the basic elements of the printing tone reproduction. The 50% dots at 100 LPI are only about 0.2 mm in diameter. If the surface smoothness of the paper is poor, the dots will easily cause the phenomenon of incomplete deformation and cause the loss of small dots, which will affect the reproduction of the picture and the quality of the picture and picture, and will particularly affect the reproduction of subtle levels. In order to coordinate the complete reproduction of the picture level, it is necessary to ensure that the dots on the paper have a clear and accurate form. We have such experience that the better the surface thirst of the paper, the higher the reproduction quality of the dot and the clear and neat ideas. From a microscopic point of view, the coarse paper surface will not fully transfer the ink of the dots here due to insufficient pressure in the recesses, resulting in a certain degree of dot distortion or even incompleteness. The quality of the newspaper will be affected obviously; the smoothness of the paper High, the small outlets in the printing process are not easily lost, which can effectively ensure that the picture text is rich in layers and the color reproduction is good.
In addition, the higher the number of lines, the richer the picture layer, and the higher the number of screen lines, the smaller the diameter of the dots at the same coordination point. This also requires that the paper with good surface smoothness is not printed, therefore, The number of meshes and print paper smoothness are also of great relevance. However, the number of complaints in the newspaper is not fixed. Newspaper printing requires that the paper have a good surface smoothness to maximize the number of hanging copies and ensure that the copy quality of the picture text is more refined. The number of newspapers printed with the same amount of money is generally around 80100 LPI. In the case of ensuring the smoothness of the surface of the paper, properly increasing the number of pictures on the screen is also one of the means to improve the printing quality of newspapers. That is to say, newspapers with good surface smoothness should be used for newspaper production as much as possible, and the number of hanging nets can be appropriately increased to improve the printing quality of newspapers.
Compared with black and white newspapers, the quality of outlets has a greater impact on print quality. The color newspaper emphasizes a "color" word. To ensure the quality of important color elements such as pictures, titles, bottom nets, and maps, it is important to improve the reproduction quality of the outlets. The black-and-white newspaper outlets are mainly used for the reproduction of pictures, and the color newspaper outlets are very important for the reproduction of color, level, and coordination. In order to ensure the quality of the reproduction of pictures, color newspapers generally have a higher number of identities than black-and-white newspapers. Therefore, the requirements for the level of clarity of papers for color newspapers are also high.