The Art of Etching
While the use of acid to etch metal was first developed in Arabia in the Middle Ages—as a technique to add decoration to weapons—it would not be employed for printing on paper until the late 15th century.
Widely popularized in southern Germany, etching soon competed with engraving as a printmaking medium. Unlike engraving, it required little knowledge of metalworking and could be practiced by artists trained only in drawing. What’s more, etching provided more artistic freedom in creating lines, as if they were drawn with a pen, as opposed to engraving, which favored straight lines.
Even so, early line etchings showed little depth or expression since they were drawn with a single point at a uniform depth in flat iron plates. As the use of acids or mordants (from Latin, mordere, to bite) became more predictable, artists began to “bite” lines for different amounts of time to create gradation. And with the introduction of copper as an etching medium, the practice of scraping and burnishing the softer metal provided even more freedom of expression.
The Etching Process
- The metal plate—usually copper, steel or zinc—is covered with a thin acid-resistant layer known as the etching ground.
- Using an etching needle, a design is drawn into the ground, exposing the bare metal.
- The plate is placed in an acid bath, which produces grooves where the surface of the metal is not protected. The longer the plate is left in the bath, the more the acid eats into the metal—creating deeper grooves.
- Gradations in the lines can be created by selectively applying an acid-resistant varnish before the plate is replaced in the bath.
- The plate is removed from the acid bath and the etching ground is removed, revealing the design of the etching.
- Ink is applied to the clean plate with an ink-pad or roller and then wiped clean—so that only the etched areas contain ink.
- A damp sheet of paper is laid on the plate and then pressed between the rollers of an etching press, transferring the ink in the design to the paper.