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Perfect printing technology improves the collection value of stamps in an all-round way (I)

stamps are a special kind of printed matter that most of us will contact and use. In addition to its function as securities, many stamps (especially rare stamps) are still high-value artworks and collections. Stamps are full of rich ornamental and scientific features. They have the infinite charm of collecting all over the world through the ages. They have high collection value. In addition to the provisions of the standard, and with the passage of time, the collection volume continues to decline and continue to appreciate. Therefore, stamp printing requires not only exquisite pictures, but also considerable anti-counterfeiting technology. Now, with the continuous development of anti-counterfeiting technology, the anti-counterfeiting technology content of stamp printing has also increased. Therefore, the printing of stamps is different from the printing of general books and advertisements

plate making technology

at present, the printing of stamps is mainly gravure printing (some of them are printed with relief and offset), which is mainly to ensure its seriousness and authenticity. China's stamps generally also use gravure printing. Gravure printing is a printing method that transfers graphics and texts below the layout to the substrate. The gravure printing method is used to print many tickets, such as banknotes and stamps, with clear dots and lines, clear layers, thick ink layers, good hand feel and strong anti-counterfeiting. Therefore, its quality is recognized

there are many techniques for making gravure. In terms of engraving and plate making, in addition to hand engraving, there are many engraving methods, such as machine engraving, electronic engraving, laser engraving, etc. These engraving methods have their own characteristics and uses

(1) photosensitive polymer gravure. This plate is composed of subbase, photosensitive layer and protective layer. The first is to put the color separations on the plate for exposure, which is called color separation exposure. Pictures and texts are transferred to the plate, and the exposed area is polymerized into an insoluble area. Then, after deep exposure without film to control the depth, wash with water, and the part without polymerization reaction is washed away by water. After washing, conduct intermediate exposure to improve the hardness and printing resistance of the plate. Finally, expose again without film to increase stability. The printing plate is used on a gravure press composed of a printing plate cylinder, an ink scraper assembly and an embossing cylinder. It is suitable for printing gold, silver, Xu cloth pearl powder or aluminum foil, plastic film background color printing

(2) hand engraved intaglio. First, draw the pattern that needs to be printed into a sketch, and according to the sketch, carve a rich level of dots, unified patterns or words on the steel plate with a carving knife. The steel plates carved by hand are called small originals. The small original should be heat treated to improve its hardness. The graphics and texts on the small original are extruded on the steel shaft surface by the plate passing machine. After the steel shaft is hardened by heat treatment, the patterns on the shaft surface are extruded by the plate passing machine. Turn the pictures and texts on the steel plate again. This process is called "version passing". Then, press the pictures and texts on the steel plate on the 1mm thick plastic plate with a hot press. After manual revision, the plastic printing plate of a single picture is made into a large plate. The large plastic plate is used to turn the copper plate, the copper plate is used to turn the nickel relief plate, and the nickel relief plate is then turned into a nickel intaglio plate or iron intaglio plate printed on the machine for use on the machine. Hand carved intaglio is mainly used for the printing of securities (such as banknotes, stamps, etc.). However, the engraving intaglio process in stamp printing has now adopted the electronic engraving method

(3) photographic etching gravure. First, the color manuscript is separated to make a monochrome negative image. After revision, the negative image is put on the continuous shooting machine and photographed into a large positive image color separation film. The large positive image is exposed on the printing plate, and then the printing plate is corroded with ferric chloride solution. Finally, the printing plate is plated with aluminum to improve the printing resistance

gravure printing stamps have used two kinds of plate making processes, namely, the traditional gravure plate making process and the modern gravure plate making process

