Printing uses a variety of techniques to create a visual impact. It is a form of communication, employed for purposes as diverse as education, information, entertainment, promotion and art.

Nature of Work

Working in this industry requires professionals at all levels to be fully conversant with current printing technologies. At a technical level, the knowledge and handling of machines and equipment is essential. 

On the managerial side, personnel must be aware of factors such as the efficient and appropriate use of materials and techniques; speed; cost; quality; end use and appearance. Besides print production jobs, technicians and technologists work on the research and development of new
printed materials, machinery, paper and inks while designers/printmakers are involved in devising new faces and styles of type.

PRINTING PROCESSES

Printing is a form of duplication. There are various techniques by which this can be done-such as:

LETTER PRESS

Technically known, as relief printing is the most commonly used method. It employs the use of blocks, types, stereos or electrodes on which the images to be printed are carved in relief-that is, raised above the surface. When inked and brought in front of the material to be printed, the images are transferred onto it, producing a print. This process produces bright, sharp images. 

Its main advantage is that last-minute changes are possible in the text, even as the matter is going to press. It also requires the shortest time between the receipt of a manuscript and supply of printed copies. 

Its drawbacks are high material costs, and the necessity for good quality art paper for half tone illustrations. The letterpress method is used mainly for the printing of stationery, as well as newspapers, books and journals with limited print orders.

LITHO OFFSET

Is based on the principle that oil and water do not mix. Its technical name is Plano graphic printing. The metal plates used in this process are chemically treated to make the surface areas around the images to be printed water absorbent. When the plate is immersed in water, and an oil based ink applied, it coats only the print areas. 

This is also called the indirect method, as impressions are transferred onto a `blanket', before being reproduced on paper. Offset printing is cost effective for large print orders, and for those with a great many illustrations. It is best suited for reprint jobs, where recomposing and block making are not required. Any corrections or changes in the material would mean making up a whole new plate. 

Offset printing uses high-speed machines and produces good results even on inexpensive paper. However, impressions are not as sharp as the letterpress method, and it is not a good method for small print orders.

GILTWARE

Also called the intaglio process, works almost in, reverse of the letterpress method. Images to be printed are etched onto the surface of copper `forms'. Ink fills the grooves in the forms, which are then wiped clean before being placed in contact with the paper on which the impression is to be
made. 

This process is ideal for full color printing of very large orders. The gravure method can achieve a rich gradation of tones even on low-grade paper. However, it is more expensive than any of the other methods.

SILK SCREEN

Or serigraphy is basically a form of stencil printing. It is the only method that allows impressions to be made on irregular and cylindrical objects as well as the usual plane surfaces. This process is widely used for limited orders of stationery, invitation cards, posters and other jobs where liberal deposits of color are required. Its recent mechanization has made silk screening faster and less
expensive than it was earlier.

FLEXOGRAPHY

Also called the aniline process is very much like the letterpress method, but makes use of rubber and plastic stereos instead of metal. It is a low cost, high-speed process, and therefore used for large runs of industrial jobs like the printing of wallpaper, flexible plastic sheets and other similar packaging materials.

XEROGRAPHY

Is an inkless process that uses static electricity rather than pressure to transfer images from the plate onto paper. By this method, dark areas are highly charged, and a cloud of fine powder is released over the electrified plate. 

When placed in contact with a sheet of heated paper, the resins in the powder melt, and fix the impressions permanently onto the paper. Xerography is used extensively for making quick copies of records, correspondence, drawing and forms.