The stamp is a special kind of printed matter. In order to ensure its seriousness and anti-counterfeiting, the stamps in our country are generally made of concave stamps. The continuous development of anti-counterfeiting technology, the increase in the amount of anti-counterfeiting stamps printed, and the means of diversification, therefore, There are still some stamps in China that use offset printing. Given that there is not much difference between the printing process of offset stamps and general offset printing, this article will not elaborate in detail.
The printing process of gravure stamps is as follows:
First, the version of the film version (photogravure) stamping process China's shadow edition has adopted two kinds of stamping process, the traditional gravure plate making process and the modern gravure plate making process.
The traditional photocopying version of the stamp plate-making process first divides the manuscripts into photo-colors, decomposes out the necessary frontier shades of a few colors, and then artificially corrects the negative pictures through the connected photo-shooting machine - reducing the various color versions to The positive image is the same size as the stamp, and it is used to produce a positive color version of tens or hundreds of full-size stamps, followed by printing. When the printing plate is made, the gravure grid is also called a net line and sunrayed onto the carbon paper. Then the stamp pattern (positive figure) is also sunrayed onto the existing grid carbon paper, and the carbon paper is then provided with a net. The adhesive film was transferred to the already-printed Tongren Road, and shallow corrosion of the seal was performed with a ferric chloride solution. In order to improve the durability of the printing cylinder, a layer of chrome is finally plated on the surface of the printing cylinder for printing on the machine. The traditional gravure plate making process is cumbersome, slow in speed, long in production cycle, and poor in product quality stability. It is technically difficult to handle and difficult to master. Currently, stamp printing has not been adopted.
With the printing industry stepping into the era of electronic printing, the makers of our car-printed stamps have been improved from traditional hand-made plates to modern electronic plates. After the transition of electronic color separation-copying and white-printing-electronic engraving, it entered the filmless plate-making stage of the electronic color separation high-end networking system and the electronic engraving workstation.
The stamp manuscript is not transmitted to the Apple computer by the electronic color separation machine for image information after separation and separation, and correction and editing are performed. Stamp printing is different from ordinary prints. In addition to the use of three primary colors, it often needs to be added to each spot color, so it needs a layout after separation. At the same time, since the stamps are relatively small, the patterns are delicate, and the quality required is very high. This brings great difficulties for overprinting during printing, especially during high speed printing. For this reason, special technical processing is also required for the overprinting interface of various colors in order to ensure the printing quality and layout of texts and borders. Placement and similar jobs all need to be done on an Apple computer. When the layout of a stamp was completed, the operator transmitted its electronic data to the electronic engraving workstation. The electronic engraving workstation edits and typesets according to the layout specifications of the full-page stamps and the requirements of printing on the machine. It also needs to polish the edges of the letters and lines and finish the pattern finely. Afterwards, the electronic engraving machine can be used. On the electrolytic copper on the surface of the drum, dozens or even hundreds of stamps with the same level of color are engraved as required. The cylinder can be printed on the machine after chrome plating.
Since the film making process of modern shadow-printed stamps is based on the use of filmless operation, the high-end electric networking system and the electric carving workstation can be used at one go, improving the system, production cycle, high accuracy of plate printing, good plate making, and stable quality. The process of data, standardization and even standardized management and training of young technicians.
Second, the engraving process engraving gravure stamp engraving engraving gravure platemaking methods are many, such as: mechanical printing plate method, electroplating plate method, corrosion method, etc., China is the mechanical version of the law. First, the pattern of the stamp manuscript is reduced to the size of a flat steel plate according to the size of the stamp. The engraver uses a cutting Knife to manually engrave the pattern into different points, lines and lines of different shapes, widths, and depths. This shows different levels in the picture. This small piece of carved steel is used as the original version of the engraving gravure (called the original steel plate), and it is used to make the printing plate. Gravure stamps are printed on a rotary machine. Therefore, when making a printing plate, the original steel plate must first be heat-treated to enhance its hardness. Then the main machine is used to machine the plate, and the depth of the small steel plate is not affected by the mechanical press. One of the points and lines is transferred to the other small steel shaft. It is to the protruding lines and points. The small steel shaft is also heat-treated and placed on the plate press. The above pattern is stamped with the specifications of the full-page stamp. One piece was transferred to the surface of the cylinder plated with a layer of electrolytic copper, and a concave pattern point and line were obtained. After chrome plating, Indo-Den could be printed on the machine, and the engraved concave plate was completed.
