Where does etching collide?

Etching as an intaglio printmaking process appeared in the early 1500s, with Daniel Hopfer among its first practitioners: the artist coats a metal plate with an acid-resistant ground, draws through the ground with a needle, and immerses the plate in acid, which bites the exposed lines so they hold ink and print as an image. Bosse's 1645 Traité des manières de graver en taille douce was the first systematic manual of the technique, and Hind's 1923 A History of Engraving and Etching remains the standard history. The referent here is a way of making a picture, judged as an artwork and catalogued by states and impressions, not a fabrication step in a microchip or a surface preparation in a tooth.[1][2]

Unit

One etched plate and the impressions pulled from it, described by its states

Recovery means

Not applicable

Measured by

Assessed by connoisseurship of line and tone, and catalogued by state and impression

Buonocore's 1955 paper A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces introduced acid etching in dentistry: a brief application of phosphoric acid to tooth enamel dissolves a shallow layer and leaves a microscopically rough surface into which a resin flows and locks, giving a durable bond. This became the basis of modern adhesive dentistry, from sealants to composite fillings and bonded restorations. Here the referent is a chairside surface treatment that prepares enamel for bonding, measured by bond strength, not a printmaking process or a patterning step in silicon.[3]

Unit

One etched enamel surface prepared for bonding

Recovery means

Not applicable

Measured by

Quantified by resin-to-enamel bond strength and by microscopy of the etched surface

Robbins and Schwartz's 1959 study Chemical etching of silicon characterised how mixtures of hydrofluoric and nitric acid dissolve silicon, one of the founding results of wet etching in microfabrication: etching selectively removes material from a substrate, so that with a protective mask it transfers a pattern into the wafer. Later plasma or dry etching extended the same idea to gas-phase attack for finer features. The referent is a fabrication step that shapes a semiconductor device, measured by etch rate, depth, and selectivity, not a way of making a print or of roughening a tooth for bonding.[4]

Unit

One etch step removing material from a substrate

Recovery means

Not applicable

Measured by

Characterised by etch rate, etch depth, anisotropy, and selectivity to the mask