Editing Mirror (section)

===Contemporary technologies===
Mirrors are often produced by the wet deposition of silver, or sometimes nickel or chromium (the latter used most often in automotive mirrors) via [[electroplating]] directly onto the glass substrate.<ref name=mlink2014/>

Glass mirrors for optical instruments are usually produced by [[vacuum deposition]] methods. These techniques can be traced to observations in the 1920s and 1930s that metal was being ejected from [[electrode]]s in [[gas discharge lamp]]s and condensed on the glass walls forming a mirror-like coating. The phenomenon, called [[sputtering]], was developed into an industrial metal-coating method with the development of [[semiconductor]] technology in the 1970s.

A similar phenomenon had been observed with [[incandescent light bulbs]]: the metal in the hot filament would slowly [[sublimation (phase transition)|sublimate]] and condense on the bulb's walls. This phenomenon was developed into the method of [[evaporation (deposition)|evaporation coating]] by Pohl and Pringsheim in 1912. [[John D. Strong]] used evaporation coating to make the first [[aluminium]]-coated telescope mirrors in the 1930s.<ref name=matt2004/> The first [[dielectric mirror]] was created in 1937 by Auwarter using evaporated [[rhodium]].<ref name=pulk1999/>

The metal coating of glass mirrors is usually protected from abrasion and corrosion by a layer of paint applied over it. Mirrors for optical instruments often have the metal layer on the front face, so that the light does not have to cross the glass twice. In these mirrors, the metal may be protected by a thin transparent coating of a non-metallic ([[dielectric]]) material. The first metallic mirror to be enhanced with a dielectric coating of [[silicon dioxide]] was created by Hass in 1937. In 1939 at the [[Schott Glass]] company, Walter Geffcken invented the first dielectric mirrors to use multilayer coatings.<ref name=pulk1999/>