The general screen-printing process does not need to be described in detail. Here we will briefly discuss the special part of the large-scale screen-printing and advertising plate-making.
First, the manuscript
The originals of large-scale advertisements are much smaller than the finished ones, and the originals must be enlarged to be enlarged by several hundred times. Therefore, it is necessary to carefully examine the manuscript (color reversal film) with a magnifying glass of 10 times or more, and it is required that the manuscript be clear in outline, uniform in color, bright in color, and moderate in contrast. Large-scale advertising manuscripts must be carefully photographed with professional photographic equipment and professional advertising photo technicians. Printing is the copying of a manuscript, and the copy is not overwritten. We always say that China's printed matter is not as exquisite as foreign ones. The reason is that most manufacturers do not want to invest more in originals and creative advertising. Large-scale screen printing originals such as 6-inch, 8-inch, 12-inch, etc., Kodak single color reversal film shooting production. If an original manuscript is composed of creative compositions, colors, light and shadows, scenery objects, levels of reality, and themes are all excellent works of art, no matter what type of printing method is used, copies printed on it must be superb.
According to the creative design of the advertisement, the manuscript may not be photographed. Two or more photographs are required to be re-created on a computer, and the splicing is carried out. The slogan, trademark, product name, factory name, address, Phones and other implants are seamless, and tonal adjustments and local color changes are also available. Finally input all kinds of technical data: magnification, dot lines, dot type and grid angle, partition plate data, etc. After confirmation, store and print color samples, submit customer verification, confirm or modify the information The data is input to the hard disk, which is sent to the laser image-setter to output the color separation film, yellow Y, magenta M, blue C, black BK, four bottom plates, and if there is spot color, the color-matching bottom plate. You can make a silk screen version by getting a color separation base film.
The size of the trackable film of the laser line-arranging machine is generally smaller than that of the full-length sheet or equal to the full sheet, that is, 850×1189mm, and some outputable lengthened films may have an axial length of less than or equal to 1189, and the radial length may be extended to a decimal or integral multiple of 850. For example, the output 1010 × 3010mm film, so that for A type and letter A large screen printing is no problem.
Second, outlets, points and angles
The dots, points, and angles used in large screen printing.
The printed dot or screen mesh.
The transitional level on the printed image is formed by halftone dots. The printed dots and the center-to-center distance between the dots are equal, and the dot diameter changes according to the depth of the original tone.
The change in the center distance of the dot, that is, the number of lines of the dot, the number of lines: the number of dots in the unit length. The printing industry is accustomed to using the English system. For example, there are 150 outlets within a one-inch length called 150 lines, which are converted into 150/2.54≈60 lines per metric length of metric system. A set of printing plates M, C, B and K must be the same. The number of lines.
Dots change their diameters in the same number of lines, forming a hierarchy. The more levels, the richer the hue, the less shades of the hierarchy are compressed, and the subtle levels are lost. The tool for checking the level is the ladder ruler, the ladder ruler without the network point is called the gray ladder ruler, and the grayscale ruler is called the dot network with the dot network.
The number of outlets in the outlet is related to the viewing distance of the printed product, and has nothing to do with the color of the screen or the actual situation. Offset printing products are generally viewed at close quarters. For example, albums are viewed at bright viewing distances, and calendars are interior decorations. Therefore, offset printing uses 150 lines and 175 lines. Subtle points are almost indistinguishable from the retina and can only be seen as full color. Continuous picture.
For large screen printing, the general viewing distance must be viewed in meters or even tens or hundreds of meters. There is no need to use thin lines at all. The higher the number of lines, the more technical difficulties are related to screen printing. Big.
Type A prints, such as telephone booth advertisements, interior decoration posters, etc., use 30 lines/in (12 lines/cm), and the thick cable lines will have a freshness and a certain decorative effect.
Letter A type printing products such as roadside huge billboards with 20 lines/in (8 lines/cm) is very good. At the French Basic Science Exhibition (Beijing), a monochrome photo of a large dot line printed on a white fabric curtain measuring 6 meters long and 2 meters wide was taken by a combine harvester in Mai Lang. Is a line per inch, a 50% dot area is 1.27cm, a 100% dot is 2.54cm!
Dot type
There are many types of dots in offset printing, such as conventional cloth texture dots, elliptical dots, and chain-type dots, all of which are developed from cloth dot points and are vertically and horizontally arranged. In the electronic ink jet printing, a chaotic point type is also used. It is also regular. The basic unit is a network with a 90° angle and the top of the corner as a point, and then emits five layers, two layers and three points. The three-level five-point, the four-level seven-point, the five-level nine-point, the same point size, the same spacing, followed by the development of a full version, become a chaotic point.
Now the point type has developed art point types, such as straight lines, corrugations, wave patterns, sand spots (coarse, fine), brick patterns, etc., which are used in a large-scale monochrome screen printing and have a strong decorative effect.
