| Step A: Plates Are
Made For the Presses After pagination (or page make-up) is completed, the next step is to transfer the images from the computer to an aluminum plate in the plate-making department. Each aluminum plate is coated with a chemical called “Diazo” that changes when exposed to light. Images from the computer are used to create film negatives, which are then put over the aluminum plates and exposed to ultraviolet lights. The plate picks up the image of the newspaper page from the negative, with the dark or exposed portions of the plate becoming a magnet for ink. The plate is then put on the printing press roller and inked with water and ink. The ink adheres to the proper areas (text & photos) and is washed away from the non-inked, gray areas by the water. Then a roller (called a blanket roller) will pick up the ink and transfer it to the newsprint. This process of transferring the ink is called "offset" printing, as opposed to direct plate-to-plate letter press printing, which was phased out in 1981. Color printing requires four plates (four-color printing). This
is standard color printing for the industry, both newspapers and
magazines, although an art book or calendar, and some computer printers
can go much higher (perhaps up to six colors). |
