How to overprint for color book printing?
For example, when the surface of the printing paper is smooth and the ink absorption is poor, the base color printing ink layer should be thinner to avoid smearing during overprinting. In addition, the background color should be printed thinly, the multi-color printing effect is good, and it is conducive to the drying of the over-printed ink layer.
For offset paper products with rough surface and large ink absorption, the ink volume of the background color should be appropriately thickened, so as to lay a solid foundation for obtaining a thick gloss for a flat garment. When printing a multi-color overprinting plate, the ink layer is thinner than the base color, and the blended ink color is slightly lighter than the original hue, because the base color is basically close to the original color, and the overprint does not diminish, and the printed product will be darker than the original.
In order to ensure the normal color registration and prevent the undesirable effect of overprinting due to the difficulty of drying the ink, when printing the background color and the multi-color plate, the China printing company should respectively add an appropriate amount of dry oil according to the amount of ink absorption on the plate surface to ensure printing. quality. Generally, the amount of white dry oil is 2%~5% for resin ink, 3%~10% for oily ink; the amount of red dry oil is about 2%. Because dry oil has an effect on the ink color, white dry oil is mostly used in light-colored inks, while red dry oil is mostly used in red and dark inks to avoid deviations in ink hue.
If you overprint on the red or yellow background color and print gold on the background color, in addition to the blank part, you can make a solid plate and print transparent yellow or bright diluent to increase the gloss of the solid plate. In order to ensure the quality of overprinting and prevent overprinting, in addition to overprinting black characters on the gold plate and the background color of the white ink thinner, generally you can print the black characters first and then print the large area background color layout, which can avoid the background color on the printed product. The ink layer is rubbed and scratched on the machine. In addition, in order to ensure the accuracy of overprinting, after the background color pin position (that is, the rules) is determined, when the overprinting position of the overprinting plate is adjusted, the position of the printing plate can only be adjusted, and the position of the front and side rules can not be adjusted to avoid paper. There is an invisible "water wave line"-like unevenness on the edge, which affects the stability and accuracy of overprinting.
For the pattern of Yin and Yang overprinting, one of the plates can be appropriately enlarged to overcome the inaccurate overprinting caused by the machine precision defect and the change of environmental temperature and humidity caused by the expansion and contraction of the printed matter, which causes the page to leak and affect the product quality.
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