Understanding of the front end of gravure plate making
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From the various styles and colorful packaging, we can find that the current packaging of goods has not only pursued practicality and commerciality, but also its artistic nature can not be ignored. As the mainstream technology of packaging printing, gravure printing, especially gravure printing, should also strengthen communication and develop in parallel with packaging. This article only shares some of the experiences I have summarized in the pre-press production of gravure printing, and shares and learns with my peers.
Plastic bag classification
There are many kinds of plastic packaging bags, and the specifications are uncertain. Therefore, the design and production staff often neglect the bag making method. As a result, although the design draft is exquisite, the finished packaging is unsatisfactory and even becomes a waste product. Experience tells us that only by understanding the types of commonly used packaging products can we make full use of 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 three types: three-side seal, mid-bottom seal, three-dimensional middle seal and sheet material according to the bag making method.
The three-side seal is sealed around the packaging bag. The size of the front and back are finished products, which have a certain overall sense. The design is not constrained, and the front and rear designs have certain consistency. Since the front and back dimensions are the same, you can design the front side to match the back and front. When making plates, the front and back should be arranged on the same set of rollers.
The midsole seal is sealed on the back, the front dimension is the finished size, the back is divided into two equal parts, and the sum of the widths is equal to the width of the front side. Usually, the front and back sides are unfolded during design, and the design is integrated. Each 1cm edge is added, and the front and back are also on the same set of rollers.
The three-dimensional middle seal is based on the middle bottom seal, and the three-dimensional side is added on both sides, and the front back and the side three sides are also on the same set of cylinders.
Due to the limitation of printed materials, the front and back sides of the sheet must be designed separately and separately, and cannot be simultaneously displayed on the same set of cylinders.
Color design basis and color specification
Since plastic printing is different from paper printing, in order to print a bright and elegant package, it is necessary to understand the color characteristics of plastic printing when designing the color of the front end. First of all, we must see the process list, understand the customer's intention and its requirements for color, and clarify the printing requirements of the post-process.
(1) Substrate
To understand whether the substrate is a film, a PA nylon film or a heat sealing film, set a suitable tone value. It should be noted that the color and level of the printing are better than the surface.
(2) Ink characteristics
The printing color sequence of the printing ink is first deep and shallow, and the printing ink is shallow and deep. To master the performance of various inks, the color shift characteristics of various inks are clarified. Generally, the magenta ink has good color rendering; the blue ink has a magenta color; the yellow ink has a good brightness, but it is easy to paste, and the gradation value is usually reduced by 5% to 8%.
Color processing points
Line version
A considerable part of the gravure printing is line printing, and the line version is composed of lines and solid color blocks to win the shape and create a visual impact in the field (special color) to highlight the advantages of the line version. 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 code should be matched to facilitate the color matching during printing.
A set of line versions can be used to form a series of products with different combinations. When designing, you can design a color matching scheme for users to choose. Since the line version has no layering, color-to-color should be paid attention to the color-to-color processing to meet the overprinting requirements caused by the stretching of the substrate.
2. Net version adjustment
The mesh version has an extremely rich level and ever-changing color, but no matter how complicated the layer is composed of four colors of cyan, magenta, yellow and black (special case needs to add spot color), the tone level of the image is divided into Highlights, dark tones, and mid-tones.
Therefore, we must first know the gray balance data of the four-color ink and the printability of each layer, master the change rules of the dot, and summarize the image layer processing method to make the product achieve the best visual effect.
(1) Adjustment of gray balance
(2) High-light, bright adjustment area tone value setting
For the highlight part, one adjusts the three primary colors of the extremely high light to 0, which is the brightest part of the image tone, and can increase the range of the highlight part if necessary; the second is to adjust the high-light white area of the required level to the minimum printable level. The value is determined according to multiple test proofs, and the minimum dot value is C6%, M5%, and Y5%.
(3) Intermediate level processing
The midtone is the top priority of the entire image. The level of the midtone should be the best visual brightness, for which you can deepen its overall saturation or reduce the saturation according to the situation, but try not to affect the gray balance of the image, only local adjustment of the image. Such as a plate of bright color fruit, the main color of different fruits can be grasped during treatment, the green leaves are appropriately reddened, the red fruits are appropriately red, and the yellow fruits are reduced in blue and red. However, the part should be locked, and then the micro-adjustment of the level and color will be made to make the product color clean, smooth and pleasing.
(4) Dark tone level processing
In general, gravure is very poor at 80% of the level of the Internet access area. In this way, it is necessary to open the level of the darkest part and the second deep part of the dark tone, and reduce the level of the second deep part to about 60%.
Overprinting between color plates
Since plastic film materials are more flexible than paper, the overprinting process between color plates is a must in the production of gravure front ends. The standard for overprint processing is as follows.
(1) The text version is usually black, and when it is overprinted, it is not allowed to be hollowed out. If the text version is other colors, such as magenta, you can consider whether to overprint the background according to the size of the word. When the word is less than 12 lbs, it must be overprinted with the background color, but it is still necessary to consider whether the color of the text after the color combination is conspicuous. If the effect of recognition is affected, color change can be considered.
(2) When the light color is connected to the dark color, the value of the light-colored expanded edge is generally set to 1 to 2 PIXS. Larger layouts can be appropriately increased in value.
(3) When the spot color version is connected to the picture, the spot color version can be expanded without affecting the edge pixels of the picture. The value of the expansion is usually 1~2PIXS.
(4) If printing opaque inks, such as gold ink, the printing order 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 of darkening and not brightening when gold ink and other color inks are overprinted.
(5) Silver ink is also a special ink, light silver has a certain transparency. Therefore, when using silver ink, it must be determined by design according to customer requirements whether the background color or related color is overprinted or hollowed out.
Conclusion
Plastic gravure plate making is more cumbersome than paper gravure plate making, and there are many influencing factors. The design and production personnel should have certain color knowledge, understand the printing process, and grasp the plate making characteristics, in order to design high-quality product packaging quickly and well.