Color separation of printing plate-making manuscript and output technology of printing plate-making manuscript
Making plate-making manuscript Plate-making manuscripts can also be called black-and-white manuscripts, color separation manuscripts, plate-making negatives, etc. Its main function is to make the photosensitive printing stencil Konica Minolta. Therefore, the plate-making manuscript must be drawn on a transparent substrate, and its image is an opaque ink layer (black or red). The transparency of the substrate and the shading density of the ink layer are the key indicators to determine the quality of the plate-making manuscript. The image of plate-making manuscript is mainly produced by hand drawing, manual or mechanical engraving, photosensitive copying, laser phototypesetting, printer Yin Gao, etc., but some ordinary paper manuscripts are treated with light transmission (such as oil) as plate-making manuscripts.
1. color separation There are two main types of color separation in T-shirt design: spot color separation and primary color separation.
Spot color separation in T-shirt design refers to the investigation of any specially prepared color as a printing color, and the color image is formed by such spot colors through overprinting. Five-color printing and twelve-color printing, which we usually talk about, refer to printing products with color images by overprinting five spot colors or twelve spot colors in turn. However, the number of spot colors is not equal to the number of colors in an image, because spot colors can also be overprinted, so five spot colors can also print six sets or even seven colors and eight colors. Spot color printing is mainly used for digital printing of color block printing, and its reflection on natural scene can only be simulated rather than restored, which is the biggest difference from primary color printing. However, with the development of screen printing technology and new ink, spot color screen printing has sprung up in recent years. Especially in T-shirt printing, the most advanced T-shirt printing technology with the latest international T-shirt pattern is not primary color printing but spot color screen printing for wine packaging, that is, multi-color spot color screen printing on color, especially black T-shirts. Printability Primary color separation refers to the decomposition of natural color images into three primary colors (magenta, cyan and yellow), so as to carry out three primary color tone printing to restore the object image. Any color in nature is composed of three primary colors, so in theory, a vivid restored image can be printed by using three color plates: cyan, magenta, yellow and yellow. However, due to various factors, three primary color prints are difficult to achieve this point. Therefore, in printing practice, four-color printing is usually adopted, that is, three primary colors plus black. In recent years, in order to restore color ink supply more realistically in the world, six-color printing and seven-color printing have been developed on the basis of four-color printing. The principle is to separate composite colors such as orange, purple and green on the basis of four colors, so as to reduce the gray scale in printing and achieve high fidelity. In order to distinguish it from spot-color printing, we usually refer to the reductive printing of natural color patterns by optical or digital technology as primary color printing (which can be understood as reductive color printing), which is different from the concept of primary colors (only three primary colors) in optics and colorimetry.
It is worth mentioning here that primary color printing is not incompatible with spot color printing. In the international printers’ tour, the latest development of color printing is the combination of primary color and spot color for special primary color printing, which brings their strengths into play, brings out the best in each other, has a higher printing effect, and belongs to high-quality printing. This has also been allowed to play in T-shirt printing. I have seen an American-made T-shirt with 12-color printing in total. Besides the four primary colors, it is also equipped with eight sets of spot colors, among which besides gold and silver, there are especially foaming printing and crystal paste printing. The effect is not only strong in stereoscopic impression, but also the special parts are shiny and digital publishing, which is really amazing. chromatography Professional T-shirt designers generally design and compose according to the principle of spot color or primary color, and only need to perform color separation according to their requirements after obtaining such design draft. However, there are also some non-spot designers or customers who only provide all kinds of pictures or drawings and other manuscripts to be printed on T-shirts. In this case, we need to communicate with designers and customers: first of all, we need to understand their creative intentions and what effect they want to express. Is it better to use spot color printing or primary color printing to achieve this effect? Even special primary color printing? At this time, t-shirts with different printing methods should be provided for them to understand and choose; Secondly, we should tell them the production and processing costs of spot-color printing and primary-color printing, so that they can make decisions according to their investment plans.
