Offsettrükiplaadidel

Offsettrükiplaadid, also known as lithographic plates, are a fundamental component in the offset printing process. These plates are typically made from thin sheets of aluminum, though other materials like zinc or polyester can also be used. The surface of the plate is treated to create distinct areas that either attract or repel ink, which is the basis of lithography.

The image or text to be printed is transferred onto the plate through a photographic or digital process. In traditional methods, a film positive is placed on the plate, and exposure to UV light hardens the image areas, making them ink-receptive (oleophilic). The non-image areas are treated to become water-receptive (hydrophilic). In modern computer-to-plate (CTP) systems, the image is directly etched onto the plate by a laser, eliminating the need for film.

During the printing process, the plate is dampened with water, which adheres only to the non-image areas. Ink is then applied, and it adheres only to the image areas, which have been treated to repel water. The inked image is then transferred from the plate to a rubber blanket, and finally from the blanket to the paper or substrate. This indirect transfer is what gives offset printing its name. Offsettrükiplaadid are designed for multiple runs and can produce high-quality images with sharp details and consistent color.