Altération et nettoyage de pièces en argent doré

Degrigny, Christian; Wéry, M.; Vescoli, V.; Blengino, J. M.

doi:10.1179/sic.1996.41.3.170

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…This electrolyte is a good conductor and does not chemically attack the metals. It has been used for electrochemical cleaning of tarnished silver objects . The measurements are performed with a Palmsens potentiostat/galvanostat.…”

Section: Methodsmentioning

confidence: 99%

How effective are reducing plasma afterglows at atmospheric pressure in removing sulphide layers: Application on tarnished silver, sterling silver and copper

Schalm

Storme

Gambirasi

et al. 2017

Surface & Interface Analysis

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A plasma afterglow from a gas mixture of 5 vol% H 2 in He is able to remove tarnish layers on pure silver in a matter of seconds. This dry, localized, and noncontact cleaning technique is a promising method to clean historical objects where silver is combined with organic materials and where traditional cleaning techniques are not recommended. However, historical objects are often manufactured with silver alloys but somehow their tarnish layers are removed less effectively with plasma treatments. To understand the different impact of the afterglow, the surfaces of corroded silver, sterling silver, and copper coupons are characterized before and after plasma treatment by a multianalytical approach combing optical and confocal microscopy, scanning electron microscopy coupled to energy dispersive X-ray analysis and chronopotentiometry. The analyses demonstrate that the few hundred nanometre-thick tarnish layer on pure silver is transformed through the whole thickness resulting in a porous metallic film. On top of that metallic film, some isolated remnant Ag 2 S particles are found. For sterling silver, a yellowing of the surface occurs. The Ag-rich corrosion products are reduced to a large extent, while the Cu-rich corrosion products are only partially reduced. For corroded copper, no apparent visual change is observed at a macroscopic scale, although the morphology of the surface changed. The results allow an evaluation of the cleaning efficiency and provide a deeper understanding of hydrogen plasma effects on the transformation of sulphide corrosion layers at atmospheric pressure.

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Section: Methodsmentioning

confidence: 99%

How effective are reducing plasma afterglows at atmospheric pressure in removing sulphide layers: Application on tarnished silver, sterling silver and copper

Schalm

Storme

Gambirasi

et al. 2017

Surface & Interface Analysis

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“…Tarnished silver objects are often cleaned mechanically but the relief of the decoration made it difficult to apply a mechanical treatment. Electrochemical treatments thus provided a good alternative [ 35 ]: First, the silver sulfides were reduced to silver at −0.89 V/SCE (saturated calomel electrode), then the reduced silver deposited on the gilding was oxidized at +0.66 V/SCE to reveal the gilding. However, since the dagger is a composite object, the ivory parts could not be immersed.…”

Section: Resultsmentioning

confidence: 99%

The Use of Hydrogels in the Treatment of Metal Cultural Heritage Objects

Guilminot

2023

Gels

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Currently gels are widely used in the restoration of paintings, graphic arts, stuccowork and stonework, but their use in metal restoration is less widespread. In this study, several polysaccharide-based hydrogels (agar, gellan and xanthan gum) were selected for use in metal treatments. The use of hydrogels allows to localize a chemical or electrochemical treatment. This paper presents several examples of treatment of metal objects of cultural heritage, i.e., historical or archaeological objects. The advantages, disadvantages and limits of hydrogel treatments are discussed. The best results are obtained for the cleaning of copper alloys via associating an agar gel with a chelating agent (EDTA (ethylenediaminetetraacetic acid) or TAC (tri-ammonium citrate)). The hot application allows to obtain a peelable gel, particularly adapted for historical objects. Electrochemical treatments using hydrogels have been successful for the cleaning of silver and for the dechlorination of ferrous or copper alloys. The use of hydrogels for the cleaning of painted aluminum alloys is possible but it has to be coupled with mechanical cleaning. However, for the cleaning of archaeological lead, the cleaning using hydrogels was not very effective. This paper shows the new possibilities of using hydrogels for the treatment of metal cultural heritage objects: agar is the most promising hydrogel.

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“…A light burnishing of the surface restores the metallic luster. The treatment is carried out by immersion, either in sodium sesquicarbonate (or trisodium hydrogendicarbonate -Na 3 H(CO 3 ) 2 ) 5% by weight (alkaline) , Degrigny & Jérôme, 1993, or in sodium nitrate buffered with citrate -NaNO 3 1% by weight (slightly acidic) (Degrigny et al, 1996). In the alkaline electrolyte, an anode of stainless steel grid is used while a more expensive but corrosion resistant platinum (Pt) mesh is necessarily employed for neutral electrolytes.…”

Section: Introductionmentioning

confidence: 99%

A new electrolytic pencil for the local cleaning of silver tarnish

Degrigny

Jeanneret

Witschard³

et al. 2016

Studies in Conservation

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The prototyping of a newly designed electrolytic pencil for the local cleaning of silver tarnish on artifacts comprising inseparable organic components is described. The pencil helps determine the type and amount of tarnish, define the cleaning parameters (treatment potential and duration), and provides a safe and efficient way to locally and electrolytically reduce silver tarnish. The electrolyte is conveyed to and from the surface of metal objects via a micro-porous foam and is continuously renewed by two pumps. This user-friendly and ergonomic pencil is distributed as an open source kit for self-assembly with parts fabricated using innovative and low-cost technologies. The operating modes for the pencil are described. To evaluate this new tool, the pencil was used to clean a selection of tarnished silver components from composite masterpieces in the Treasury of Saint-Maurice Abbey.

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Altération et nettoyage de pièces en argent doré

Cited by 5 publications

References 9 publications

How effective are reducing plasma afterglows at atmospheric pressure in removing sulphide layers: Application on tarnished silver, sterling silver and copper

How effective are reducing plasma afterglows at atmospheric pressure in removing sulphide layers: Application on tarnished silver, sterling silver and copper

The Use of Hydrogels in the Treatment of Metal Cultural Heritage Objects

A new electrolytic pencil for the local cleaning of silver tarnish

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