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The historical pigments, contrary to modern ones, are not constituted by particles having all the same size and this influences the colour of the paint layers. The hiding power and colouring power of a pigment depends, in fact, on its particle size. The aim of this study was to evaluate the influence of particle size on optical characterization of paintings in terms of reflection of light and related colour specification. Starting from the qualitative observation, we have attempted to quantify the pigments colour variations induced by grinding and then attributable to granularity. Powdered pigments of principal colours have been selected in specific particle size range by mechanical sieving. The measurements were performed both on pigment pellets and on paintings realized with binder casein. All samples were characterized by an optical and colorimetric point of view through spectrophotometric analysis and for the surface morphological observation through scanning electron microscopy.

An on-line database was compiled for the Raman and fluorescence spectra, obtained using three different excitation wavelengths (531.5, 632.8 and 780 nm), of 99 pigments analysed dry and already applied with four painting techniques (egg tempera, casein tempera, oil and fresco). The database makes it possible to determine easily the most suitable excitation wavelength for the identification of pigments already applied with these painting techniques.

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a b s t r a c tAn experimental intercomparison was performed with brick samples from an early medieval building in the west of France, the St-Philbert-de-Grandlieu abbey. A potentially complex set of microdosimetric problems emerged from characterisation measurements, providing a robust test of the routine procedures used by each laboratory. The dating results obtained using quartz coarse grains and fine grain samples span over a large period of time, exhibiting overdispersion, and where systematic deviations appear between quartz and fine grain chronologies. Factors causing such scatter are analysed in detail, including internal radioactivity of quartz grains, millimetre-scale heterogeneity in the fabric, and the observation and modelling of fading behaviour of fine grain minerals.

Abstract:In the last years the mortar dating through Optically Stimulated Luminescence (OSL) techniques has become a viable support for chronological estimations (date of construction or restoration episodes) of historical buildings. However, the dating of mortar has still open issues mainly regarding the assessment of the bleaching degree of quartz, the analysis of the OSL processes for this type of samples and the need to do appropriate tests for the most correct evaluation of the equivalent dose. This paper discusses the results obtained by OSL dating (blue diode stimulation) on the polymineral fine grain phase, enriched in quartz, extracted from lime mortar samples collected from different sites. Thermal transfer effects, through the behaviour of Equivalent Dose (ED) and recovery tests, degree and time of bleaching were studied. For each mortar sample the adjacent brick was collected; in some cases, sampling of the bricks bracketing a mortar layer was a possibility, thus obtaining a direct comparison with the standard thermoluminescence (TL) dating on the bricks. The results obtained show, for this set of samples, the possibility of dating the mortars through the use of the fine grain fraction provided of a suitable chemical-physical preparation procedure and the verification of the bleaching conditions.

Abstract. Analysis of tsunami deposits from the Pantano Morghella area provided geological evidence for two inundations occurred along the south-eastern Ionian coast of Sicily. Pantano Morghella is a large pond characterised by a finegrained sedimentation indicating a low-energy depositional environment. Two anomalous yellow sandy layers found at different depths indicate the occurrence of high-energy marine inundations. We studied sedimentological and paleontological features of the anomalous deposits as well as their spatial distribution observing the following properties: different facies with respect to the local stratigraphic sequence; erosive bases, rip-up clasts and broken elements testifying violent deposition mechanisms; macro and micro fauna of marine environment; relatively constant thickness throughout most of the depositional zone with thinning at the distal end; large sand sheets that extend inland. These observations, jointly with their infrequency in the sedimentary record and the age indicating a fast deposition, provided strong evidence for tsunami inundations. Correlations between anomalous layers and historical tsunamis are supported by radiocarbon and OSL dating results. The younger deposit is likely due to the 1908 near-source tsunami, whereas the flooding of the oldest event is most likely associated with a far and large source, the Crete 365 AD earthquake.

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