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Silver Plating On Copper, Bronze And Brass

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Abstract

Silver has generally been valued second only to gold from at least as early as 2000BC. A material which is highly prized becomes a status symbol and cheaper imitations find a ready market. Craftsmen very early developed methods of applying thin layers of silver onto base metal as an economical use of precious metal, whether for its decorative effect or, particularly in the case of plated coins, to deceive the customer. Unfortunately, silver plating is less commonly preserved than gold plating, and corrosion at the interface between the silver and base metal may destroy the evidence of how the plating was applied. The situation is complicated because many of the white metal surfaces on pieces labelled as ‘silvered’ are in fact produced by tin, or more rarely, by arsenic. Nevertheless, there are still sufficient surviving examples to indicate that silver plating has a long history during which techniques were developed to give better results and to allow more economical use of the precious metal.
... On this gold-colored surface, silver scrolls of vine, shaped by repoussé, are applied with soft solder: a tin-lead alloy that can have different proportions of the two metals ( Fig. 6 ). A similar technique was used in Roman times for small decorative objects, such as statuettes, in imitation of more expensive silver items ( Giumlia-Mair 2001 :770;La Niece 1990a ). ...
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... The concentration of Hg in this case is similar to that of the earlier documents that reported 8-25% Hg in the gilded layer (Anheuser 1997;Yang et al. 2014); however, the Hg concentrations in the silvered layer were higher than those in the gilded layer. This reveals that the evaporation of Hg in the silvered layer is obviously lower than that in the gilded layer due to low baking at a temperature of about 357°C, as proved in the literature (Williams 1977;La Niece 1990;Trojek and Hložek 2012). The gilded and silvered layers were explored before their patinas were removed; the patina surface was the original surface covered with green corroded products. ...
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... Other types of silvering have been also observed, producing a very thin precipitation of pure silver. Various recipes have been tested, all based on the application of pastes and solutions (Daniel 1969;La Niece 1990;La Niece 1993;Anheuser & France 2002). The mechanism is electro-chemical and occurs when there is an electro-differential between the solution and the metal to be plated. ...
... The surface XRF technique is not indicated to determine the bulk content because of the expected heterogeneity of the alloy (Carter 1977, Lutz and Pernicka 1996). Evidence of thin silver enriched patina has been found (Cope 1972, Vlachou 2002, La Niece 1990, Pappalardo et al. 2003). In the present work we propose a method, based on nondestructive and portable PIXE and XRF surface analytical techniques, to study and characterize the thin-surface layer of Roman folles. ...
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Methods of Gilding and Silvering before 1850
  • T G Padley