Print color reproduction conditions

In order to achieve a bright color reproduction, the print must satisfy two conditions based on the hue of the hue: first, the color has a higher saturation, ie, the purity is better. The second color has a higher lightness. In addition, we must pay attention to the following questions on this basis:

1 sheet

Substrate is the basis for the bright colors of the printed matter. According to the principles of print coloration, the color of the surface of the substrate printed on the Internet site is not printed except that each color dot forms the visual color of the human through additive color mixing. In fact, this space is also involved in the mix. Therefore, if the whiteness of the substrate is high, the brightness of the color can be increased. On the contrary, the gray substrate is like adding a small amount of black to each color ink, thus showing a dark turbid color. In addition, the absorbency of the substrate will affect the saturation of the color. Absorbent substrates, blots can not form a sufficiently full ink layer on the surface of the blot, excessive penetration of the link material into the substrate to make the blot dry. Paper with large pores will cause some pigments to infiltrate into the paper together with the binder, thus reducing the color saturation and affecting the vividness of the color.

2 ink

The color characteristics of the three primary inks directly affect the degree of vividness of the prints. Different types of three primary inks have different color shifts, gray scales, and efficiencies. Therefore, the vividness of ink colors is also different. Therefore, when printing fine products, Choose the same type of bright ink as the manufacturer. In addition, in the printing process, try not to add too much auxiliary agent in the original ink, so that the ink emulsification or saturation decreases. When color changing, if the previous color ink is not washed, the color deviation of the ink of the latter color will increase and the gray scale will increase, which will affect the color reproduction of the print.

3 Plate material

Most of the plates used for water offset printing are PS plates. PS version is based on the polymer photo-sensitive layer as a graphic basis, dried printed plate graphics slightly higher than the blank part. The hydrophilic part is a film of aluminum oxide. Waterless offset printing uses a unique pre-coated offset printing plate. The blank part is a kind of silica gel that repels ink. The image part is a layer of slightly concave polymer, and the surface of the plate is resistant to oxidation. PS printing quality directly affects the quality of prints.

4 ink thickness

In the actual printing process, the ink layer thickness affects the color reproduction. The thickness of the ink layer is thin, and the displayed image is dark and dull; the thickness of the ink layer is thicker, the dot enlargement value is increased, and the dark tone is easy to be padded. The picture presented is boring and the level is unclear. Therefore, the thickness of the ink layer must be balanced with the tone reproduction. In general, under the premise of quality assurance of the printing plate, the thickness of the ink layer should be adjusted according to the provided proofs. For monochrome machines, pay special attention to the first color of the sample. The thickness of the first ink layer directly affects the color reproduction of the entire screen.

5 overprint rate

The overprint ratio indicates the ratio of the ink amount of the previous color printed in the latter color and the amount of ink directly printed on the paper in the latter color. The ratio is always less than 100%, which means that the amount of ink printed on the previous color in the latter color is definitely less than the amount of ink directly printed on the paper in the latter color.

The size of the overprinting rate affects the saturation of the secondary color. The overprint rate is large, the saturation of the color is large, and the color is more vivid. For monochromatic machines, the superimposition rate is generally high, and for multicolor machines, not only is the superimposition rate low, but it also causes the phenomenon of color mixing before and after color.

6 network expansion

In the offset printing process, dot enlargement is unavoidable, but the size of dot gain can be controlled. If the dot gains are small, the colors are relatively bright. On the contrary, if the dots are enlarged, the larger ones will have to reduce the thickness of the ink layer to ensure the correctness of the hue. This makes the dark tone and the solid part not thick, and the color saturation weakens. This affects the vivid color of the entire screen.