Cloth pattern type is most commonly used, but it is necessary to consider the occurrence of abnormal interference patterns in the superposition of color textures and superimposition of screen meshes. The internationally-used superposition angles of various color patterns are dark angles CM, C, and BK) whose angle difference is 30°, that is, the first quadrants of coordinates are 15°, 45°, and 75°, which are called as unequal differences. Angle system, their angle difference is 15 ° -30 ° -30 ° -15 °. Our country also adopts this set of perspectives. Light color (Y) version generally uses 0 degrees. This set of angles is sufficient for offset printing, but it is not enough for silk screen printing because it solves the problem of interference between the color screen dots and the screen mesh, although it resolves the abnormal interference between the color plates.
If the two mesh textures are superimposed, an interference pattern will be found. The interference pattern changes with the size of the two mesh textures (line, mesh) and superposition angle. Through experiments, large-scale screen printing uses 250-mesh screens, and when printing 20 or 30-line screens, it is safe to use the above-mentioned conventional angles M, C, and BK dark versions for appointments of 15°, 45°, and 75°, respectively. The Y line color plate is fixed at 0°. If you change the number of screen dots and the number of silk screens, you must experiment to find the angle of the print without any abnormal interference patterns to print. The normal interference pattern is conducive to the party's transfer of color, reproduces the outline of the image, and the abnormal interference pattern destroys the color transmission and destroys the outline of the image. Care must be taken when printing.
Large screen printing can also use chaos or sand spot type. However, it is required that the dot generator of the laser photosetter has the function of generating such a point type.
Third, the screen version
The screen version of the printed color dot image should be a thin flat screen (S type). The number of meshes does not need to be too high, choose 250 mesh yellow (red) color mesh can be.
The selection of the frame should be larger in cross-section. If the cross-section is small and the strength is enough, the strain will be generated when stretched. The tension of large-scale color screen printing is very important, the four screen plates must have the same tension, and the tension is inconsistent. When printing is not overprinted, the image is empty. Under normal circumstances, the tension should be controlled between 16N/cm-20N/cm, and the tension tolerance of each color plate should be less than 0.5N/cm.
Large screen printing due to the effective squeegee area is large, and the distance between the empty nets must be increased accordingly. The distance between the empty nets should not be less than 20 to 30 cm.
Large-scale wire mesh stretch netting is preferred for mechanical lever-type large-scale stretch netting machines, followed by pneumatic (oil-pressure) large-scale stretch netting machines, and secondly manual stretch netting.
First, the manuscript
The originals of large-scale advertisements are much smaller than the finished ones, and the originals must be enlarged to be enlarged by several hundred times. Therefore, it is necessary to carefully examine the manuscript (color reversal film) with a magnifying glass of 10 times or more, and it is required that the manuscript be clear in outline, uniform in color, bright in color, and moderate in contrast. Large-scale advertising manuscripts must be carefully photographed with professional photographic equipment and professional advertising photo technicians. Printing is the copying of a manuscript, and the copy is not overwritten. We always say that China's printed matter is not as exquisite as foreign ones. The reason is that most manufacturers do not want to invest more in originals and creative advertising. Large-scale screen printing originals such as 6-inch, 8-inch, 12-inch, etc., Kodak single color reversal film shooting production. If an original manuscript is composed of creative compositions, colors, light and shadows, scenery objects, levels of reality, and themes are all excellent works of art, no matter what type of printing method is used, copies printed on it must be superb.
According to the creative design of the advertisement, the manuscript may not be photographed. Two or more photographs are required to be re-created on a computer, and the splicing is carried out. The slogan, trademark, product name, factory name, address, Phones and other implants are seamless, and tonal adjustments and local color changes are also available. Finally input all kinds of technical data: magnification, dot lines, dot type and grid angle, partition plate data, etc. After confirmation, store and print color samples, submit customer verification, confirm or modify the information The data is input to the hard disk, which is sent to the laser image-setter to output the color separation film, yellow Y, magenta M, blue C, black BK, four bottom plates, and if there is spot color, the color-matching bottom plate. You can make a silk screen version by getting a color separation base film.
The size of the trackable film of the laser line-arranging machine is generally smaller than that of the full-length sheet or equal to the full sheet, that is, 850×1189mm, and some outputable lengthened films may have an axial length of less than or equal to 1189, and the radial length may be extended to a decimal or integral multiple of 850. For example, the output 1010 × 3010mm film, so that for A type and letter A large screen printing is no problem.
Second, outlets, points and angles
The dots, points, and angles used in large screen printing.
The printed dot or screen mesh.
The transitional level on the printed image is formed by halftone dots. The printed dots and the center-to-center distance between the dots are equal, and the dot diameter changes according to the depth of the original tone.
