Although there are many different kinds, sizes and qualities of offset presses, the basic configuration remains the same. When the printing plate is exposed, an ink-receptive coating is activated at the image area. On the press, the plate is dampened, first by water rollers, then by ink rollers. Ink adheres to the image area and water to the non-image area. As the cylinders rotate, the image is transferred to the blanket.
Paper passes between the blanket cylinder and the image is transferred to the paper.
The major types of offset presses are sheetfed and web. In a sheetfed press, cut paper is delivered into the machine. In a web press, paper comes on a large roll and is cut after printing. Uncompetitive at shorter runs, it is most commonly used for the production of newspapers, magazines and cataloges due to its speed and economy at runs over 250,000. Formerly the standard printing process, letterpress is now largely used for specialty work such as fine art prints, books and posters.