Commercial Printing

Written by Christopher Ransom
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Commercial printing is business managed printing above and beyond the desktop printer, typewriter, or ink that comes from your ballpoint pen. Individuals and businesses hire commercial printing companies to create business cards, brochures, advertisements, posters, magazines, catalogs, and books. The commercial printing industry uses a specific set of skills, technology, and materials that most of us are not familiar with. Understanding the language, if not all of the technology, used in commercial printing might help you communicate better with your printer and help you decide where to print your book.

Two common terms emerge: The image carrier and the substrate. The image carrier refers to the equipment that delivers the image, represented in ink or toner, to the substrate. Substrate refers to the paper, cardboard, vellum or other material that the image will be printed on. In the old days, you could say the image carrier was the paintbrush and the substrate was the canvas.

Types of Printing Processes Used in Commercial Printing
The letterpress is the oldest printing process. Think metal typewriter keys and, earlier, wooden blocks that acted as stamps to print paper with ink or paint. The impracticality of the letterpress is that physical plates, such as a typewriter key, had to be created to represent the image. Not very useful if your company logo is something other than the keys found on a typewriter. Flexography uses flexible letterpresses to accomplish basically the same thing on a greater variety of surfaces (a roll of tape, for instance). Serigrapic printing or silk screening is a printing process that uses a squeegee to force ink through a screen while the non-image area is kept ink-free. This process is still used for printing on cloth and porous materials such as t-shirts, ceramics, mouse pads and the like.

For book printing, the most common commercial printing process is lithography.
Lithography uses an offset press for indirect printing, meaning the image and substrate do not come into contact. Here, the book printer uses digital technology (a computer) to scan or create the image onto a virtual image plate. Once manipulated and set, the image is transferred to two different physical plate cylinders capable of cleaning or resetting the image as needed. Water is applied to the non-image areas and ink is applied to the image areas. Using a series of cylinders to transfer the image from virtual plate to the physical image plates and eventually the substrate (paper), the image is brought to life. This printing process is fast and inexpensive, allowing commercial printing companies to store and print many different images, including your book, on demand.


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