Atmospheric corrosion of patinated silverwork: a conservation challenge

Isabel Tissot , Olinda C. Monteiro, Maria Alexandra Barreiros, Maria Guerra

Research output: Contribution to journalArticlepeer-review

Abstract

Patination has been frequently used by jewellers to modify the colour of silver alloys. By application of a solution of sulphur compounds, blackish or bluish surfaces can be obtained, but the intentionally produced silver-sulphur compounds are chemically similar to the atmospheric corrosion products that develop on silver alloys. The conservation of patinated silver objects, such as Art Nouveau jewellery, raises thus analytical challenges. In order to define accurate conservation treatments, the patina and corroded surfaces characterisation is mandatory. In this study, sterling silver samples were patinated and subjected to corrosion by immersion in a sulphide containing solution. The identification of the chemical compounds present on the patinated sterling silver before and after corrosion was carried out by UV-visible spectrophotometry, X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectrometry. Data obtained suggest a two-stage corrosion process: a decrease of the silver compounds patina thickness caused by its dissolution, followed by the formation of corrosion products with different compositions and morphologies containing silver and copper sulphur compounds.
Original languageEnglish
Pages (from-to)15-19
Journal Corrosão e Protecção de Materiais
Volume35
Issue number2
DOIs
Publication statusPublished - 2016

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