Rotogravure printing is a type of intaglio printing process which uses a rotary printing press. It involves engraving an image onto a copper plated steel cylinder base. This image is acid-etched on the surface of the metal cylinder in a pattern of cells. The cells are actually recessed into the cylinder and are of different depth. These cells hold the ink that is transferred to the substrate. While the cells are filled with ink, the non-printing portions of the plate or cylinder are wiped or scraped free of ink. Once the paper or another substrate is pressed against the inked cylinder on a rotary press, the image is transferred directly to the paper. The engraved cylinder sits partially immersed in the ink fountain, where it picks up ink to fill its recessed cells on each rotation of the press.