How to distinguish between spot color and four-color printing?

Spot color refers to the printing process that uses inks other than C, M, Y, and K inks or mixes a single ink with C, M, Y, and K inks to reproduce the color. Package printing often uses spot colors to print large areas of background color. So what kind of products will use spot colors?

The cover of packaging products or books and periodicals is often composed of uniform blocks of different colors or regular gradient colors and text. These blocks and text can be made by using four primary color inks after color separation. You can also mix spot color inks for printing, and then only print one spot color ink on the same block. In the case of comprehensively considering improving printing quality and saving the number of overprints, sometimes you have to choose spot color ink for printing.

Four colors (usually composed of dots) are the printing process of using C, M, Y, K inks (cyan, magenta, yellow, black) to copy the various colors of the color original. What products use four-color printing? Generally speaking, photos taken in the form of color photography that reflect the colorful color changes in nature, human expressions, painters' works of art, or other pictures containing many different colors. For technological requirements or economic considerations, the pictures must be scanned by an electronic color separation machine or a color desktop system. Then the four-color printing process is used to copy them.

What is the difference in the visual effect of the color blocks produced by the collision of spot colors and four-color inks?

The color of the ink prepared by spot color printing is obtained according to the principle of subtractive color mixing of colorants. Its color brightness is low and the saturation is high. The solid base with uniform ink color is printed with spot color. When the amount of ink is appropriately increased, the change of the thickness of the ink layer will reduce the sensitivity to color changes. Therefore, it is easier to obtain a printing effect with uniform and thick ink color.