Printing is a method of duplication (multiplication) of the master copy. Whether it is a text or picture, printing on paper, plastic or cardboard.
There are several printing techniques one can choose from. Each printing technique is unique and has its advantages and disadvantages. But there was one feature that was common to all of them until recently. They were inherently bundled with a physical value - pressure. Either it was exerted by a lever or a set of cylinders.
This is no longer true with the development of the new technologies. The digital printing does not need the pressure, printing takes place even without a mechanical interface - printing plate.
Printing technique types
They are divided based on the arrangement of the printing and non-printing areas on the printing plate.
When using Letterpress the printing areas rise above the non-printing areas. Thus the ink is applied only at the printing areas that are then transferred to the printed material (e.g. paper).
With using Planography, the printing and non-printing areas are at the same height. The difference between them is in the physico-chemical properties. The printing areas are modified to be ink-receptive; the non-printing areas are modified to be ink-repellent. When the ink is applied the printing plate is pressed to the printed material.
The most often used planography technique is Offset printing. The other techniques are Lithography and Phototypesetting.
When using gravure printing, the printing areas are lower than the non-printing areas. The ink is applied on the entire area of the printing plate and then it is wiped away. This way it is ensured that the ink remains only on the printing areas. These areas are then printed on the material using the pressure.
When using the screen printing the ink is strained through the printing plate. The non-printing areas are prepared so that the ink cannot go through.
The only technique that falls within the screen printing is Silkscreen printing.
The digital printing is the only method that does not use the pressure and the mechanical interface - printing plate that is pressed to the printed material. Printing takes place directly. The files in the computer are transferred directly to the paper. Digital printing is the newest and state-of-the-art printing technique that utilises principles of xerography or ink-jet.
Digital printing in details
Sheet printing and rotary printing
The sheet-fed printing and rotary printing (that is also called web-fed printing) can be recognized in terms of mechanics of the printing machines. Rotary, or web-fed printing utilizes a virtually endless paper roll as the printed material. Only after printing the roll is cut into individual broadsheets. The advantage of this method is the printing speed that is higher than with the sheet-fed printing. This method is nowadays used e.g. for printing the newspapers.
On the other hand, the sheet-fed method uses the individual sheets and each paper is printed separately. The printing speed is lower than with the rotary printing but the sheet-fed printing machine design is simpler.
Want to know more? Click here: offset printing.