(1) photographic etching gravure stamp plate making process. In traditional gravure stamp plate making, the original is first photographed for color separation, and then the continuous negative image of several colors required is decomposed, and then it is manually corrected. The corrected negative image is reduced to the positive image with the same specification and size as the stamp through the photographic continuous shooting machine, and then it is patted into a positive image color plate of dozens of weights or hundreds of one page stamps, and then the printing plate is made

when making a printing plate, first sun the grid (also known as line) for gravure printing on the carbon paper, and then sun the stamp pattern (positive figure) on the carbon paper with the grid, and then transfer the adhesive film with the grid pattern on the carbon paper to the already prepared printing cylinder, and use ferric chloride solution to deeply and shallowly corrode the surface of the printing cylinder. In order to improve the printing resistance of the printing cylinder, finally, a layer of chromium should be plated on the surface of the printing cylinder for machine printing. The traditional gravure plate making process is cumbersome, slow, long production cycle, poor product quality stability, and the operation is technically difficult and difficult to master. At present, it is not used in stamp printing. With the printing industry entering the era of electronic printing, the plate making process of experimental speed gravure stamps has also been improved from traditional manual plate making to modern electronic plate making. After the transition from electronic subcontracting, turning over the milky white film to electronic engraving, it entered the stage of optical film plate making, which combines the high-end electronic color separation system with the electronic engraving workstation

the original stamp is first separated by an electronic color separation machine, and the image information after color separation is transmitted to the computer for correction. Stamp printing is different from ordinary printing. In addition to using three primary colors, it often needs to add various spot colors, so it needs to make face-to-face corrections to the page after color separation. At the same time, because the stamp face is relatively small, the pattern is exquisite, and the required quality is very high, which brings great difficulties to overprint printing, especially in high-speed printing. Therefore, during plate making, special technical treatment should be carried out on the overprint interface of various color plates to ensure the printing quality. In addition, the arrangement and placement of text and borders need to be carried out in the computer. When the layout of a stamp is completed, the operator will transmit the electronic data to the electronic engraving workstation. The electronic engraving workstation carries out and typesetting according to the data, the layout specifications of full page stamps and the layout requirements of machine printing. It also needs to smooth the edges of words and lines and make the final minor correction of the pattern. After that, dozens or even hundreds of stamp patterns with exactly the same color and level can be engraved on the electrolytic copper on the surface of the printing roller by the electronic engraving machine, and the printing roller can be printed on the machine after chrome plating

due to the use of optical film operation, the plate making process of modern photographic gravure stamps is completed at one go from the high-end coupling system of electronic color separation to the electronic engraving workstation, which improves the plate making speed, shortens the production cycle, has high overprint accuracy, good plate making repeatability, stable quality, and is conducive to the management of process digitization, standardization and even standardization

(2) plate making process of engraving gravure stamps. There are many methods of engraving gravure, such as mechanical plate passing method, electroplating plate passing method, corrosion method, etc. Our country adopts the method of mechanical plate passing. In this method, the pattern of the original stamp is first reduced to a small flat steel plate according to the specification and size of the stamp, and the engraver uses a carving knife to manually carve the pattern into dots and lines with different shapes, widths and depths on the copper plate, so as to show different levels in the picture. This carved small steel plate is used as the original plate of the engraving gravure (called the original steel plate), and then it is used to copy the printing plate for printing. Gravure stamps are printed on a rotary machine. Therefore, when making a printing plate, the original steel plate must be heat treated to strengthen its hardness, and then placed on a special plate passing machine. Through mechanical extrusion, the dots and lines with different depths on the plane small steel plate are transferred to another small steel shaft to obtain convex lines and dots; The small steel shaft is also placed on the plate passing machine after heat treatment. The above indirect measurement method can only confirm the total value of the wear on each friction surface. The pattern is transferred to the printing roller with electrolytic copper coating on the surface one by one according to the specification of a full page stamp, and the graphic points and lines that jointly promote the partners to walk out of the concave shape of the accurate and pleasing entrepreneurial trajectory in the center of the dial are obtained; After chrome plating, the printing roller can be printed on the machine, and the plate making of engraving gravure stamps is completed. Engraving gravure stamps has its unique effect. The patterns are clear-cut, the ink layer is thick, there is a slight bulge on the paper, and the extremely thin dots and lines are clear. The color and luster remain unchanged for a long time, which is conducive to putting an end to the forgery of stamps. Although the engraving gravure plate making and printing technology is very difficult, its anti-counterfeiting performance is good, so stamps all over the world are mostly printed by engraving gravure technology

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