Printing Techniques

Printing T echniques involve several different ways in which printing may be accomplished, such as lithography , letterpress, flexography , gravure, and screen printing. All of these printing techniques use simple mechanisms for rapidly applying colorants to substrates such as paper or plastic to form multiple reproductions of original images for mass distribution. Basically , there are two printing techniques:

Letter Press

Letter Press or Block Printing, a hand process in which the raised portions of a design, cut on a wood, metal, or linoleum block, and iron typefaces are coated with ink or dye and transferred by pressure to paper, cloth, or other material. The process may be used to produce an art print or to pattern textiles.

Offset Printing

Offset printing is a widely used printing technique where the inked image is transferred (or “offset”) from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a film of water, keeping the non-printing areas ink-free.

Multiple colors can be printed in one pass through the press. Spot color printing uses custom mixed inks to reproduce specific colors and is widely used in package printing, where large areas of uniform color are common. Process color printing uses four transparent inks (blue-green), (red), , and black (cmyk) printed cyan magenta yellow
one on top of another in varying amounts. The different colours are achieved using four lithographic plates that carried each of the colour of cyan, magenta, yellow and black.

Most modern printing presses transfer ink from a cylindrical printing surface to moving sheets or rolls of substrate using one plate at a time or a combination of two, four or more plates on one machine. Presses that print on rolls, or webs, can achieve speeds of 600-900 m (2000-3000 ft) per minute. Presses that print on sheets are generally slower than web presses but can print on thicker substrates, such as bristol board and sheet metal