Tarnishing (metallurgy)

Tarnishing is the formation of a thin coating on the surface of metals . In humid air, lead and zinc are covered with a thin layer of oxide or carbonic acid salt , a coating of sulfur silver is formed on silver in unclean air , steel is covered with an oxide layer when heated, which depending on its thickness appears yellowish, reddish or blue ( tarnish color ).

Demarcation

When higher temperatures are specifically applied to workpieces , the term tempering is generally used, used in general metal processing for surface finishing and hardening and, in particular, by gunsmiths and gunsmiths for surface finishing of weapons .