The engraving and gravure stamps have their unique effects: a distinct, thick ink layer, a slight bulge on the surface of the paper, fine points, lines that are clear and definable, and constant color and color, which are conducive to the elimination of stamp reliance. Although it is difficult to engrave the gravure plate and printing technology, its anti-counterfeiting performance is not made, so most of the world's banknotes, stamps, securities, etc. are printed using the intaglio technique.
Third, the printing of the stamp gravure stamp uses a special gravure printing machine, there are four-color, five-color, six-color stamp printing machine, a color engraving intaglio plus five color shadow or four color overprinting shadow gravure Stamp printing machine. These special stamp printers are equipped with counting numbers, perforations and cutting devices. Stamps can be printed and punched on the side of the stamp, and the entire stamp can be cut to size.
The gravure gravure printing ink is a solvent-based liquid ink. When the printing plate is soaked in the ink 2, the ink on the non-graphic part of the plate is scraped off by the squeegee, and the graphic part is accompanied by the printing. In some cases, the ink is stored. After being impressed by the embossing roller, this part of the ink is transferred to the paper and multi-color overprint. A fine stamp is on the paper.
The printing ink used for the engraved version of the stamp is a cohesive resin ink. Its ink transfer form is similar to that of a printing process. However, since the graphic portion of the engraving gravure is concave, the non-printed (flat) ink on the printing plate is Wipe with the ink wiper. At present, there are roughly four types of ink wipes for engraving and printing: cloth wiper, trichloroethylene wiper, water wiper, and paper eraser. Rubbing the ink with a cloth, the ink level and gloss of the printed ink are printed, but the printing speed is slower; the printing speed of the trichloroethylene ink is faster, but the toxicity is great, which is harmful to the human body; the water ink is a relatively advanced one. Wiping method, but there are also problems of wastewater treatment and pollution; paper rubbing ink is suitable for small-volume printing, and is not suitable for such large-volume stamp printing in China. China's engraving stamp printers are equipped with cloth rubbing devices.
In addition to the single gravure ticket or single engraving ticket mentioned above, the gravure stamp has a type of postage stamp that is overprinted and engraved, known as the shadow carving stamp. It is most favored by stamp collectors. The printing of shadow carving stamps overprints the different combinations of printing methods in the concave carving grooves. It is difficult for the older generation to print valuable securities with an ideal process, but it is difficult to surface with rich colors and delicate layers; photogravure also has its disadvantages. Since some stamps are empty, the amount of ink required for printing is large, and the gravure ink is The viscosity of the fluid is very small, so the owner displays irregular water marks at the depth of the recording, destroying the delicateness of the stamp image; A zigzag shard appears at the edge of the thin line or text, which affects the smoothness of the printing effect. In order to make the stamps more perfect, we use a combination of engraved intaglio and photogravure printing to exert the respective strengths of the two printing methods to achieve better printing effects, such as the famous Huangshan scenery, Lushan scenery, and the Lunar New Year stamps. In addition, stamps such as Chinese ancient towers, Laoshan, and rare birds issued in recent years have been printed in this way.
Combining two different printing methods with different properties, the process, especially the overprinting accuracy, is very difficult. The printing pressure required by each of them is completely different, and the ink properties are also different. There are also requirements for the printability of the paper. Therefore, the mechanical error in printing is large, and the rejection rate is also higher than other printing methods. When designing the printing process of such stamps, it is necessary to fully understand and utilize the characteristics of these two printing methods, and to avoid weaknesses in order to obtain better printing results. This type of overprinted version of the stamp is generally based on the engraving version, to make a picture pattern rendering effect, and then lined with photo gravure smudge color. Therefore, sculpting the main lines and ideas should be based on the fact that the outline image of the pattern and the main level; the color of the photogravure lining can be shallow, imaginary, auxiliary color changes in the details of the color and level, so that even if there are mechanical errors will not cause The contours of the subject are clear and complete. The stamps on the printed figures are tall and straight, with prominent themes, strong sense of three-dimensionality, and magnificent colors. They have very unique artistic effects, and are especially worth collecting for stamp collectors.
At present, international stamps are mostly printed on engraving and offset printing. The modern offset printing technology greatly improves the ability to express colors and layers. The text and lines of the offset printing are clear and smooth, the background color is uniform and thick, the pattern colors are elegant and harmonious, and the engraving lines, the ideas, and the artistic effects of the stamps are overprinted. It is more perfect.