2. Color separation and plate making Color separation plate-making draft is used for photosensitive production of corresponding color separation screen printing plates. The quality requirements are as follows: first, the substrate has good light transmission performance; second, the image has high shading density; third, the alignment and color registration accuracy between the color separation sheets should be accurate; and the edges of image lines should be bright and clean, and the dots should be full and clear.
(1) The reticle is generally used for positioning multi-color separations. However, it is easy to put the separations in reverse in the process of printing, or the front and back are wrong, or the graphics are upside down. We use the method of Zuo Zheng’s right oblique to position the reticle, that is, the left side is+,and the right side is X carton, thus eliminating mistakes.
(2) Because red tear film is expensive and not easy to buy, it can be replaced by red self-adhesive paper. As long as you stick the red self-adhesive only on the PVC film (which is duplicated on the original manuscript or line manuscript), you can engrave it with a carving knife. Since the light transmittance of red self-adhesive paper is far less than that of red tear film, the light of drawing table should be brighter. In this way, wine packaging can achieve low price, good shading effect, smooth lines, no fear of water and humidity, and even better, it is convenient to modify-just remove it and re-engrave it, while red tearing is a Shanghai grand scene that cannot be re-engraved, and ink painting can only be modified slightly. Printing market (3) If the patterns of the two printing plates are not connected or overprinted, it is considered to draw two color manuscripts on one film. When printing, two plates are made, with the A plate enclosing the B pattern and the B plate enclosing the A pattern. You can even make a plate in the sun, add an ink barrier between AB patterns for CD printing, and use a plate to print two colors at the same time.
3. Manufactured manuscripts by hand Manufacturing manuscripts is the most basic traditional method, mainly for manual drafting and manual engraving.
Manual manuscript making tools mainly include: light drawing table (OA table), drawing ink pen, drawing compass, triangle, curved plate, paper cutter, steel ruler, drawing PVC film, PCV film drawing ink, red tear film, red self-adhesive paper, etc.
For manual drafting of T-shirt design, first of all, there should be a light drawing table, and the light source is generally fluorescent lamp. If incandescent lamp prepress process is adopted, frosted glass should be used or a layer of copying paper should be pasted under the glass, so that the light is softer and does not hurt eyes. If you need to draw pictures at home or in a temporary field, the emergency measures are to put the square stool on the ground upside down, put a piece of glass on the legs of the four stools, and put a table lamp under it for beverage packaging.
Drawing ink pens are mostly needle pens, with a pen tip diameter of 0.2 ~ 1.3 mm. To prevent the pen from blocking, you can put a hollow cotton (or sponge, etc.) in a bottle, add half a bottle of water, and insert the pen into the bottle when the drawing pen is stopped, so that the pen will no longer be blocked.
Steel ruler is used for engraving red tear film and self-adhesive paper. When drawing with triangle, curved plate, etc., the hypotenuse should face down to avoid ink being dragged by ruler.
General drawing ink can’t be used for drawing film newspaper printing, because it is slow to dry, poor in fastness, and dissolves in water and returns to moisture in rainy days. It is best to use special film drawing ink for drawing PVC membrane. If you can’t buy it for a while, you can also use Yidege ink instead, but you need to boil it for thickening. When painting large area graphics with Yidege ink, pay attention not to make the ink layer too thick, so as to avoid dryness. offset printing Be sure to wash your hands with soap and print books and periodicals before painting manuscripts by hand, because the grease on your hands will affect the painting and coating of ink.
According to the size used and the overprint sequence. Printing mucilage has hiding power, so the graphic contact lines of various manuscripts can be overprinted, and even light-colored manuscripts can be used as the background color of dark graphics. If the color of the fabric is dark, you can consider playing on a white background. The drawing sequence of the color separation draft in mucilage printing is just opposite to its printing process, that is, first draw a dark draft digital printing machine, then draw a light draft, and finally draw a white draft.
