Offset lithography is primarily used for medium and long print runs of books, posters, packaging and magazines. It is commonly used for the bulk of mass printing production used by various types of businesses and organizations. According to Printing For Less, it is the standard commercial printing method used worldwide since the 20th century.
In offset lithography, ink and water do not mix. This means that the printing plate and paper do not come in direct contact with each other. The process works by transferring the image information, which includes art and/or text, to rubber rollers. The image is placed on thin metal plates that are moistened by ink and water by rollers on the press. The water adheres to the non-image area, while the oil-based ink to the image area. The inked region then transfers to a rubber cylinder and goes onto the paper as it moves around the cylinder. Since the image is not directly transferred from the plates to the paper and instead transferred to an intermediary surface, the process is called “offset.”
Generally, the advantages of offset printing are the excellent quality and low price. It is typically a cost-effective option for printing large quantities. It produces high-quality images and photographs with fine details and sharp typefaces.