The Cleaning of Silver Objects With a Basic  Solution of Sodium Glycinate: A Study on Artificially and Naturally Tarnished Silver

• Published in: Studies in conservation 2021-10, Vol.66 (7), p.375-383
• Main Authors: de Figueiredo Junior, João Cura D'Ars, Asevedo, Samara Santos, de Souza e Silva, Maria Luiza Seixas, Araújo, Andrezza Conde, Quites, Maria Regina Emery
• Format: Article
• Language: English
• Subjects: scanning electron microscopy; Silver cleaning; silver tarnish layers; sodium glycinate; X-ray fluorescence
• ISSN: 0039-3630; 2047-0584
• DOI: 10.1080/00393630.2020.1859876

The appearance of silver objects deteriorates due to the formation of a brown-to-black tarnish layer. Several methods are available for removing these tarnished layers, ranging from polishing through chemical cleaning to electrochemical methods. This study presents a low-cost and low-toxicity method that uses sodium glycinate to clean silver. Cleaning tests were performed on both artificially tarnished prototypes and naturally tarnished objects after characterizing them; scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) were used to characterize the artificially tarnished prototypes, and X-ray fluorescence (XRF) was used to characterize the naturally tarnished objects. The aggressiveness of the baths was analyzed by measuring the leached amount obtained through atomic absorption spectroscopy (AAS) and SEM. The procedures used for cleaning the artificially tarnished prototypes served as a guide for cleaning two naturally tarnished objects: a halo and a crown. Cleaning was guided by the presented method's characteristics as well as the object's unique characteristics and condition.