Engravers used a range of techniques and tools to make various marks on the metal printing plate. When printed, these marks appeared as different types of line, each with their own identifying characteristics.
Large tonal areas such as skies are often described with multiple cross-hatched lines.
Etched lines are drawn through a waxy ground onto the metal plate. The plate is dipped in acid which bites the lines into the metal. Etched lines have blunt, rounded ends.
An engraved line is cut directly into the metal printing plate, using a sharp tool called a burin. This produces a fine line which tapers to a point at the end.
Mezzotints are also made on metal plates, but the process uses tiny dots to create areas of tone instead of lines. The image is worked from dark to light, and has a characteristic velvety softness.