388 research outputs found
FUXYA2020: A Low-Cost Homemade Portable EDXRF Spectrometer for Cultural Heritage Applications
No full textThe project FUXYA2020 was intended to design and prototype a low-cost basic energy dispersive X-ray fluorescence spectrometer for all those cases where there is not enough financial support to buy a commercial device. Indeed, home-made instruments are ideal when funds are low but constant over the years, as this approach allows the costs to be spread over a longer period of time. The FUXYA2020 was intended mostly for cultural heritage (CH) applications: we optimized the geometry to meet the requirements for both low Z matrix objects, such as glasses and ceramics, and medium-high Z materials, such as metals; besides, we designed a positioning system through Arduino components to obtain good results and repeatability for samples with a complex geometry. The FUXYA2020’s performance was tested both for qualitative and quantitative analyses, the former on pigment layers, and the latter on gold-based certified alloys, exploiting Axil-QXAS software for data elaboration. The classification of ancient ceramics based on multivariate analysis obtained through R environment was also carried out. The qualitative data on pigments have also been compared with the same data obtained by a commercial XRF spectrometer, demonstrating how our very simple and inexpensive prototype can be of great help for a rapid and reliable characterization of cultural heritage materials whenever commercial devices are unaffordable
UV-IR image enhancement for mapping restorations applied on an Egyptian coffin of the XXI Dynasty
No full textThe use of non-invasive analytical techniques on cultural heritage objects usually faces the insurmountable limit of dealing with artworks subjected to more restorations. For painted surfaces, imaging techniques, such as infrared photography (NIR) and ultraviolet-induced visible fluorescence (UVIVF), allow to distinguish areas with different kind and period of interventions. This paper presents the application of such techniques on two wooden coffins of the 21st Dynasty with a complex restoration history, the analytical inspections deal with the issues occurring in the reconstruction of a fluorescence map that is influenced by on both the use of non-original pigments and the presence of protective varnishes. In uncontrolled laboratory conditions, the possibility to associate quantitatively and univocally the luminance recorded by the camera with a certain level of fluorescence can be very difficult. An algorithm has been developed to obtain a map with an evident relationship between fluorescence and diagnostic information. First, the pixels of the fluorescent areas presenting different reflectance in the visible image have been used to equalize the visible image. Then, the ratio of the UVIVF image to the equalized image has been calculated, highlighting the low and non-fluorescent areas. After the thresholding and the segmentation of the UVIVF image, the masks obtained have been overlaid on the NIR images to merge and to map the areas with supposed similar restoration materials. The results illustrated in this work are followed by a punctual spectroscopic campaign, where the information on the imaging analysis is linked to and completed by the study of the chemical compounds in the coffins
More than XRF Mapping: STEAM (Statistically Tailored Elemental Angle Mapper) a Pioneering Analysis Protocol for Pigment Studies
No full textAmong the possible variants of X-Ray Fluorescence (XRF), applications exploiting scanning Macro-XRF (MA-XRF) are lately widespread as they allow the visualization of the element distribution maintaining a non-destructive approach. The surface is scanned with a focused or collimated X-ray beam of millimeters or less: analyzing the emitted fluorescence radiation, also elements present below the surface contribute to the elemental distribution image obtained, due to the penetrative nature of X-rays. The importance of this method in the investigation of historical paintings is so obvious—as the elemental distribution obtained can reveal hidden sub-surface layers, including changes made by the artist, or restorations, without any damage to the object—that recently specific international conferences have been held. The present paper summarizes the advantages and limitations of using MA-XRF considering it as an imaging technique, in synergy with other hyperspectral methods, or combining it with spot investigations. The most recent applications in the cultural Heritage field are taken into account, demonstrating how obtained 2D-XRF maps can be of great help in the diagnostic applied on Cultural Heritage materials. Moreover, a pioneering analysis protocol based on the Spectral Angle Mapper (SAM) algorithm is presented, unifying the MA-XRF standard approach with punctual XRF, exploiting information from the mapped area as a database to extend the comprehension to data outside the scanned region, and working independently from the acquisition set-up. Experimental application on some reference pigment layers and a painting by Giotto are presented as validation of the proposed method. View Full-Tex
Flash Thermography Mapping of Degradation Patterns in Archaeological Glass
No full textThe process of degradation in artefacts subjected to centuries of burial can be of great relevance above all in archaeological glass. Infrared thermography is a non-destructive method allowing to map the defects of the glass substrate, both produced during its manufacturing (e.g., bubbles and inclusions) and due to ageing. This research is focused on the use of different flash thermography methods for the mapping of superficial flakes on Roman glasses dating back to the I and II century A.D. The effectiveness of active thermography methods is evaluated to map degraded portions of archaeological glass considering their semitransparency and specific optical absorption
