Characterization of patinas by means of microscopic techniques

Vázquez-Calvo, C.; Buergo, Mónica Álvarez de; Fort, Rafael; Varas, María José

doi:10.1016/j.matchar.2007.04.024

Cited by 42 publications

(25 citation statements)

References 9 publications

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“…Soiling is a visual effect resulting from the darkening of exposed surfaces following the deposition and accumulation of atmospheric particles [42]. Deposition, removal and accumulation processes are numerous and complex, [43] depending on the physical and chemical properties of the particles, the nature of the surface, the local meteorology and the pathways followed by rainwater after it hits the building surface [44]. As a result of these complex interactions, there can be substantial variations in the level of soiling observed on building surfaces.…”

Section: Resultsmentioning

confidence: 99%

Effect of Air Pollution on Archaeological Buildings in Cairo

Khallaf¹

2011

Monitoring, Control and Effects of Air Pollution

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Section: Resultsmentioning

confidence: 99%

Effect of Air Pollution on Archaeological Buildings in Cairo

Khallaf¹

2011

Monitoring, Control and Effects of Air Pollution

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“…Whilst previous pore characterization mostly relied on subjective 2D descriptions of 3D pore structures (Vazquez-Calvo et al, 2007) or by means of computerized reconstructed models (Latief et al, 2010), recently, more and more X-ray CT is being used combined with image analysis to allow complex 3D characterization. Already in the early days of synchrotron Xray micro-CT the technique was used to directly image the 3D pore structure of rocks at micrometers resolution.…”

Section: X-ray Micro-ct Used In Geosciencesmentioning

confidence: 99%

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

Cnudde

Boone

2013

Earth-Science Reviews

1,228

700

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Please cite this article as: Cnudde, V., Boone, M.N., "High-resolution X-ray computed tomography in geosciences: a review of the current technology and applications", Earth Science Reviews (2013Reviews ( ), doi: 10.1016Reviews ( /j.earscirev.2013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T AbstractHigh-resolution X-ray Computed Tomography (HRXCT) or micro-CT (µCT) is a frequently used non-destructive 3D imaging and analysis technique for the investigation of internal structures of a large variety of objects, including geomaterials. Although the possibilities of X-ray micro-CT are becoming better appreciated in earth science research, the demands on this technique are also approaching certain physical limitations. As such, there remains a lot of research to be done in order to solve all the technical problems that occur when higher demands are put on the technique. In this paper, a review of the principle, the advantages and limitations of X-ray CT itself are presented, together with an overview of some current applications of micro-CT in geosciences. One of the main advantages of this technique is the fact that it is a non-destructive characterization technique which allows 4D monitoring of internal structural changes at resolutions down to a few hundred nanometers. Limitations of this technique are the operator dependency for the 3D image analysis from the reconstructed data, the discretations effects and possible imaging artefacts. Driven by the technological and computational progress, the technique is continuously growing as an analysis tool in geosciences and is becoming one of the standard techniques, as is shown by the large and still increasing number of publications in this research area. It is foreseen that this number will continue to rise, and micro-CT will become an indispensable technique in the field of geosciences.

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“…Patina is an all-embracing term in the terminology of surface changes of materials due to natural ageing by chemical-physical reactions going on near, at and above the original surface of a stone. These includes interaction between the surface of the stone and the environment, biological activity, as well as ancient protective treatments [6]. These aging processes can manifest themselves as films and external deposits.…”

Section: Introductionmentioning

confidence: 99%

Brownish alterations on the marble statues in the church of Orsanmichele in Florence: what is their origin?

2015

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Introduction: The paper describes the complex investigations carried out to understand the sources of the brown chromatic changes that have occurred on ten marble statues dated back to the first half of the 15th century and now located in the Church of Orsanmichele in Florence, Italy. When the statues were removed from the outdoor niches for restoration in the 1980s, they appeared covered with a dark brown patina (called 'bronzatura') that dated to interventions occurred just after 1789. Archival documents confirmed that they had been carried out to make the marble statues look like bronzes. Because of the removal of the dark patina carried out by the Opificio delle Pietre Dure in the 1990s, the marble almost regained its distinguishing clear tonality even if darker areas remained. After the statues were placed indoors at the end of restoration, brownish discolorations started to appear on their surfaces. Results: Research began by using various non-invasive analyses (photographs under ultraviolet illumination, fluorescence lifetime imaging, x-ray fluorescence). The results of UV fluorescence tests and FLIM showed that the fluorescence emission's distribution map does not have distinctive and homogeneous characteristics in relation to the areas with the discoloration. Therefore, it is not a superficial film, but rather a phenomenon affecting the marble structure. Then we performed invasive analyses on samples from some statues. The results of optical microscopy, ATR-FTIR and Raman spectroscopy on cross sections, pyrolysis-gas chromatography/mass spectrometry on powdered samples from the surfaces and/or the bulk of the marble allowed the identification of the various substances involved in the chromatic alteration. Most important was the detection of weddellite and gypsum on the surface and within the marble. This finding, combined with the presence of lipids inside the stone, suggests that mineralization of treatments have occurred, causing discolorations.

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Characterization of patinas by means of microscopic techniques

Cited by 42 publications

References 9 publications

Effect of Air Pollution on Archaeological Buildings in Cairo

Effect of Air Pollution on Archaeological Buildings in Cairo

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

Brownish alterations on the marble statues in the church of Orsanmichele in Florence: what is their origin?

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