Requirements for design of packaging and printing manuscript by letterpress and offset printing (below)

2 Offset requirements for the design of packaged printing manuscripts Offset printing is the application of indirect printing in graphic reproduction. Its copied products have achieved a high level of authenticity, beauty, color, and level, and are particularly suitable for the printing of graphic and textual packaging. At present, the proportion of offset printing in packaging and printing is very large, mainly because most of our country's packaging prints use exquisite designs (mainly in color continuous originals). The effect of offset printing is the best, although gravure can also Exquisite patterns are printed, but gravure printing has a long production cycle. Plate printing costs high and is not suitable for short-run printing. The main disadvantage of offset printing is that the printing process is inseparable from water, there is a problem of ink and ink balance, and the hue of printed products is not easy to control. At the same time, due to the high speed of offset printing, large format, and low pressure, the printing of large areas of color blocks is often inaccurate, and the color is not sufficiently bright and saturated, so the offset printing process is difficult to form a thick ink layer, and the performance of color blocks is not good. Therefore, in the packaging and printing, offset printing is mainly applied to a package mainly composed of a color continuous tone original. For this reason, here we mainly focus on color continuous-tone originals and talk about the requirements for offset printing in the field of plate-making.
A color continuous-tone manuscript is a manuscript with a change in brightness and darkness (gradation), and a four-color color coded screen in a plate making. Color continuous manuscripts usually use electronic color separation, and color desktop printing systems can also be used for color separation. Most of them are mainly offset printing. Continually-tuned manuscripts in printing are mainly classified into three types: a painting manuscript, a photographic manuscript, and a secondary manuscript.
a. Drawing manuscript. Plate printing has a particularly high quality requirement for such manuscripts because continuous drawing of the manuscript is a direct electronic color separation or photo separation. Normally, no revision is performed and any traces on the manuscript will be revealed. This requires the original color of the design to be as close as possible to the physical effect, and at the same time, the modification should not be excessive, otherwise it will bring difficulties to the platemaking. In addition, also need to pay attention to the size limit of the electrical extension, continuous adjustment of the color of the original are mostly in the electrical extension of the liquid cartridge on the separation, so the original size should not exceed 4 open, and should be drawn with soft and curly material, otherwise Photographs should be used to photograph the original, reversal film, or photo.
In the packaging printing process, the color continuous adjustment manuscript is made of red, yellow, blue, and black four-point color plate making, through the four-color dot size ratio to represent the ever-changing colors, in the offset printing to print a single hue, generally It is also expressed in different proportions of four-color dots. According to this, there is basically no restriction on the setting of color rhyme for a color continuous tune original, but the design principle of concise, convenient printing, and less wins should be adhered to; however, for lines, texts, and other line drawings, the manuscript should be reduced. The color is not accurate, but it is still necessary to make careful coloring. Such as small text to try to use a monochrome expression; in the need for multi-color printing of small text or pattern as much as possible with the missing words, because the overprint is not likely to make the text or pattern blurred. In addition, the pictures that need to be processed must be appropriately enlarged to avoid unnecessary white edges during the trimming process.
b. Photography manuscript. As an important form of visual art, photography has become an important means for the design of packaging and printing manuscripts. Whether the quality of a photographic manuscript meets the requirements for plate printing will determine the final effect of the print. The requirements for photographic printing on photographic originals are: color photography originals should have high definition, rich layers, complete picture, moderate density contrast, no other serious defects, etc.; at the same time in the color standard, level, sharpness, granularity, original size The choice of other aspects should pay attention to the requirements of plate printing. The black-and-white photography manuscript should have clear outlines, rich layers and moderate contrasts. Especially in the control of high and low levels, the objective constraints of plate printing should be considered. The shade of manuscript in the printing is reflected by the size of the dot. In the process of plate making, due to the effect of light when the film is copy-printed, the dots are easy to run at both ends (this happens when the amount of ink is printed), that is, more than 70% of the dark colors easily diffuse into Bacheng and Jiucheng. Even 10% (nothing is known as a dot in printing). On the other hand, less than 30% of the light-colored parts tend to fade or turn white. In addition, there are cases where the dots are lost and the tone is lost in the printing process. From this high and low network, there will be a phenomenon of two heads, and the two cannot be balanced. For this reason, the contrast of black and white photography manuscripts must be moderate, and it must be ensured that there are no large blocks in the shadow tone and there are no large blocks in the high-profile spot. We can use photographs with rich layers and low contrast as the draft.
t. Secondary manuscripts. The second manuscript is a manuscript copied from paintings, prints, etc. It should have a smooth picture, no reflection points, and other serious defects. The "reflection point" is caused by the discomfort of the light angle in the remake. The remake of the quadratic manuscript has a loss at both high and low levels, and recaptures a low profile in order to keep a high profile. The two cannot be taken into consideration. In this regard, all manuscripts based on high school tune should be guaranteed at the time of remake, and the manuscripts based on medium tune should ensure that the tune of the tune is high. The more reprints and copying times of a printed matter, the more the loss of the original document layer, so the printed manuscript with high color saturation and a clear picture should be used to remake the second manuscript. In addition, printed manuscripts should not be enlarged after remake.
3 Conclusion Packaging and printing design is a comprehensive, multi-element system engineering. Here, due to the limited space, the problem of the combination of a package printing manuscript design and a plate-making printing is explained only from the point of view of the requirement of the letterpress and offset printing technology for the design of package printing manuscripts.