What is the stress on lithographic paper?

Lithography course: /jpkc/002/jiaocai/shiban.doc plate refers to the material of printing media, and its material attributes and characteristics are related to specific printing methods. As mentioned in the first part of this course, lithographic printing plates take lithograph as the original, and also include metal plates and other plates with basically the same use method and printing effect as lithograph. 1. Lithography Lithography Lithography is a limestone slab with uniform texture, which is called micrite limestone in geology. This kind of rock is formed in a low-energy sedimentary environment without waves, currents and ocean currents, so it has the characteristics of pure quality, light color, fine and porous structure, strong water absorption, hard texture and pressure resistance. The inventor of lithograph did not choose this stone for printing research at that time, but all the techniques of lithograph were tested and finally determined around this stone, and the characteristics of stone became one of the necessary factors of lithograph. When lithographing became popular in the world, this widely used micrite limestone was called lithographed limestone, and the mined slate was called lithographed limestone. (Figure 1) Lithography stone used by the inventor of lithography is produced in Franknia, Germany, and the deposit is near Solhoven. When this kind of stone was widely developed and used with the spread of lithography, it was called Yin Shi of Sonerhofen. Generally, the mining specification of rock ink is 8 to 12㎝ thick. There are 80㎝×60㎝, 60㎝×48㎝, 54㎝×38㎝, 40㎝×28㎝ and other different sizes. Larger and thicker ones are rare. There are several kinds of lithographs, such as dark gray, light gray and yellow, and the texture and lithograph characteristics are different. Dark gray lithograph is fine and hard, suitable for large-scale printing. However, the dark color leads to poor image resolution when drawing the board, which is not suitable for lithography. Light gray and yellow lithographs are better than dark gray lithographs in fineness, hardness and corrosion resistance, but they are lighter in color and can distinguish subtle tones when drawing, which is more suitable for non-large-scale lithographs. Due to the small number of prints, there is basically no difference in texture and printing effect. (Figure 2) At the beginning of the 20th century, when lithographs were introduced to China, a considerable number of German lithographs were imported and used for lithograph printing in various places. When more advanced printing technology is adopted one after another, lithography gradually fades out of the industrial printing field, and lithography is idle or used for other non-printing purposes; The use of lithographs in China's artistic creation is relatively backward. The popularity of lithographs was after the 1980s, when a large number of lithographs were destroyed and lost. There is a big time lag between the elimination of lithography and the acceptance of artistic creation, which is very different from the natural alternation of lithography in Europe and America. Therefore, although there is still room for searching and collecting lithographs in China, it is few after all, and most of them are concentrated in major art colleges with lithograph studios. China has a vast territory and abundant resources, and is rich in stone minerals. As early as when Lithography was introduced to China, people were looking for stones that could replace German Lithography in China. Similar stones have been mined in Liaoning, Sichuan and Hunan. The domestic lithographs that can be seen now are grayish red, and the plate-making performance is similar to that of German lithographs. 1994 Professor Guo Zhaoming of Hubei Academy of Fine Arts found a kind of stone bed which can be used for lithographing in southwest Hubei, and it was dark gray. Tested by relevant departments, its main composition and structure are similar to those of German lithographs, which are proved to be available by experiments, but the texture is hard, so it should be treated with concentrated nitric acid when making plates. At present, all kinds of lithographs have been used in various art colleges in China. 2. As early as 180 1 year, the lithograph industry has completely replaced slate with zinc plate. By 1870, the use of metal plates kept pace with the use of lithographs. Slate is heavy, which is not convenient for work and use, while metal plate is light and easy to carry, and the use method and printing effect are not much different from slate, which is the main reason why metal plate joins the lithographic ranks; In addition, the metal plate can be curled, that is, it can be printed in a flat way like lithography, and more printing methods can be used, which provides the possibility for the development of modern offset printing. All kinds of metal materials can be used to make lithography, among which zinc and aluminum are moderately lipophilic, so they are widely used in lithography industry. Zinc plate for printing is a thin metal sheet made by adding trace metal elements needed for printing plate to industrial pure zinc, and can also be used as copper plate printing material; Some zinc plates have high lead content and are thinner than zinc plates. They are usually called "lead skins" and are special metal plates for lithography, which are rare now. Aluminum plate for lithography is a thin sheet made by adding trace metal elements such as iron and manganese into industrial pure aluminum, and its acid resistance is better than that of zinc plate. Zinc plate and aluminum plate have different uses. One is that the color depth is different. Aluminum plate is light in color, and its color resolution is higher than that of zinc plate when drawing. Second, the hardness of zinc plate and aluminum plate is different. Zinc plate is harder than aluminum plate, has strong compression resistance and is suitable for multiple printing. (Figure 3) 3. In the early 1950s, PS plate, which was pre-coated with photosensitive layer on the plate base, was called pre-coated photosensitive plate internationally, and PS plate (abbreviation of presensitized platede) was the most widely used plate in China's printing industry. Its plate base is aluminum plate, which consists of plate base, oxide layer, lipophilic layer and photosensitive film layer. PS version is light in weight, fine and uniform in layout, good in moisture retention, high in photosensitive resolution, excellent in printing performance, convenient and fast. The image on PS plate needs to be formed by photosensitive method and can be formed in transparent sand.