Screen printing 2001-2

Offset monochromator prints the first color and the second color for an interval. During this time, the binder in the ink gradually penetrates the sheet, and the ink surface gradually oxidizes the conjunctiva. When the second color is printed, the ink is printed on the conjuncted ink layer, which is called wet-press drying. Multi-color printing machine at the time of printing each color version of the ink superimposed in less than a few seconds together, the interval between the colors is very short, the latter printing color is not printed on the oxidized conjunctiva layer of ink This is the so-called Wet pressing wet. Multi-color machine in the "wet pressure wet" process, the white paper most easily accept the first set of ink. Black is the most obvious, followed by cyan and magenta. It is called the three strong colors. The human vision is the slowest to reflect on yellow, so it is placed last. The ink of the first color group should be thicker, and the concentration of the various color inks afterwards is gradually reduced. The black color is printed on the first color to facilitate overprinting accurately. This is why multicolor machines are mainly based on black, cyan, magenta, and yellow. (Generally, 4-color ink viscosity relationship: T black ≥ T blue = T red> T yellow. T represents ink stickiness value) Overprinting of multi-color machine ink is performed under the condition of “wet to wet”, and the stickiness and overprinting of ink are In terms of the relationship, the tack value of the back color ink should not be too much larger than the previous color ink, otherwise the previous color ink that has just been printed on will be stuck down and transferred by the rubber roller to the printing plate, which not only causes the “color mixing” of the ink. In addition, the ink is not printed, and the ink on the print is very light and not spirited. Found that this situation can take to adjust the viscosity of the four-color ink or change the order of the ink to remedy the method. (Adjust viscosity of the ink by adding a viscosity-reducing agent such as mineral oil or adding some tackifiers such as zero varnish.) Arrangement of the color sequence method should follow the principle of highlighting the main color to prevent the main color from being covered to determine the color sequence. . In general, the color area is based on the screen area and the dominant color. Therefore, after accepting product printing orders, we must analyze the focus of a certain color of the sample draft screen, change the color sequence to meet the original, to fully express the original, and better reproduce the tone and color. The portrait-oriented pictures (warm tones) of the general portrait calendar are dominated by black, blue, red, and yellow. In general, large-scale landscape-dominated pictures (cold) are mainly black, red, blue, and yellow. The large-area four-color stacked spot color should be dominated by the dominant color, which includes a large area of ​​black, and does not rule out the possibility of the final printing sequence. For some of the different shades of the main color version in the case of printing and proofing the gap between the more difficult circumstances can be used to fold the printed version of the method or multiple exposure printing PS version method. In short to restore the main color. Be bold and science. It is necessary to fully understand that plate-making proofing is round-pressing and printing is round-pressing. The fact that dot gain value printing is greater than proofing. In summary, the arrangement of multi-color machine color sequence has a close relationship with the quality of printing quality. How to arrange the color sequence scientifically and rationally is still a subject of our research in process technology. (Zhou Yifeng)