The reason that affects offset color

1, the relationship between the absorption of the paper and the ink layer

Due to the great difference in absorption of various inks, the absorptivity of coated paper is small, and the absorptivity of letterpress paper and offset paper is large. The paper with high absorbency often causes the imprinted ink layer to solidify, resulting in large losses in the drying process. . Since ink binders penetrate into the paper fibers, the gloss of the Shanghai printing plant's footprint will be affected, and the surface will become rough and the color will change. When printing fine products, be careful to use paper that cannot absorb too much. In addition, when printing offset printing, the dry, wet ink color of the blotted ink color is different. Offset ink color is just printed out of the wet state of the ink, the color is darker. After the offset ink blot is dry, it will be lighter. Therefore, when distinguishing colors, it is necessary to fully estimate its influence and increase the thickness of the ink layer within the allowable range in order to compensate for possible loss of color density. When using poor quality, loose structure, rough surface paper, in order to avoid ink color error may occur when the sample can be printed for a certain period of time, to be dry, then determine the degree of color.

2. When comparing color samples, what factors will affect the color

When offset printing is compared with the printing ink color sample and printing ink color size and hue is exactly the same, the environmental color has a greater impact, as well as light (sunlight) brightness and darkness and color cast, and each person's color blindness physiological phenomena have a certain impact. When looking and signing, the sample should be framed and framed to reduce the influence of ambient color. In addition, the Y color is judged by its opposite color, blue-violet (B) glass, Y size ink size and dot gain, RC, CT (green)  m, and the glass plate is judged by its opposite color and color filter method. Use a color densitometer to measure dot changes. Under the unified standard light source, look at the color of ink and determine the color when comparing colors: red and green, white, and black; when you are tired, look for color errors. You should first look at the green trees and adjust the visual fatigue.

3, the whiteness of the paper

The ideal whiteness of printing is 100% total reflection, especially the identification of color. It is necessary to realize the importance of whiteness of paper, especially the paper which is one of the main factors for distinguishing color, and the blank paper bearing the color of the color. Whiteness plays a decisive role in the appearance of hue, brightness and saturation. Shanghai printing plants usually require a reflectance of greater than 85% for coated paper for printing fine products. The paper used for proofing during offset printing should be the same as the whiteness of printed paper for formal printing, otherwise it is difficult to accurately evaluate the ink color effect. It must first be stipulated that paper with sufficient whiteness be used. In the printing process of the same batch of products, the used paper should have the same color, otherwise, it is impossible to keep the ink of the product consistent.

4, the impact of environmental color

Ambient colors also have a significant effect on correct color discrimination. Similarly, when observing and analyzing colors, the process of seeing must avoid the illusion of color. A color in a specific environment, the human eye vision due to psychological effects easily lead to illusion, need to know it, so as to avoid the color of the environment caused by the color error. The same is a kind of green, placed in a yellow environment, with a greenish-white contrast to a bluish; while green is placed in a colored environment, it is yellowish. The same is the gray background, reddish in the green environment. The black 50% dot gray block is placed in a black solid and 10% dot environment, and the brightness of the two is noticeably different. These are the results of discoloration caused by the illusion of color. From this reasoning, when distinguishing the color of a certain color body, it is necessary to avoid the influence of the environmental color. When comparing the colors of a plurality of sets of color printing products, it is necessary to pay attention to covering other colors. At the same time, in the case of proofs and printing-like solid patches, it can be grouped together, and the interference of ambient colors must be eliminated, so as to avoid the color deviation due to the visual effect.