Etching

Etching is traditionally the process of using strong <a href="/facts/Acid/FySU18n1">acid</a> or <a href="/facts/Mordant/KGkRrkba">mordant</a> to cut into the unprotected parts of a <a href="/facts/Metal/PT8hNX6R">metal</a> surface to create a design in <a href="/facts/Intaglio_(printmaking)/UGGoXppU">intaglio</a> (incised) in the metal. In modern manufacturing, other chemicals may be used on other types of material. As a method of <a href="/facts/Printmaking/9maDzuae">printmaking</a>, it is, along with <a href="/facts/Engraving/0hCX4flU">engraving</a>, the most important technique for <a href="/facts/Old_master_print/7mTEMQVX">old master prints</a>, and remains in wide use today. In a number of modern variants such as <a href="/facts/Etching_(microfabrication)/kPa01dgL">microfabrication etching</a> and <a href="/facts/Photochemical_machining/4H7fXWAK">photochemical milling</a>, it is a crucial technique in modern technology, including <a href="/facts/Circuit_board/muSR2p43">circuit boards</a>.
In traditional pure etching, a metal plate (usually of copper, zinc or steel) is covered with a waxy <a href="/facts/Ground_(etching)/uh5b4bc9">ground</a> which is resistant to acid. 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. The échoppe, a tool with a slanted oval section, is also used for "swelling" lines. The plate is then dipped in a bath of acid, known as the <a href="/facts/Mordant/KGkRrkba">mordant</a> (<a href="/facts/French_language/qe1DnaQh">French</a> for "biting") or etchant, or has acid washed over it. The acid "bites" into the metal (it undergoes a <a href="/facts/Redox/Pyd5RVcj">redox</a> reaction) to a depth depending on time and acid strength, leaving behind the drawing (as carved into the wax) on the metal plate. The remaining ground is then cleaned off the plate. For first and renewed uses the plate is inked in any chosen non-corrosive ink all over and the surface ink drained and wiped clean, leaving ink in the etched forms.
The plate is then put through a high-pressure <a href="/facts/Printing_press/7I3laFE0">printing press</a> together with a sheet of paper (often moistened to soften it). The paper picks up the ink from the etched lines, making a print. The process can be repeated many times; typically several hundred impressions (copies) could be printed before the plate shows much sign of wear. The work on the plate can be added to or repaired by re-waxing and further etching; such an etching (plate) may have been used in more than one <a href="/facts/State_(printmaking)/y2Pd8tLQ">state</a>.
Etching has often been combined with other <a href="/facts/Intaglio_(printmaking)/UGGoXppU">intaglio</a> techniques such as engraving (e.g., <a href="/facts/Rembrandt/LPDxP9XQ">Rembrandt</a>) or <a href="/facts/Aquatint/1tQdocJy">aquatint</a> (e.g., <a href="/facts/Francisco_Goya/yG0aRx0w">Francisco Goya</a>). The French name "eau forte" (lit. "strong water") for the technique and the resulting prints was sometimes used in English.

Etching open-in-new

Etching