Offset Printing

How the offset printing process works

Printing plates are produced from the artwork (a computer-prepared file). The plates are mounted on a cylindrical roller in the printing press, after which they pick up ink and «transfer» it to a «rubber blanket» — which, in turn, applies the ink to the required surface (paper, cardboard).

Offset presses vary: different paper and cardboard; the number of inks per single pass of a sheet, the type of drying unit, the type of dampening: «alcohol» — «water» (which directly affects the brightness of the applied inks), and many other auxiliary processes and devices.
Products (paper)

The products manufactured (although they are a semi-finished item) are limited by the material: the density and texture of the paper/cardboard, and the format.

Offset printing is used to create a wide variety of products: books, magazines, posters, leaflets, business cards, labels, etc.
Features

There are certain technical requirements for the artwork (individual in each case).

An offset press prints at high speed. The production process involves setting up the press for each individual print run, which leads to some paper/cardboard being used beyond the run (this is «make-ready», as well as rejects during printing). It is worth noting the need to produce overrun copies for subsequent post-press processes.

Printing is done in formats from A3 to B0.

In most cases, printing is done on a four-colour press. There are presses with a different number of inks. The colour capacity is limited not only by the capabilities of the equipment, but also by the density of the paper/cardboard.

On very thin materials, full colour (4-colour printing) is not possible; in this case rotary printing is used (printing from a roll — newspaper printing).

To produce items on very dense materials, the «cashing» (mounting) method is used. Printing is done on thin materials, which are then glued onto «thick» cardboard.
See also:

Screen printing. (silk screen or silkscreen printing)
Digital printing
Large-format printing