1,720,991 research outputs found
Technological and provenance study of renaissance earthenware fron Aosta (Italy)
No full textSome archaeological investigations, promoted by Regione Autonoma Valle d’Aosta, Assesorato alla Cultura and Servizio Beni Archeologici, have been carried out in 2005, just in front of the Aosta Cathedral. The excavation revealed the workshop and the kiln where architectural earthenware, used for the Cathedral façade decoration, were produced and fired.
The construction of the new Cathedral façade was started in the second half of XV century and finished in 1526. The polychrome earthenware Renaissance Apostle statues are located in the arch entrance which is decorated with flowers tiles.
Flower tile sherds, clay mixtures, raw clay bricks and firing scraps have been found in the excavation. These findings suggest that only the tiles for the Cathedral decoration were fired in the kiln, as scraps from the sculptures weren’t excavated and the small size of the kiln suggests that the statues were made in another workshop. Evidences from the clay materials suggest two possible provenances: a local deposit, probably known by Romans, and/or a deposit in the Eporediese (Ivrea region).
In this work the manufacture process and the firing conditions are reconstructed through the petrological and mineralogical study of the archaeological findings. Thin sections of tile sherds have been studied to determine their textures and components. Moreover firing tests have been run on mixtures obtained using the original clay materials from the excavation in order to locate the clay provenance area and to compare them with the actual tiles and to reconstruct the technological features of the craftmen.
The observation under polarizing light optical microscope allow to correlate the clay mixtures with the scraps. The yellowish clay found in the excavation has been fired at 850°C and compared with three tiles fragments found in the same spot. The fired yellow clay mixture is texturally characterised by alternating bands consisting of layers with a high temper percentage content and layers with high percentage of matrix. The same texture is observed in the tile sherds from the excavation, supporting that tiles were produced using these raw materials.
Future development of this work is the examination of the clays, tiles, scarps and mixture firing tests by Scanning Electron Microscopy (SEM) and X-Ray Fluorescence
A combined use of FORS, XRF and Raman spectroscopy in the study of mural paintings in the Aosta Valley (Italy)
No full textMural paintings which decorate the external
façade and the internal apsidal wall of a chapel dedicated
to St. Maxime and located at Challand St. Victor in the
Aosta Valley (Italy) have been analysed with a combined
approach involving high-resolution fibre-optic reflectance
spectroscopy (FORS), X-ray fluorescence (XRF) spectrometry
and Raman spectroscopy. The paintings are attributed
to Giacomino from Ivrea, a painter active around the midfifteenth
century. In order to characterise the palette used by
the painter and to yield information useful to restorers, the
cited techniques were used either in situ with portable
instruments and in laboratory, working on micro samples
withdrawn from paintings. The global analytical approach,
though not entirely non-invasive, can indeed be considered
non-destructive as multiple analyses, including SEM-EDX,
could be carried out on the micro samples, exploiting the
features of each technique. On the basis of the information
obtained, the palette was found to be composed of typical
fresco pigments such as calcite, azurite, malachite, vermilion,
red and yellow ochres. A particular situation was noted
for black pigments since the presence of graphite, rather
than wood or lamp carbon, was found, possibly related to
the presence of graphite deposits in the Aosta Valley.
Furthermore, the presence of smalt superimposed to azurite
in areas showing evidence of repainting was detected,
suggesting that paintings were subjected to retouching at a
relatively early stage after the original execution. Finally,
the presence of tin foils, used to decorate haloes of
Evangelists, was ascertained
Computer-aided Monitoring of Buildings of Historical Importance based on Color
No full textThis paper presents an application of image processing tools in the field of cultural heritage. The proposed strategy allows us to improve and make semi-automatic the study of chemical decay causing visible changes in color of some regions. So, it is possible to semi-automatically detect the regions corrupted by a specific kind of decay from a color image showing the degraded surface of a building of historical importance. The decay will be indicated by the expert via mouse clicks on the image under study. The second phase of the proposed framework consists of selecting a subset of the regions achieved in the first one. The number of regions in the subset is selected by the expert. The remaining operations are automatically performed via an optimization approach. Both phases try to embed experts' knowledge. The final result will be a map of points on the surface from which extracting a bit of material to study in depth via chemical laboratory tests. We outline the potentialities of the proposed non-invasive technique, oriented to avoid some drawbacks of the classical “naked-eye” approach. Even though the proposed framework is guided by the expert, it is semi-automatic and able to reduce typical human limits such as subjective and emotive state, visual system performances and so on. Experimental results, achieved on some images of the Roman Theatre in Aosta, will be presented and discussed
Investigation of Roman Terra Sigillata by atomic absorption and emission spectroscopy and multivariate analysis of data
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Monitoraggio della mappa di rischio di monumenti a larga scala mediante elaborazione di immagini
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Identificazione dei coloranti naturali con metodi non invasivi
No full textIl lavoro presenta i risultati preliminari ottenuti da un’indagine sistematica condotta con spettroscopia in riflettanza con fibre ottiche (FORS) nel campo spettrale visibile su un elevato numero di campioni di riferimento in lana e seta tinti con diverse materie prime coloranti naturali (anche in miscela) impiegando vari mordenti e diverse procedure di tintura.
L’analisi degli spettri FORS ottenuti ha consentito di valutare la presenza di caratteristiche spettrali discriminanti per alcune tra le diverse materie prime coloranti considerate (blu e rosse in particolare) e di valutarne le modificazioni associate ai differenti substrati e mordenti, oltre che evidenziarne gli effetti dovuti alla saturazione della tinta
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