What are the types of printing?

Generally, it can be divided into four categories: relief printing, gravure printing, lithography and stencil printing. The graphic part of the printing plate used in relief printing is convex, including block printing, movable type printing, lead printing, copper-zinc printing, photosensitive resin printing and flexographic printing. Flexographic printing has developed greatly since 1980s, and its printing machine structure and printing substrate are different from general relief printing, so some countries regard flexographic printing as an independent printing category. The graphic part of gravure printing plate is concave, which can be divided into engraving gravure printing, photographic gravure printing and electronic engraving gravure printing. The graphic and non-graphic parts of lithographic printing plate are basically in the same plane, which usually refers to offset printing, but in fact lithography (which has been basically eliminated) and offset printing? Lithographic printing (preserved as a unique process) also belongs to the category of lithography. Stencil printing is mainly screen printing, that is, a printing plate made of screen, in which the graphic part can pass through ink, but the graphic part cannot pass through ink. Copying mimeograph is also a kind of stencil printing.

According to the printing procedure, the above four printing methods are different from direct printing and indirect printing. Offset printing is indirect printing, and all other printing methods (including lithography in lithography) are direct printing. The graphics and text of the direct printing plate are reverse images, and the graphics and text of the indirect printing plate are positive images.

Although the above printing method is different from the printing process, when printing, the paper (or other substrate) contacts the printing plate and exerts certain pressure, which belongs to contact embossing. With the development of computer technology and equipment, laser printing and inkjet printing have appeared. These new methods are called non-contact or pressureless printing because they have no impression in the printing process.