Basics of the Printing Process

Direct vs. indirect printing

The five major printing processes are distinguished by the tactic of image transfer and by the overall sort of image carrier employed. Depending upon the method, the printed image is transferred to the substrate either directly or indirectly. In direct printing the image is transferred directly from the image carrier to the substrate, samples of direct printing are gravure, flexography, screen printing and letterpress informasi percetakan processes.

In indirect, or offset, printing, the image is first transferred from the image carrier to the blanket cylinder then to the substrate. Lithography, currently the dominant printing technology, is an indirect (offset) process.

Image carriers

Image carriers (or plates) are generally be classified as relief, paleographic, intaglio, or screen.

• In letterpress, the image or printing area is raised above the non-image areas. Letterpress and flexography are letterpress processes.

• In paleography, the image and nominate areas are on an equivalent plane. The image and nominate areas are defined by differing physiochemical properties. Lithography may be a paleographic process.

• In the intaglio process, the nonprinting area is at a standard surface level with the substrate while the printing area, consisting of minute etched or engraved wells of differing depth and/or size, is recessed. Gravure is an intaglio process.

• In the screen process (also referred to as porous printing), the image is transferred to the substrate by pushing ink through a porous mesh which carries the pictorial or typographic image.

Steps of the printing 

Each printing is split into prepress, press, and post press steps.

• Prepress operations encompass steps during which the thought for a printed image is converted into a picture carrier like a plate, cylinder, or screen. Prepress operations include composition and typesetting, graphic arts photography, image assembly, and image carrier preparation.

• Press refers to actual printing operations.

• Post press primarily involves the assembly of printed materials and consists of binding and finishing operations.

Chemical use

Each process uses a spread of chemicals, counting on the operation involved.

• Prepress operations typically involve photo processing chemicals and solutions.
• Inks and cleaning solvents are the main sorts of chemicals used during press operations.
• Depending on the finishing work required, post press operations can use large amounts of adhesives. This is often very true where the assembly of books and directories is involved.

Of all the chemicals utilized in a typical printing plant, inks and organic cleaning solvents are the categories utilized in the most important quantities. Many of the chemicals utilized in the printing industry are potential hazards to human health and therefore the environment.

Prepress Operations

Prepress consists of these operations required to convert the first idea, like a photograph or sketch, for a printed image into a printing plate or other image carrier.

Prepress steps include:

• Composition and typesetting,
• graphic arts photography,
• image assembly,
• color separation, and
• Image carrier preparation.

With the exception of image carrier preparation, the prepress process is analogous for the five major printing processes. Placeless process does most of the prepress steps employing a computer.