Ink and Water
Offset printing is based on a very simple principle: ink and water don't mix. Text and pictures are imaged onto printing plates, which are dampened first by water, then ink. Because water and ink repel one another, the ink adheres to the image area, the water to the non-image area. Next, the image offsets from the plate to a rubber blanket, and again from the rubber blanket to the paper. We call this process "offset" because throughout the process, the plate never directly touches the paper.