For anyone else that had no idea what a mezzotint was: Wikipedia

Mezzotint is a monochrome printmaking process of the intaglio family. It was the first printing process that yielded half-tones without using line- or dot-based techniques like hatching, cross-hatching or stipple. Mezzotint achieves tonality by roughening a metal plate with thousands of little dots made by a metal tool with small teeth, called a "rocker". In printing, the tiny pits in the plate retain the ink when the face of the plate is wiped clean. This technique can achieve a high level of quality and richness in the print, and produce a furniture print which is large and bold enough to be framed and hung effectively in a room.