Low-Pressure Plasma; An Alternative Method of Cleaning Historical Silver Coins

Document Type : Original Article

Authors

1 Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran, 1983963113, Iran

2 The Research Institute of Cultural heritage and Tourism, Tehran, Tehran, 1136913431, Iran

Abstract

Cold plasma treatment is a green technology for cleaning and surface decontamination in various applications. The work in the present paper discusses the use of high-frequency cold plasma for the removal of corrosion products and surface deposits from historical silver coins. The coins, conserved by the Cultural Heritage Organization of Iran, are of the Parthian period and are of significant historical and cultural value. Cold plasma is non-invasive in nature and efficient, with various advantages over traditional cleaning methods. In an attempt to quantify the elemental composition of the coin surfaces, X-ray fluorescence (XRF), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) were performed. The success of the treatment using the plasma was later analyzed by gravimetry, optical microscopy, and comparative imagery. The results indicated a significant reduction in the surface deposits, as confirmed by the measurements of the weights as well as by the microscope. The before-and-after imagery also indicated the improvement in the clarity of the coin designs, which were originally obscured by the contamination. These findings indicate that the treatment with cold plasma is a promising, non-invasive technique for the restoration of historical metal artifacts, which restores the surface features of the artifacts with minimal risk of damage.

Keywords

Pioneering Advances in Materials
Volume 1, Issue 1
January 2026
Pages 22-32

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