The role of IRT in the archaeometric study of ancient glass through XRF and FORS
No full textThe process of degradation of archaeological glass subjected to centuries of burial can be of great relevance: typical consequence of degradation in the original vitreous material is rainbow-like iridescence due to chemical alteration of surface layers, salts formation and ion migration. The research presented in this paper is focused on the study of a collection of Roman glass (I - II century A.D.) held by the Museo Civico Etnografico Archeologico Fanchini of Oleggio, Italy. Chemical characterization (namely flux, chromophores and opacifiers determination) has been performed by a combination of X-Ray Fluorescence (XRF) and Fibre Optics Reflectance Spectroscopy (FORS) in the UV–Vis-NIR region. Conservation conditions have been studied and degraded areas have been mapped through Infrared thermography (IRT). IRT is a non-invasive method typically used to measure the apparent temperature of objects and represent it as pseudo-colour images. In the present work, we demonstrate the feasibility of IRT for identifying and mapping glass substrate defects due to ageing of glass, assuming that they may be considered as thermal anomalies. Thermogram sequences have been processed by high order statistical analysis, which is particularly suitable since it is based on automated processes where the output is a single representative image. The use of a thermal camera allows furthermore to perform remote analysis in areas hardly reachable in a fast and effective way
Jacopo Sadoleto: De Laocoontis statua (1506) (FONTES 5)
No full textWhen the statue of Laocoon and his two sons in the clutch of the serpents was discovered near the Colosseum at the beginning of 1506 the excitement was great, and young Jacopo Sadoleto, later a cardinal, then a devoted humanist, composed a poem on this masterpiece based on classical verse. Sadoleto’s text is not without echoes of Vergil’s famous lines about Laocoon and his fate, and with an astonishingly independent judgment on the quality of the subject. This text has been printed in various modern publications on Sadoleto, respect to the Laocoon, but only the edition by the present author, produced in 1992, offered a critical text based on a comparison of all extant printed versions from the 16th and 17th centuries, along with a brief linguistic commentary. Since no other attempt to recover the original text and no more recent commentary have hitherto appeared, the text and commentary of the 1992 publication are here reprinted in a partly abridged, partly enlarged form in order to provide the interested scholar with a reliable text and some linguistic basics as materials for further interpretation
Plausibility or truth. Archival notes and reflections on the canvas of the ‘Militant and triumphant Church’ ascribed to Jacopo Zucchi
No full textWhile retracing the traditional history of the painting, which was fi rst ascribed to Federico Zuccari and later to
Jacopo Zucchi, the author hereby presents the long and painstaking research that has gradually confi rmed this
second hypothesis. The reader will, therefore, fi nd a synthesis of the history of this painting, which was surely
enough fi rst hosted in St Peter's Basilica, then moved to the Church of St Catherine of Alexandria and fi nally to
the Vatican Sacristy. Based on a number of inconsistencies which emerged during archival research, doubts still persist with regard to
the historicity of this historical-artistic tradition. Despite the fact that scholars are fi rmly inclined to ascribe the
painting to Zucchi, some unpublished documents tend to undermine this assumption, while still implying that the
painting might be by an artist of the Zuccari famil
Application of statistical analyses for Lapis Lazuli stone provenance determination by XRL and XRF
No full textLapis Lazuli use stretches back more than 6,500 years; ancient civilizations of Mesopotamia, Egypt, China, Greece, and Rome treasured and prized it. Afghanistan has been the oldest source for this stone, while Chile, Canada, Russia and a few other countries have been reported as sources for raw material in more recent times; the rarity of historical mines surely represents a positive aspect for the provenance clue of artefacts. Lapis lazuli is a rock consisting mainly of lazurite, to which it owes the blue colour, calcite and pyrite. Other constituents may be present, related to the different mines. In the present work, we apply the principles of Radio-luminescence (RL) exploiting as radiation source the X-ray tube of a portable commercial X-Ray Fluorescence spectrometer; in this way, X-Ray Fluorescence spectra (XRF) can be simultaneously acquired to have a larger set of data. To highlight the instrumental experimental differences, we refer to the portable set up as X-Ray Luminescence (XRL), as suggested by recent literature. We thus looked for the possibility of applying a wieldy, low cost and non-destructive method that could fit also to precious objects, based on the join use of XRF and XRL. We performed analyses on raw Lapis Lazuli stones from five different provenances, both historical and modern, and on four sets of unknown origin carved polished stones, to test our methods on real artefacts. We focalised on a limited number of samples to concentrate on the statistical treatment of spectra obtained, so to get a synergic response of the two applied techniques. We were able to obtain a clear distinction for the different classified provenances and could speculate those of unknown samples
Raw Mapping data
No full textRaw data acquired with a Bruker IRIS hyperspectral scanner.
Spectral reflectance data between 400 and 2500 nm.
X-ray fluorescence data
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