What is offset printing

Offset printing

The credit for the discovery of offset printing goes back to the Alkanian writer Aloi Seinfelder, and that was in the year 1798 AD. Seinfelder was transcribing his work on stone with a pen made of a greasy substance. He was putting water on the unpainted parts of the stone before the printing process, and he noticed that the ink It remains coherent in its place, and before the ink dries, he would place his paper on the drawings and writings on the stone and press it firmly in all its aspects, so he noticed that the drawings moved to the paper, and this method is still used until now, especially by artists and sculptors. It comes out in this way, original, and there are only a few numbers, and many people are interested in buying it.

This type of printing was considered commercial because of the high price of the graphics, and with the development, the stone surfaces were replaced with sheets of metal foil, on which the drawings were placed through photographic techniques, by dropping the inked graphics on a rubber cover located on the surface of the cylinder, and the cylinder In turn, it is printed on paper, and offset lithography is the most widely used for printing books, magazines, metal presses, and cardboard on boxes, and its name is traded in flat surface printing, or litho.

Offset printing method

Offset printing plates are prepared through a process called photolithography from the printing surface and the final design, and negative copies of them are placed on a metal plate that is sensitive to light in a process called vacuum, and is exposed to strong lighting through lamps, and the graphics drawn are affected as they are the most exposed to light. This increases its hardness, and it is covered with lacquer, which increases its hardness. Shellac is a coating used to cover metals, and the remainder of the coating is removed by water, and this will lead to the emergence of voids in areas of the drawings, so the glue was used to fill these voids, and thus the proportion of lacquered parts increases with its inclination for printing.

The system of independent units is a system for most offset presses, some of them print one color such as black or blue or any other color independently, and some of them print two or more colors, and there are some complete offset presses that print both sides of the paper at one time, using ready-cut paper systems That is, it relies on printing rubber cylinders through mutual pressure, and then each cylinder transfers the graphics it contains to both sides of the paper.

Characteristics of offset printing

• It has high accuracy.
• It can be printed on stone, metal, wood, canvas, and leather.
• Its cost is high when the quantity of printing is small, and its cost is low when the quantity is high.
• It is printed on water and ink.
• It takes a lot of time to print it.