Lithographic printing, also known as lithography, is a printing technique that involves using a flat surface, typically made of metal, plastic, or stone, to transfer an image onto paper or other materials. The process relies on the principle that oil and water don’t mix.
Here’s a simplified breakdown of how lithographic printing works:
Preparation of the Plate: The printing surface, usually a metal plate coated with a photosensitive emulsion, is prepared. The emulsion is sensitive to light and is applied evenly across the plate.
Image Exposure: A photographic negative or digital image is placed over the plate and exposed to light. Wherever light hits the emulsion, it hardens, creating a pattern of the image on the plate. This process is often done using UV light.
Chemical Treatment: After exposure, the plate is treated with chemicals to develop the image. Areas that were exposed to light become hydrophobic (water-repelling), while the unexposed areas remain hydrophilic (water-attracting).
Inking the Plate: Ink is applied to the plate. The ink adheres only to the hydrophobic areas where the image is, while the hydrophilic areas repel the ink.
Transferring the Image: A rubber roller, called a “blanket,” is rolled over the plate, picking up the ink from the raised areas (where the image is) and transferring it onto the printing surface.
Printing: The printing surface, usually paper, is pressed against the blanket, transferring the ink onto the paper to create the final printed image.
Lithography is widely used for printing books, newspapers, posters, packaging, and many other types of products. It’s known for its ability to produce high-quality, detailed prints with consistent results. Additionally, it’s cost-effective for large print runs once the initial setup is complete.
