Rotogravure printing is a printing process that involves engraving the image onto a copper cylinder, like offset and flexography; it uses a rotary printing press. Gravure printing is characteristically used for long run, high quality printing producing a sharp, fine image. It is most often used for very long runs of up to a million or more.
A rotogravure printing press has one printing unit for each color. There are five basic components in each color unit: an engraved, an ink fountain, a doctor blade, an impression roller, and a dryer. While the press is in operation, the engraved cylinder is partially immersed in the ink fountain, filling the recessed cells. As the cylinder rotates, it draws ink out of the fountain with it. Acting as a squeegee, the doctor blade scrapes the cylinder before it makes contact with the paper, removing ink from the non-printing areas.
Next, the paper gets sandwiched between the impression roller and the gravure cylinder. This is where the ink gets transferred from the recessed cells to the paper. The purpose of the impression roller is to apply force, pressing the paper onto the gravure cylinder, ensuring even and maximum coverage of the ink. Then the paper goes through a dryer because it must be completely dry before going through the next color unit and absorbing another coat of ink.