About 1420, Gutenberg invented printing with movable type. The method he used was not improved upon basically until Senefelder invented lithography 380 years later. With both of these methods (letterpress and lithography), the ink is transferred to the type or plate through a soft pad or rubber roll. The ink is a viscous material that forms a thick coating on the pads or rubber rolls. In many cases, the density of the ink on the substrate is controlled by a set of keys located in the fountain. These control the amount of ink released from the fountain to the ink rolls. More recently, the soft applicator rolls have been replaced with metal rolls having an engraved surface. These are called anilox rolls. Anilox rolls are part of the flexographic press and carry the ink in measured quantities to the printing plates.