So there are monochrome, bicolor and four-color printing.

At present, there are more advanced five-color, six-color and even eight-color printing machines abroad, which add some additional effects on the basis of the original four colors, such as polishing and black ink.

Hexachrome, a printing method developed by Pantone Company in the United States in 1995, uses unique six-color ink. Except for black and blue, all other colors of ink contain fluorescent pigments, which are characterized by very bright colors.

According to Pantone's design, the six inks used are cyan, magenta, yellow, black, orange and green.