The change in the center distance of the dot, that is, the number of lines of the dot, the number of lines: the number of dots in the unit length. The printing industry is accustomed to using the English system. For example, there are 150 outlets within a one-inch length called 150 lines, which are converted into 150/2.54≈60 lines per metric length of metric system. A set of printing plates M, C, B and K must be the same. The number of lines.
Dots change their diameters in the same number of lines, forming a hierarchy. The more levels, the richer the hue, the less shades of the hierarchy are compressed, and the subtle levels are lost. The tool for checking the level is the ladder ruler, the ladder ruler without the network point is called the gray ladder ruler, and the grayscale ruler is called the dot network with the dot network.
The number of outlets in the outlet is related to the viewing distance of the printed product, and has nothing to do with the color of the screen or the actual situation. Offset printing products are generally viewed at close quarters. For example, albums are viewed at bright viewing distances, and calendars are interior decorations. Therefore, offset printing uses 150 lines and 175 lines. Subtle points are almost indistinguishable from the retina and can only be seen as full color. Continuous picture.
For large screen printing, the general viewing distance must be viewed in meters or even tens or hundreds of meters. There is no need to use thin lines at all. The higher the number of lines, the more technical difficulties are related to screen printing. Big.
Type A prints, such as telephone booth advertisements, interior decoration posters, etc., use 30 lines/in (12 lines/cm), and the thick cable lines will have a freshness and a certain decorative effect.
Letter A type printing products such as roadside huge billboards with 20 lines/in (8 lines/cm) is very good. At the French Basic Science Exhibition (Beijing), a monochrome photo of a large dot line printed on a white fabric curtain measuring 6 meters long and 2 meters wide was taken by a combine harvester in Mai Lang. Is a line per inch, a 50% dot area is 1.27cm, a 100% dot is 2.54cm!
Dot type
There are many types of dots in offset printing, such as conventional cloth texture dots, elliptical dots, and chain-type dots, all of which are developed from cloth dot points and are vertically and horizontally arranged. In the electronic ink jet printing, a chaotic point type is also used. It is also regular. The basic unit is a network with a 90° angle and the top of the corner as a point, and then emits five layers, two layers and three points. The three-level five-point, the four-level seven-point, the five-level nine-point, the same point size, the same spacing, followed by the development of a full version, become a chaotic point.
Now the point type has developed art point types, such as straight lines, corrugations, wave patterns, sand spots (coarse, fine), brick patterns, etc., which are used in a large-scale monochrome screen printing and have a strong decorative effect.
Cloth pattern type is most commonly used, but it is necessary to consider the occurrence of abnormal interference patterns in the superposition of color textures and superimposition of screen meshes. The internationally-used superposition angles of various color patterns are dark angles CM, C, and BK) whose angle difference is 30°, that is, the first quadrants of coordinates are 15°, 45°, and 75°, which are called as unequal differences. Angle system, their angle difference is 15 ° -30 ° -30 ° -15 °. Our country also adopts this set of perspectives. Light color (Y) version generally uses 0 degrees. This set of angles is sufficient for offset printing, but it is not enough for silk screen printing because it solves the problem of interference between the color screen dots and the screen mesh, although it resolves the abnormal interference between the color plates.
If the two mesh textures are superimposed, an interference pattern will be found. The interference pattern changes with the size of the two mesh textures (line, mesh) and superposition angle. Through experiments, large-scale screen printing uses 250-mesh screens, and when printing 20 or 30-line screens, it is safe to use the above-mentioned conventional angles M, C, and BK dark versions for appointments of 15°, 45°, and 75°, respectively. The Y line color plate is fixed at 0°. If you change the number of screen dots and the number of silk screens, you must experiment to find the angle of the print without any abnormal interference patterns to print. The normal interference pattern is conducive to the party's transfer of color, reproduces the outline of the image, and the abnormal interference pattern destroys the color transmission and destroys the outline of the image. Care must be taken when printing.
Large screen printing can also use chaos or sand spot type. However, it is required that the dot generator of the laser photosetter has the function of generating such a point type.
Third, the screen version
The screen version of the printed color dot image should be a thin flat screen (S type). The number of meshes does not need to be too high, choose 250 mesh yellow (red) color mesh can be.
The selection of the frame should be larger in cross-section. If the cross-section is small and the strength is enough, the strain will be generated when stretched. The tension of large-scale color screen printing is very important, the four screen plates must have the same tension, and the tension is inconsistent. When printing is not overprinted, the image is empty. Under normal circumstances, the tension should be controlled between 16N/cm-20N/cm, and the tension tolerance of each color plate should be less than 0.5N/cm.
Large screen printing due to the effective squeegee area is large, and the distance between the empty nets must be increased accordingly. The distance between the empty nets should not be less than 20 to 30 cm.
Large-scale wire mesh stretch netting is preferred for mechanical lever-type large-scale stretch netting machines, followed by pneumatic (oil-pressure) large-scale stretch netting machines, and secondly manual stretch netting.
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