Effects of cleaning procedures on the long-term corrosion behavior of bronze artifacts of the cultural heritage in outdoor environment

Petiti, Chiara; Toniolo, Lucia; Gulotta, Davide; Mariani, Bruna Bueno; Goidanich, Sara

doi:10.1007/s11356-020-07814-4

Cited by 23 publications

(21 citation statements)

References 28 publications

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“…Three weeks after the treatment, a general increase in Rp values was measured, confirming the suitability and the effectiveness of the cleaning methodology and suggesting a general stabilisation and improvement of the protectiveness provided by the corrosion layers left on the surface. The few data available in literature regarding the corrosion behaviour of surfaces after cleaning generally report a moderate decrease of Rp immediately after cleaning, suggesting a temporary reactivation of the surfaces [11,34,35]. In the present case, the electrochemical measurements were not performed immediately after cleaning, and probably the 3 weeks elapsed between the cleaning and the Rp analysis allowed achieving a stabilisation of the patina higher than before the intervention.…”

Section: Type Of Cloth or Sponge For Lpr And Eis Measurementsmentioning

confidence: 59%

Optimisation of the setup of LPR and EIS measurements for the onsite, non-invasive study of metallic artefacts

Petiti

Gulotta

Mariani³

et al. 2020

J Solid State Electrochem

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Electrochemical techniques have been successfully applied in the past as non-destructive techniques to the cultural heritage field. In particular, linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS) have been employed for the onsite monitoring of corrosion on metallic works of art, providing valuable results. Such techniques have been successfully adapted from the industrial field for this particular kind of application, but a systematic evaluation of the influence of all experimental settings on the obtained results is still lacking: several factors and parameters can affect the results, and it is important to properly consider their influence for a reliable interpretation of data. Therefore, in this work, the influence of a series of experimental parameters was evaluated in order to obtain a reliable and time-effective setup by performing a series of tests on a bronze artefact. Several variables were considered, with particular attention to those affecting the reproducibility and reliability of the measurements, as well as the duration of each single acquisition. It was demonstrated, in fact, that an optimised experimental setup from the point of view of the duration could improve also reproducibility and reliability of the measurements. The optimised protocol was then adopted in the framework of a diagnostic campaign of the Monumento ai Caduti (War Memorial) of Lecco (IT)

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Section: Type Of Cloth or Sponge For Lpr And Eis Measurementsmentioning

confidence: 59%

Optimisation of the setup of LPR and EIS measurements for the onsite, non-invasive study of metallic artefacts

Petiti

Gulotta

Mariani³

et al. 2020

J Solid State Electrochem

Self Cite

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“…Based on the Sku kurtosis parameter, it was observed which abrasives give a beneficial effect in the cleaning process. In References [ 9 , 30 ], it is recommended that height parameters should be considered together with kurtosis, because not only the depth of the surface profile recesses but also their shape determines the concentration of stress.…”

Section: Resultsmentioning

confidence: 99%

“…High financial outlays, required to protect metals against corrosion, are the result of a number of activities thanks to which corrosion processes are stopped or, to a significant extent, delayed. References [ 28 , 29 , 30 ] present the problem of cleaning machine parts and methods of their protection. At last, the sources of corrosion processes and corrosion prevention methods were evaluated in References [ 31 , 32 , 33 , 34 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Abrasive-Type Influence on the Effectiveness of Rotary Cleaning of Machine Parts with Complex Geometric Features

2020

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This work presents the analysis of functional relationships between fraction size of abrasives and geometric parameters of surfaces after rotary cleaning. The influence of an abrasive type on the effectiveness of rotary cleaning of machine parts with complex geometric features was determined as well. The process of mechanical cleaning, using a rotational method, of clutch springs was performed in the proprietary device for rotational cleaning, which was followed by the computer-aided analysis of the obtained results. The research process was carried out using abrasive materials such as grinding stone, sand, basalt, glass, and fine gravel, and the test samples were clutch springs after eight years of operation. Based on calculated three-dimensional (3D) roughness values of the cleaned samples’ surfaces, qualitative classification of abrasives was determined. The most effective material turned out to be fine gravel, while the worst results were related to basalt usage.

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“…This treatment uses specific, tunable laser parameters such as wavelength, as well as pulse frequency and duration, to preferentially excite and safely remove undesired coatings or contaminants from a surface through photomechanical, photothermal, and photochemical reactions [3]. Among its successful applications, laser cleaning has proven highly effective for removing corrosion products from bronze sculptures [3][4][5][6][7][8][9] and archaeological objects [10][11][12][13]. One of the main advantages of this cleaning methodology is the possibility to select suitable settings for achieving the expected results, preventing the operator from damaging the artwork [14].…”

Section: Introductionmentioning

confidence: 99%

The Samuel F. B. Morse statue in Central Park: scientific study and laser cleaning of a 19th-century American outdoor bronze monument

2020

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Many of Central Park's bronze statues were coated with lacquer as a protective measure between the late 1970s and early 1990s. In several cases, these coatings outlasted their performance life and were no longer adequately protecting the sculptures. In 2010, a cyclical campaign to remove and refurbish the coatings provided an opportunity to closely assess the condition of de-coated surfaces and to develop suitable, sustainable treatment approaches. The Samuel F. B. Morse statue, created in 1870 by Byron Pickett, commemorates the 19th-century painter and inventor known for the telegraphic code that bears his name. Initially, samples from this statue were collected on the field and analyzed with various techniques to characterize the degradation products that were heavily affecting its surface and the organic coatings used to protect the bronze. Various corrosion species, mainly sulfates and chlorides, were identified by X-ray powder diffraction (XRD), while pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) revealed that the organic coatings were based on mineral wax and acrylics. These results informed a decision to relocate the statue to a controlled workshop space to aid in the manipulation of the large figure and optimize cleaning by laser ablation. Treatment was monitored through three campaigns of analysis using portable X-ray fluorescence (pXRF) spectroscopy, performed on select locations, to characterize the extent of corrosion across the sculpture's surface and monitor changes on the target areas throughout the cleaning. Following the initial phase of treatment, pXRF showed the substantial removal of iron-and lead-rich compounds from the brownish-toned coating and atmospheric pollution deposition. In the subsequent treatment phases, variations in the relative amounts of sulfates and chlorides were noted and further investigated through the examination of a cross section by means of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS). Based on the findings of iron-containing pigments in the organic coating, a decision to apply a new, similar, translucent, brown-toned coating containing such coloring materials was made to achieve the desired visual nuance for the finish and provide additional corrosion protection to the bronze. Scientific analysis on the Morse statue has helped characterize its materials, methods of fabrication, and current conditions on a microscopic scale; in addition, it has guided the means and methodologies of treatment and relays essential information useful for future preservation.

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Effects of cleaning procedures on the long-term corrosion behavior of bronze artifacts of the cultural heritage in outdoor environment

Cited by 23 publications

References 28 publications

Optimisation of the setup of LPR and EIS measurements for the onsite, non-invasive study of metallic artefacts

Optimisation of the setup of LPR and EIS measurements for the onsite, non-invasive study of metallic artefacts

Analysis of the Abrasive-Type Influence on the Effectiveness of Rotary Cleaning of Machine Parts with Complex Geometric Features

The Samuel F. B. Morse statue in Central Park: scientific study and laser cleaning of a 19th-century American outdoor bronze monument

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