Mezzotint

(mezzo= half + tinta= tone), a reverse
engraving process used on a copper or steel plate to
produce illustrations in relief with effects of light and
shadow. The surface of a master plate is roughened
with a tool called a rocker so that if inked, it will
print solid black. The areas to be white or gray in the
print are rubbed down so as nor to take ink. It was
widely used in the 18th and 19th centuries to
reproduce portraits and other paintings, but became
obsolete with the introduction of photo-engraving