main printed feature: intaglio
Illustrations that have been printed from copper plates with lines inscribed in them belong to the category of “intaglio” prints (the “g” is silent: in-TAH-lee-oh). Such prints might be engravings, in which the lines are carved out of the plate with a burin, or etchings, in which acid is used to create the lines. They are categorized here together because the printing process is the same for both.