The acid "bites" into the metal (it undergoes a redox reaction) to a depth depending on time and acid strength, leaving behind the drawing carved into the wax on the plate. The plate is then dipped in a bath of acid, known as the mordant ( French for "biting") or etchant, or has acid washed over it. The échoppe, a tool with a slanted oval section, is also used for "swelling" lines. The artist then scratches off the ground with a pointed etching needle where the artist wants a line to appear in the finished piece, exposing the bare metal. In traditional pure etching, a metal plate (usually of copper, zinc or steel) is covered with a waxy ground which is resistant to acid. In a number of modern variants such as microfabrication etching and photochemical milling it is a crucial technique in much modern technology, including circuit boards. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In modern manufacturing, other chemicals may be used on other types of material. Įtching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal.
His most important contribution in the history of printmaking was his transformation of the 17th-century etching process from a hitherto relatively new craft into a truly admired art form in subsequent centuries, especially in the 19th century. Rembrandt is generally considered the greatest etcher in the history of the medium (as an art in its own right). Christ Preaching, known as The Hundred Guilder Print, an etching by Rembrandt (c. 1648).