Horn Silver. A type of tarnish, silver chloride, formed on the surface of silver exposed to hydrogen chloride. Characteristically horn silver is a white to pale-yellow or gray color and in natural state is cerargyrite (AgCl). Removing a tough tarnish like horn silver is difficult, as no chemicals can dissolve it. Extensive horn silver needs to be removed physically, the best is by reverse electroplating. Such reverse plating, however, removes not only the tarnish but also the top layer of silver. Physical removal can also be accomplished by sandblast or abrasive blast, or by light pickling with sulfuric acid. Needless to say, it should only be done by a professional.
excerpted with permission from
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor