Understanding of the front-end production of gravure plate-making
From the variety of styles and colorful packaging, it can be found that the current product packaging has not only pursued practicality and commerciality, but also its artistic nature cannot be ignored. As the mainstream technology of packaging printing, gravure printing, especially gravure platemaking, should also strengthen communication and develop simultaneously with packaging. This article only shares some of the experiences I have summarized in the pre-press production of gravure platemaking with my peers. Classification of plastic bags There are many types of plastic packaging bags, and the specifications are uncertain. Therefore, design and production staff often neglect the way of making bags. The result is that although the design draft is beautiful, the finished product packaging is unsatisfactory, and even becomes a waste product. Experience tells us that only on the basis of understanding the types of commonly used packaging products can we fully develop the design ideas, eliminate design works that do not conform to the bag-making process, and design practical and perfect finished packaging. Plastic packaging bags can be divided into four categories: three-side seal, mid-bottom seal, three-dimensional middle seal and sheet material according to the method of making bags. The three-side seal is sealed around the packaging bag. The front and back dimensions are the finished size. It has a certain sense of overallity. The design is not constrained, and the front and rear designs have a certain consistency. Because the front and back dimensions are the same, the front can be designed first so that the back and the front echo. When making a plate, the front and back should be arranged on the same set of plate rollers. The midsole seal is sealed on the back, the front size is the finished size, the back is divided into two equal parts, and the sum of its width is equal to the width of the front, usually when designing, the front and back are unfolded, integrated design, and left and right Add 1cm edge banding each, and the front and back are also on the same set of plate rollers. The three-dimensional middle seal is based on the middle bottom seal, and three-dimensional edges are added on both sides, and the front and back sides are also on the same set of plate rollers. Due to the limitation of printing materials, the front and back sides of the sheet must be designed separately, and the plates should be made separately. They cannot appear on the same set of cylinders at the same time. Color design basis and color specification Because plastic printing is different from paper printing, in order to print bright and bright packaging, you need to understand the color characteristics of plastic printing when designing the color at the front end. First of all, it is necessary to see the process sheet clearly, understand the customer's intention and the color requirements, and clarify the printing requirements of the subsequent process. (1) Substrate Understand whether the substrate is film, PA nylon film or heat-sealed film. Set the appropriate tone value. It should be noted that the color and gradation of the Indian printing are better than the surface printing. (2) Ink characteristics The printing color sequence of the Indian ink is dark first and then light, and the surface printing ink is light first and then dark. To master the performance of various inks, clarify the color shift characteristics of various inks. Generally, magenta ink has good color rendering; blue ink is more magenta; yellow ink has better brightness, but it is easy to paste, usually need to reduce the tone value by 5% -8%. Color processing points 1. Line version A considerable part of gravure printing is line printing. Line printing is composed of lines and solid color blocks. It wins by modeling, and creates visual impact with solid (special color) to highlight the advantages of line printing. According to the characteristics of the gravure printing machine, the printing plate generally does not exceed 6 colors, and the spot color should be used as much as possible, and the color mark should be matched to facilitate the color matching during printing. A set of line version can form a series of products with many different combinations. When designing, you can first design a color matching scheme for users to choose. Since the line version does not have a sense of layering, attention should be paid to the overlapping treatment between colors to meet the overprinting requirements caused by the expansion and contraction of the substrate. 2. Mesh version The mesh version has extremely rich layers and ever-changing colors, but no matter how complex the layers are, they are composed of cyan, magenta, yellow, and black (special colors need to be added with special colors). The tone levels of the image are divided into Highlight, dark tone, and middle tone. Therefore, we must first know the gray balance data of the four-color ink and the printability of each layer, grasp the rule of dot change, and summarize the image layer processing method to make the product achieve the best visual effect. (1) Adjustment of gray balance (2) Setting of tone value of highlight and bright tone area For the highlight part, one is to adjust the three primary colors of the extreme highlight to 0, as the brightest part of the image tone, and the range of the highlight part can be enlarged if necessary; the second is to adjust the highlight white area that needs gradation to the smallest printable tone The value is determined according to multiple test proofs, and the minimum dot value is C6%, M5%, and Y5%. (3) Intermediate tone level processing Midtones are the top priority of the entire image. The middle tone level should achieve the best visual brightness. To this end, it can deepen its overall saturation or reduce the saturation according to the situation, but try not to affect the gray balance of the image, and only make local adjustments to the image. For example, a plate of fruit with bright colors can grasp the main colors of different fruits when processing, appropriately reduce green leaves to red, appropriately add red to red fruits, and reduce blue and red to yellow fruits. However, after the local area is locked, the micro-adjustment of the layers and colors should be carried out to make the product color cleaner, brighter and more pleasing. (4) Dark tone level processing In general, gravure printing is very poor in the level of 80% of the Internet access area. In this way, the layers of the deepest part and the second deepest part of the dark tone need to be pulled apart, and the level of the second deepest part is reduced to about 60%. [NextPage] Overprint processing between color plates Since plastic film materials are more flexible than paper, overprinting between color plates is a link that must be considered in the production of gravure front ends. The standard of the overprint processing is as follows. (1) The text version is usually black, and it is not allowed to cut out when overprinting. If the text version is other colors, such as magenta, you can consider whether to overprint with the background color according to the size of the word. When the word is less than 12 pounds, it must be overprinted with the background color, but it still needs to consider whether the color of the text after the color overlay is eye-catching. If it affects the recognition effect, consider changing colors. (2) When the light color and the dark color are connected, the light color expansion value is generally set to 1 ~ 2PIXS. For larger layouts, the value can be increased appropriately. (3) When the spot color version is connected to the picture, the edge of the spot color version can be expanded without affecting the edge pixels of the picture. The value of the edge expansion is usually 1 ~ 2PIXS. (4) If printing opaque inks, such as gold ink, the printing sequence of the ink should be considered first, otherwise the gold ink will cover the relevant colors. If you have to do overprinting, you should also consider the problem that gold ink and other color inks will become dark and not bright when overprinting. (5) Silver ink is also a special ink, and light silver has certain transparency. Therefore, when using silver ink, it is necessary to determine whether the background color or related color is overprinted or hollowed out through design according to customer requirements. Conclusion Plastic gravure platemaking is more cumbersome than paper gravure platemaking, and there are many influencing factors. Designers should have a certain color knowledge, understand the printing process, and grasp the characteristics of platemaking to design high-quality product packaging quickly and well. 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