Water slurry is mainly used for printing white T-shirts, which is a transparent printing coating. Therefore, the overprint of color separation manuscripts according to the touch line is 1 ~ 2 mm. If there is too much overprint, the composite color of two-color overprint will easily appear. The drawing sequence is to draw the color draft with contour line (usually black) for investment and purchase, and then draw the draft from light color to dark color based on this diaphragm.
The color separator of foam printing plate should leave room for expansion of foam pulp, with high foam of about 1 ~ 2 mm and low foam of about 0.5 ~ 1.0 mm.
The basic requirement of manual painting (engraving) is that the lines are smooth, smooth and bright. Generally, the painted ink manuscript must be trimmed with a carving knife, especially at sharp corners.
4. Digital drafting by computer With the development of computer technology and production, computer digital design, drawing and drafting have become quite popular in China. Compared with manual drafting and photographic drafting, it has the advantages of higher quality, faster speed, more convenient production and lower cost, especially its color separation and screening quality far exceeds the level of manual and photoelectric production, and has become a widely used production method. Excessive packaging A series of work color management, such as T-shirt pattern design, color separation, screening and film production, must be completed by operating professional graphic design software and publishing software. General-purpose software, such as AdobeLIIustrator, photoshop, CoreIDraw, etc., is mainly used for the design and production of images and characters, but it will be more convenient to use domestic professional screen printing and publishing software, such as Wenyuange and Mengtai.
The program of digitizing T-shirt pattern by computer is generally as follows: graphic input-design and editing-producing effect color manuscript-color separation-screening-setting screening angle-output. If you hand it over to professionals, you must tell some technical requirements: First, the color separation intention. Whether it is primary color separation, spot color separation or special primary color separation, etc., must be made clear to the producers. Second, screening. The screening of T-shirt printing is generally below 60 lines, and the limit of screening lines depends on the production characteristics of printing materials, fabric texture and color and other factors. Gum printing is usually not suitable for screening printing reports. In special cases, screening printing technology is adopted, and the number of screening lines should be below 40 lines. Generally, the number of screening lines for water paste printing is about 50 lines. The screening line number of hot melt ink can be selected between 35 ~ 60 lines. If the fabric color is dark, the screening line number of 35 ~ 45 can be used to make the printing ink have stronger covering power. The screening line number of foaming ink and crystal ink should be thick rather than thin, and the number of lines with white background should be thicker than that of other printing colors. Because of the never-plugging feature of hot melt ink, 70-80 line screen printing can also be used. The dot pattern of T-shirt printing is usually oval and round. Third, the screening angle of T-shirts is generally 15′, usually starting from 5′. Start the screening angle of the seventh color every 20′ (still 15′). Four, especially to draw the attention of the producers, to produce Zhengyang film, that is, the positive positive picture, which is different from the usual printed version. Excessive packaging Main methods of output (1) the printer draws the manuscript. Inkjet printers, laser printers and wax spray printers can all be used. Laser printers have higher purchase cost but lower use cost. Inkjet printers have lower purchase cost but higher ink use cost, and wax spray printers (also called dry printers) have higher purchase cost and use cost. As far as the quality of drawing film is concerned, wax jet printer is the best, laser printer is also good, and inkjet printer is poor.
(2) Engraving by engraving machine. That is to say, the computer engraving machine is used to engrave the pattern on the red (black) self-adhesive paper and then stick it on the PVC film. However, the engraving accuracy of the engraving machine is not as good as that of the printer CTP, and it can only be used for printing with low registration accuracy.
(3) Laser phototypesetting. Laser phototypesetting is the method of making film with the highest quality. Just because the laser phototypesetting equipment is quite expensive, only the plate-making center with a certain scale will be configured, so the edited software is generally sent to the plate-making center to produce films. The price is higher than that of the printer, but the quality is much better.