Etching

In traditional pure etching, a metal plate (usually of copper, zinc or steel) is covered with a waxy ground which is resistant to acid.

The process can be repeated many times; typically several hundred impressions (copies) could be printed before the plate shows much sign of wear.

They were made according to a technique of alkaline etching developed by the Harappans, and vast quantities of these beads were found in the archaeological sites of the Indus Valley civilization.

Etching by goldsmiths and other metal-workers in order to decorate metal items such as guns, armour, cups and plates has been known in Europe since the Middle Ages at least, and may go back to antiquity.

The elaborate decoration of armour, in Germany at least, was an art probably imported from Italy around the end of the 15th century—little earlier than the birth of etching as a printmaking technique.

Apart from his prints, there are two proven examples of his work on armour: a shield from 1536 now in the Real Armeria of Madrid and a sword in the Germanisches Nationalmuseum of Nuremberg.

[13] The switch to copper plates was probably made in Italy,[14] and thereafter etching soon came to challenge engraving as the most popular medium for artists in printmaking.

Jacques Callot (1592–1635) from Nancy in Lorraine (now part of France) made important technical advances in etching technique.

One of his followers, the Parisian Abraham Bosse, spread Callot's innovations all over Europe with the first published manual of etching, which was translated into Italian, Dutch, German and English.

To apply hard ground of this variety, the plate to be etched is placed upon a hot-plate (set at 70 °C, 158 °F), a kind of metal worktop that is heated up.

The detritus is powdery dissolved metal that fills the etched grooves and can also block the acid from biting evenly into the exposed plate surfaces.

This will show the printmaker the different degrees or depths of the etch, and therefore the strength of the ink color, based upon how long the plate is left in the acid.

Growing concerns about the health effects of acids and solvents[19][20] led to the development of less toxic etching methods[21] in the late 20th century.

Others, such as printmakers Mark Zaffron and Keith Howard, developed systems using acrylic polymers as a ground and ferric chloride for etching.

The traditional aquatint, which uses either powdered rosin or enamel spray paint, is replaced with an airbrush application of the acrylic polymer hard ground.

The ink receives impressions like traditional soft ground, resists the ferric chloride etchant, yet can be cleaned up with warm water and either soda ash solution or ammonia.

Copper is a traditional metal, and is still preferred, for etching, as it bites evenly, holds texture well, and does not distort the color of the ink when wiped.

This wearing out of the image over time is one of the reasons etched prints created early in a numbered series tend to be valued more highly.

Prior to 1100 AD, the New World Hohokam culture independently utilized the technique of acid etching in marine shell designs.

It can be applied after polishing to further reveal microstructural features (such as grain size, distribution of phases, and inclusions), along with other aspects such as prior mechanical deformation or thermal treatments.

Particulate resin is evenly distributed on all or parts of the plate, then heated to form a screen ground of uniform, but less than perfect, density.

Successive turns of varnishing and placing the plate in acid create areas of tone difficult or impossible to achieve by drawing through a wax ground.

Designs in a syrupy solution of sugar or Camp Coffee are painted onto the metal surface prior to it being coated in a liquid etching ground or 'stop out' varnish.

A mixture of nitric acid and gum arabic (or, very rarely, saliva) which can be dripped, spattered or painted onto a metal surface giving interesting results.

Zinc is also used, because as a softer metal, etching times are shorter; however, that softness also leads to faster degradation of the image in the press.

Foul-bite or "over-biting" is common in etching, and is the effect of minuscule amounts of acid leaking through the ground to create minor pitting and burning on the surface.

This incidental roughening may be removed by smoothing and polishing the surface, but artists often leave faux-bite, or deliberately court it by handling the plate roughly, because it is viewed as a desirable mark of the process.

[34] It was also referenced in Dashiell Hammett's 1934 novel The Thin Man, in which the narrator answers his wife asking him about a lady he had wandered off with by saying: "She just wanted to show me some French etchings.

"[35] The phrase was given new popularity in 1937: in a well publicized case, violinist David Rubinoff was accused of inviting a young woman to his hotel room to view some French etchings, but instead seducing her.

As early as 1895, Hjalmar Söderberg used the reference in his "decadent" début novel Delusions (swe: Förvillelser), when he lets the dandy Johannes Hall lure the main character's younger sister Greta into his room under the pretence that they browse through his etchings and engravings (e.g., Die Sünde by Franz Stuck).