Printing Process 4: Printing

Printing Process 4: Printing

Due to different printing principles, printing can be divided into four main types: gravure printing, relief printing, and screen printing (stencil printing). Different printing types have certain differences in color separation and film output.

1. The printing plate of offset printing is flat, and this printing method uses a rubber blanket to transfer the graphics and text on the plate to the substrate, commonly known as offset printing.

The role of rubber blanket (rubber) in offset printing is crucial. It is soft and has strong toughness, which can effectively compensate for the unevenness of the substrate surface and facilitate the full transfer of ink. Due to the water repellency of rubber, it can reduce the transfer of water from the printing plate to the substrate, ensuring the adsorption of ink on the printing surface.

Offset printing has various advantages such as fast printing speed, relatively stable printing quality, and short entire printing cycle. Today, books, magazines, and a large amount of commercial printing in our daily lives are all using offset printing. Offset printing is the most popular and economical printing technology, and it is also commonly understood as a printing method.

2. The printing surface of relief printing is protruding, rather than the embossed part being concave, hence it is called relief printing. Relief printing includes two types: movable type and flexible type. Letterpress printing is now a printing technology that is no longer in use. It was developed from early clay movable type, woodcut movable type, and lead cast movable type printing techniques. In modern times, lead typesetting has become the main applied printing technology. At the same time, this printing method is directly printed on paper by the printing plate, so it belongs to a type of direct printing.

Generally, the movable type printing plate is flat, but sometimes it is necessary to copy the flat printing plate into a curved lead plate and install it on a rotary embossing machine for printing large quantities of publications (such as newspapers). In addition to printing images and text, adding some accessories can also create some special effects, such as text patterns on concave and convex printing surfaces, cutting and printing pinhole lines for tearing paper, and adding automatically rotating numerical numbers.

Flexographic printing is similar to letterpress printing, but the difference is that the printing plate is a synthetic resin plate, similar to the rubber used for stamping, commonly known as a flexible sheet. It is cured with ultraviolet light and printed with water-based ink.

3. gravure printing is also a type of printing method. Its printing plate is different from a relief plate and a flat plate, with the graphic and textual parts of the plate being lower than the blank parts, which is exactly the opposite of a relief plate. Gravure printing is the main printing method for packaging printing, plastic film, composite paper, and white cardboard.

4. Screen printing uses a screen made of silk, and with the pressure applied by a rubber scraper, ink is leaked onto the substrate. As introduced in the previous chapter, compared with the three major printing methods of convex flat and concave, screen printing can choose to print on a much wider range of materials than other printing methods. Therefore, screen printing has a wider range of applications and more advantages.

Screen printing is the printing method with the smallest printing pressure. Due to its soft, bendable, and elastic layout, it is not limited by the size and shape of the substrate. It can print on substrates of different shapes and on uneven surfaces. Screen printing has thick ink and strong adhesion. The printing thickness can reach up to 100 μ m, and the ink force is particularly strong, like the superposition of ink, resulting in a strong sense of three-dimensional printing of graphics and text, which is incomparable to other printing methods (the ink layer thickness can also be controlled). Suitable for various types of inks, it has strong adaptability and can adjust any type of coating for printing, such as oil-based, water-based, synthetic resin based, powder based, etc. Various inks can be used as long as they can penetrate the mesh fineness of the screen.

Printing Process 4: Printing