Surface investigation of some medieval silver coins cleaned in high-frequency cold plasma

Ioanid, Emil Ghiocel; Ioanid, Aurelia; Rusu, D.; Doroftei, Florica

doi:10.1016/j.culher.2010.09.004

Cited by 26 publications

(16 citation statements)

References 6 publications

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“…With this premise some scientific studies about the effectiveness of cleaning methods have been carried out on abrasives [6,7], thiourea-acid solutions [8], electrochemical galvanic cells [20], electrochemical reductions [21,22] and new treatments such as laser [23,24], cold plasma [25], or UV/ozone treatment [26]. However, results of different methods are difficult to compare since they have not been systematically evaluated in similar conditions and materials.…”

Section: Introductionmentioning

confidence: 99%

A comparative study of cleaning methods for tarnished silver

Palomar

Barat

Garcia

et al. 2016

Journal of Cultural Heritage

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a b s t r a c tTarnishing is produced by reaction of silver with gaseous reduced sulphur compounds from atmospheric pollution. It induces the formation of Ag 2 S crystals which produce a dark appearance. To remove sulphur tarnishing, different mechanical, chemical and electrochemical methods have been traditionally used. To assess the effect of different cleaning treatments on tarnished silver, coupons of pure and sterling silver (92% Ag/8% Cu) were subjected to six cycles of induced tarnishing and cleaning. The cleaning methods evaluated were mechanical (soft abrasives and rubber point mounted on a rotary tool); chemical (chelating and acid solutions) and electrochemical (potentiostatic reductions). Surface morphology, composition, weight, color and luminosity were evaluated by optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy and colorimetry. The cleaning impact on tarnished silver depended on the cleaning procedure and the composition of silver. Mechanical treatments restored the original visual appearance of silver although they produced a significant mass loss and a fast re-tarnishing. Chemical cleaning methods were fast; nevertheless the surface appeared completely attacked. Electrochemical cleaning did not yield good result for sterling silver, but was an effective cleaning method for pure silver coupons. Different cleaning methods have been used for many years to remove sulphur tarnishing from silver. However, scientific studies which assess the treatment's impact on silver and the re-tarnishing rate are very scarce. Costa [1] carried out a complete bibliographic study about the cleaning procedures and their applications, although the results of these different scientific works are difficult to compare since they have not been systematically evaluated in similar conditions and materials.The aim of this study is to quantitatively assess the efficiency, residues left on the metal and impact on the base metal of eleven mechanical, chemical and electrochemical cleaning methods to remove tarnishing on pure and sterling silver. To evaluate the effect in the long term, several cycles of tarnishing/cleaning are considered.

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Section: Introductionmentioning

confidence: 99%

A comparative study of cleaning methods for tarnished silver

Palomar

Barat

Garcia

et al. 2016

Journal of Cultural Heritage

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“…Thus the new metal surface that is produced after cleaning is left in the chamber to have the protective coating applied to it. Other researchers [37,38] have successfully employed plasma to reduce corrosion products from the surface of silver artefacts.…”

Section: Disadvantages Of Thiol Fi Lmmentioning

confidence: 99%

Ancient silver artefacts: corrosion processes and preservation strategies

Vassiliou

Gouda

2013

Corrosion and Conservation of Cultural Heritage Metallic Artefacts

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“…Reduction of surface roughness indicated the ability of plasma treatment to clean and remove the contaminants (such as oxides growing on metal wire surface as well as surface exposure to ambient atmosphere) from metal wire surface [1]. Qualitatively, the removal of contaminants should lead to improved morphology of metal wire in terms of producing shinier surface, as a result of oxide removal [24]. Based on the current situation, air temperature measurement and monitoring are required in cold plasma treatment for metal wire surface cleaning for the sake of deep understanding of physical process in plasma cleaning process.…”

Section: Introductionmentioning

confidence: 99%

Air Temperature Measurement and Monitoring Inside Cold Plasma Treatment Reactor for Steel Wire Surface Cleaning Using Fiber Bragg Grating (FBG)

Misnal¹,

Redzuan²,

Zainal³

et al. 2020

ARFMTS

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Surface cleaning is one of the critical preliminary process in wire manufacturing surface treatment for the purpose of improved surface wettability and adhesion. However, concern in terms of environmental impacts arises due to common practices of wetchemicals which led to severe human health. Surface cleaning using cold plasma treatment might become an alternative, but it seems that the issue of gas temperature measurement and monitoring have not been dealt with in depth, since the gas temperature can indicate the type of plasma formed inside the designed reactor. Fiber Bragg grating (FBG) might became an option for gas temperature measurement and monitoring. In this research, air temperature in cold plasma treatment reactor was measured and monitored using FBG, with effects of graphene electrode. Surface roughness of metal wire surface was measured and qualitative observation through optical microscope was carried out, before and after plasma treatment for the purpose of performance evaluation. From the results, it is found that type of plasma discharge formation has been successfully identified through air temperature profiling and monitoring using FBG. Highest surface roughness reduction is performed by filamentary type of discharge of 9 kV applied voltage based on generated air temperature profile by FBG.

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Surface investigation of some medieval silver coins cleaned in high-frequency cold plasma

Cited by 26 publications

References 6 publications

A comparative study of cleaning methods for tarnished silver

A comparative study of cleaning methods for tarnished silver

Ancient silver artefacts: corrosion processes and preservation strategies

Air Temperature Measurement and Monitoring Inside Cold Plasma Treatment Reactor for Steel Wire Surface Cleaning Using Fiber Bragg Grating (FBG)

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