How are engraving, etching, drypoint, and mezzotint related?

Engraving, etching, drypoint, and mezzotint are all classified as intaglio processes, which are fundamental techniques in printmaking. They are related by the fact that the printing is done from ink held in recessed areas—incisions, grooves, or textures—below the surface of a metal plate.12

In all these methods, the plate is inked and then wiped clean so that ink remains only in the recesses. Because the paper must be pressed into these crevices to pick up the ink, all four techniques require the use of a roller press to apply the significant pressure necessary to transfer the image.123

While they share this core mechanical principle, they differ in how the image is created:
* Engraving: The design is mechanically incised directly into the plate.14
* Etching: The design is created by using acid to bite lines into the metal surface.14
* Drypoint: The artist scratches the plate with a needle, creating a burr that holds the ink.5
* Mezzotint: The entire plate is roughened to hold ink, and the artist works back toward lighter values by smoothing the surface.67