一. Classification by printing plate type
According to the classification of printing plates, common printing methods can be divided into four categories: letterpress printing, gravure printing, offset printing, and stencil printing:
1. Letterpress printing: Printing using letterpress plates (printing plates with raised graphics and text), referred to as letterpress printing. The printing principle is similar to that of seals. Early woodblock printing, movable type printing and later lead type printing are all letterpress printing;
2. Gravure printing: The ink contained in the pits of the gravure is directly pressed onto the substrate, often used for printing banknotes, stamps, and other securities;
3. Lithography: It is an indirect printing method. The graphic part and the blank part of the printing plate are almost on the same plane. It uses the principle of oil and water immiscibility to print;
4. Hole printing: Also called screen printing, it is a printing method that uses silk screen as the plate material. This method can be used to make prints, and can also be used for packaging and printing of daily necessities and industrial supplies.
二. Classification according to printing principles
According to the principle of producing printed matter, it can be divided into two categories: physical printing and chemical printing:
1. Physical printing: The printing ink in the printed part is completely accumulated and carried, and the non-printed part is concave or convex. The height is different from the printed part and cannot be stained with the printing ink. It is left blank, so the printing Part of the printing ink is transferred to the printed material, which is a physical and mechanical effect. Generally, relief printing, gravure printing, stencil printing, dry lithography, etc. are all physical printing;
2. Chemical printing: During the printing process, the non-printed part must be continuously replenished with a water-absorbing and ink-repellent film, which is chemical printing. Offset printing falls into this category. In offset printing, glue substances must be added to the water tank solution to supply a mucus layer of carboxyl groups continuously to keep the non-printing surface of the printing plate from being contaminated by grease.
三. Divide by printing color number
According to the number of printing colors, the following distinctions can be made:
1. Monochrome printing: not limited to black, any color displayed in one color is monochrome printing;
2. Multi-color printing: Multi-color printing is divided into three categories: additive color method, color registration method, and double color method;
3. Color printing: that is, multi-color printing. All color prints, except for a very small number of color enhancement methods and color registration methods, are all printed by the compound color method;
4. Four-color printing: Generally refers to the printing process of using three primary colors of red, green, blue, and black color materials to copy color originals. According to subtractive color absorption and additive color mixing, the color block has higher brightness and lower saturation.
四. Classification by printing purpose
Classification according to the use of printed matter, such as book printing, news printing, advertising printing, packaging printing and special printing, etc.:
1. Book printing: Letterpress printing was used in the past, but later it was gradually switched to offset printing;
2. News printing: In the past, letterpress rotary machines were used for printing because of their high speed and large printing volume. Nowadays, in order to meet the needs of color, offset printing or gravure printing is used instead;
3. Advertising printing: including color pictures, pictorials, posters, etc., most of them use offset printing, but letterpress, gravure, or hole printing is used;
4. Packaging printing: Candies, snacks, packaging cartons decorative wallpapers, etc., are mostly printed with gravure printing;
5. Special printing: such as bottles and cans, hot stamping, embossing, hoses, labels, etc., mainly with special processes or special materials.