What Is Offset Printing?
Offset process printing, sometimes referred to as 4-color process or CYMK printing is the technique of printing with 4 standard colors; CYMK: Cyan, Yellow, Magenta and Black. This industry standard for “full-color” printing allows for near “true-to-life” color printing. The technique or process prints all 4 colors as miniature dots in precise closeness to each other. The size of each dot and its relation to the other dots is what provides the finished look of colors and tones. Most full-color brochures, magazines, newspapers, and yes, CD packaging and CDs are process printed. When process printing is not required, Pantone colors are specified.
Offset printing presses use the same method as four-color process printing on paper, in which the four ink colors (cyan, magenta, yellow, black) are transferred from plates to rollers to the printed surface. This technology was originally developed for printing on DVDs. Because offset printing applies a thin, even layer of ink, it solves the problem of unbalanced weight or “wobble” that sometimes occurs with silkscreening.
Offset printing works because of hydrophobia, oil and water don’t mix. A photographic image in created on a flat metal printing plate that has a grainy surface that holds liquids well. The ‘image area’ on that plate has a coating that is receptive to oil-based printing inks while the uncoated areas tend to accept water and repel ink. Roller systems on an offset press supply measured amounts of ink and water to that plate allowing an image to form on it’s flat surface. Other rollers transfer the image from the metal plate to a cylinder covered with a flat rubber mat called a ‘blanket.’ Finally, paper is delivered past the blanket cylinder and squeezed slightly against it by a third ‘impression’ cylinder. The ink transfers from the blanket to the paper and you have printed!
