Know packaging Offset (E)

Therefore, the color of the dots is composed of two components; the side-by-side dots selectively absorb the incident white light respectively; after the absorption, the residual color is not additively mixed. Since the color added by the additive method contains a white component, the color of the new color exhibiting parallel coloration is relatively high, but the chroma is low, and the new color can be perceived only when the human eye cannot distinguish the presence of dots. If you look in a magnifying glass, you can only see the small dots of different colors, but you can't see the color of their synthesis.
32. What is four-color printing?
The four-color printing process generally refers to a printing process that uses a yellow, magenta, and blue primary ink and black ink to reproduce the color of a color document.
33. What is spot color printing?
Spot color printing refers to a printing process that uses a color ink other than the four colors of yellow, magenta, cyan, and black inks to reproduce the color of a document. In the packaging printing, spot color printing is often used to print a large area of ​​background color.
34. What product must use four-color printing process?
Photographs taken in color photography that reflect the variety of nature's colorful color changes, painter's color art wounds, or other images containing many different colors must be passed either for process reasons or for economic considerations. The electronic color separation machine or the color sampling system scans the color separation and then uses a four-color printing process to complete the copying.
35. What kind of product will use spot color printing?
Packaging products or books and periodicals are often composed of uniform blocks of different colors or regular gradient patches and texts. These blocks and text can be color-coded and printed using four-color inks. Spot inks can also be dispensed. Then only one spot color ink is printed on the same color patch. In consideration of improving printing quality and saving the number of overprints, spot color printing is sometimes used.
36. What is the difference in the visual effect of color between a spot color block and a four color block?
The inks prepared by spot color printing are obtained according to the principle of mixing by the subtractive colorants of pigments. The color brightness is low and the saturation is high. The uniform color blocks of ink are usually printed in the field and the ink volume is appropriately increased. When the layout of the ink layer is large, the sensitivity of the change in the thickness of the ink layer to the color change will be reduced, so it is easier to obtain a uniform and thick printing effect of the ink.
The use of four-color printing process overprint color blocks, due to the composition of the color of the various colors are mostly composed of a certain percentage of dots, when printing dots, the ink layer thickness must be strictly controlled, easy to change due to the ink layer thickness and printing Changes in process conditions cause changes in color intensity, changes in dot gain, and color changes. Furthermore, since any color change that composes the color block will cause the color of the color block to change, and the chance of occurrence of uneven ink will multiply, the color blocks overprinted by the four-color printing process are not easy to obtain ink color. Uniform effect. If the color of the color block cannot be overprinted with a multi-color machine at one time, color shift may easily occur due to the uneasy control of the color of the semi-finished product. In addition, the combined effects of subtractive color absorption and additive blending of dots obtained by four-color printing are high in lightness and low in saturation. For light-colored blocks, a four-color printing process is used. Due to the low coverage of the ink by the ink, the lack of solid ink is bland. In the ink, the coverage of the paper is low, and the bland ink lacks a solid feeling. Due to the chromaticity of the dots, it is inevitable that people will feel the presence of patterns.
37. From the perspective of improving product quality, what kind of product is suitable for spot color printing?
In the printing of a large area of ​​light-colored uniform color blocks, usually used in the original ink to add a diluting agent to match the spot color ink, and then field printing, so that the ink layer is thicker, easier to get uniform color, thick effect. If you use a four-color printing process, you must use a low number of flat screen dots. However, low-level flat screen outlets are liable to cause small unevenness in ink at the individual sites due to slight sand particles or slightly poor suction during printing, and the ink is uneven when printed; Stacking on blankets, low paper smoothness, etc. cause poor transfer of ink on small screens, resulting in lighter inks and uneven ink.
For dark, large-area color patches, a four-color printing process may require the superposition of several colors of high-number dots, and the ink layer is too thick to be easily stained on the back. With spot color printing, only a single color printing process is required. The color is not easy to appear dirty on the back. With the four-color printing process, some parts of the graphic text may be synthesized by several colors; and using the spot color printing technology, the corresponding parts only print one color, which avoids the possibility of overprinting errors.
38. From the perspective of economic efficiency, what kind of product is suitable for printing with spot colors?
From the economical point of view, it is mainly to see if the spot color printing process can save the number of overprints. Because reducing the number of printing can not only save printing costs, but also can save the cost of prepress production. (Finish)