Mezzotint

 A form of intaglio engraving where the copper plate is "rocked" with a curved, notched or toothed blade ‘a rocker’ until the surface is entirely pitted. If printed at this stage, an inked pitted plate would print a rich, uniform black. Working from dark to light the printmaker, then uses a scraper or ‘burnisher’ to flatten the raised parts to reduce the ink-holding capacity of areas of the plate; a little for dark grays, a lot for light grays, completely for white (after inking and wiping, the plate holds no ink where it is smooth). Colors are achieved by similarly working one or more supplementary plates. Although Mezzotint is among the most physically demanding mediums in printmaking, no better method has ever been found for expressing tone and texture in monochrome.
The technique was invented by the German Ludwig von Siegen (1609–c1680). The great mezzotint period began around 1750. By then the technique was fully established and became particularly popular in England for reproducing portrait paintings. It is renowned for the soft gradations of tone and richness and velvet quality of its blacks.