An evolution of lithography, offset printing is based on the principle that water and grease do not mix,Offset plates are usually made of zinc, aluminum, or a combination of metals, treated to make the surface porous, and then coated with a photosensitive material. Exposure to the image cures the coating in the printed areas. The coating in non-printing areas washes away, leaving behind a damp metal that repels ink .
Digital printing is the system of printing virtual-primarily based totally pictures without delay onto quite a few media substrates. There isn't anyt any want for a printing plate, in contrast to with offset printing. Digital documents together with PDFs or computing device publishing documents may be despatched without delay to the virtual printing press to print on paper, image paper, canvas, fabric, synthetics, cardstock and different substrates.